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CON 251 Lab Notebook

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CON 251 Lab #1Measurements Lab Activity

IntroductionThis lab activity is to familiarize students with a variety

of measurement methods and measuring instruments that are used for testing. Students will use the following measuring devices for this lab activity:

Tape MeasureRulerDial caliperDigital caliperMicrometerThread pitch gageProtractorTriple beam scalePin gages

Procedure:

This lab activity has ten different stations that require measurements and or calculations that need to be collected. Start at any station and complete the activity then move to the next open station. When measurements have been taken at all stations each group will need to complete the calculations or summaries away from the stations so others can gain access. When the lab is completed, keep the report and add it to your workbook.

Sample #1Measure the length of the 2X4 to the nearest 1/16”

Length

Sample #2

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Using a dial caliper, measure the diameter and length of the round piece of aluminum to the nearest .001”.

Diameter

Length

Cross Sectional area

Volume

Sample #3Using a digital caliper, measure the diameter, inside (ID) and outside (OD) and the length of the aluminum tube to the nearest .001”.

Diameter (OD)

Diameter (ID)

Length

Cross Sectional Area of the aluminum only

Volume

Sample #4Using a Digital Caliper, what is the length and width of the rectangular pocket (measure to the nearest .001”) ?

Length Width

Sample #5Using a steel rule, what is the length and width of this blue aluminum plate to the nearest 1/16” ?

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Length

Width

Sample #6Using a digital caliper, what is the depth and width of the blue groove in this part to the nearest .001”?

Depth

Width

Sample #7Using a steel rule and thread pitch gage, what is the nominal diameter and the thread pitch of this bolt? (nominal) diameters of fasteners are measured in 1/16” fractions.)

Bolt Diameter

Threads per inch (thread pitch gage)

Sample #8Using a micrometer, measure the width and thickness of the square tool to the nearest .001”.

Width

Thickness

Sample #9Using pin gages, determine the diameter of holes A, B, & C.

Diameter A

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Diameter B

Diameter C

Sample #10Using a Digital caliper, measure the width and thickness of this block. Also measure the diameter of the round hole and the length of the slot above the hole to the nearest .001”.

Width

Thickness

Diameter of the hole

Length of the slot

Sample #11Using the adjustable protractor, measure all three angles to the nearest degree.

Angle A

Angle B

Angle C

Sample #12 Using the test procedure provided on the last following page to calculate the Relative Density of samples A, B, and C.

A

B

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C

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Relative DensityASTM D-792

Density= A - B (A-B) - (C-D)

Where:A = mass of the specimen +Wire in Air

B= mass of wire in air (.58 g)

C= mass of wire & specimen immersed in water

D= mass of wire with end immersed in water (.54 g)

Sample A mass in air (A) Sample A mass in water (C)

Sample A Relative Density

Sample B mass in air (A) Sample B mass in water (C)

Sample B Relative Density

Sample C mass in air (A) Sample C mass in water (C)

Sample C Relative Density

CON 251 Lab #2Metallic Tensile Testing Lab Activity

Introduction:

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The tensile test is a common test performed on metals, wood, plastics, and most other materials. Tensile loads are those that tend to pull the specimen apart, putting the specimen in tension. They can be performed on any specimen of known cross-sectional area and gage length to which a uniform tensile load can be applied.Tensile tests are used to determine the mechanical behavior of materials under static, axial tensile, or stretch loading. Data and calculations for these tests include tensile stress, tensile strength, elastic limit, percent elongation, modulus of elasticity, proportional limit, percent reduction in area, yield point, yield strength, and similar properties.ASTM standards for common tensile tests may be found in sections E8 (metals), D638 (plastics), D2343 (fibers), D897 (adhesives), D987 (paper), and D412 (rubber).

Tensile Testing – Procedure:

Tensile tests are used to determine the tensile properties of a material, including the tensile strength.

In order to conduct a tensile test, the proper specimen must be obtained. This specimen should conform to ASTM standards for size and features. Prior to the test, the cross-sectional area may be calculated and a pre-determined gage length marked on the specimen (usually 2”). This gage length is used to determine the amount of elongation that has taken place on the test specimen. The specimen is then loaded into a machine set up for tensile loads and placed in the proper grippers. Once loaded, the machine can then be used to apply a steady, continuous tensile load.Data is collected at pre-determined points or increments during the test. Depending on the material and specimen being tested, data points may be more or less frequent. Data include the applied load and change in gage length. The load is generally read from the machine panel in pounds or kilograms. The change in gage length is determined using an extensometer. An extensometer is firmly fixed to the

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machine or specimen and relates the amount of deformation or deflection over the gage length during a test.While paying close attention to the readings, data points are collected until the material starts to yield significantly. This can be seen when deformation continues without having to increase the applied load. Once this begins, the extensometer is removed and loading continued until failure. Ultimate tensile strength and rupture strength can be calculated from this latter loading.Once data have been collected, the tensile stress developed and the resultant strain can be calculated. Stress is calculated based on the applied load and cross-sectional area. Strain is the change in length divided by the original length.Principal properties determined through tensile testing include yield strength, tensile strength, ductility (based on the percent elongation and percent reduction in area), modulus of elasticity, and visual characteristics of the fracture. For brittle materials, which do not show a marked yield or ductility, data is collected for tensile strength and type and condition of fracture.Expected ResultsThe results of tensile testing can be used to plot a stress-strain curve that illustrates the tensile properties of the material. Stress (in pounds per square inch or Pascal’s) is plotted on the vertical axis while strain (inches per inch, millimeters per millimeter, or unit less) is plotted along the horizontal.As the load is applied, the curve is proportional and this period of linearity is termed the elastic region. Once the curve deviates from a straight line and begins to yield, the material has reached the proportional limit. Once the material has yielded, it exhibits plastic behavior or plasticity. Brittle materials do not exhibit much yield and are, therefore, less curved than ductile materials. Ductile material curves have marked areas of yield and curvature illustrates the degree of ductility. At the top of the curve is the ultimate tensile strength of the material. Once the curve has peaked, stress continues to decline while strain continues to increase. This condition continues until failure.

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As with any testing situation, please observe caution and wear proper safety equipment.

Text References:

Chapter 14 – Tensile Testing

Appendix 2C pg. 479

Also see pages 474 & 475 for Stress Strain curves

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CON 251 Lab #2Tensile Testing Data

Sample # 1 *Thickness *Width *Peak Load lbs.**Load at Yield lbs.*Peak Load at Rupture lbs.

* Measured or observed values** Interpreted from Plot

(Ultimate Tensile strength ) σ = Load at Peak = psi

Cross Sectional Area

(Strain at Peak load)

Strain* =

Strain* = (final length – starting length)/ starting length

*At peak load

(Modulus of Elasticity)

Modulus of Elasticity = Stress/ Strain


Percent Elongation =

Per Cent Elongation = final length*- starting length X 100

Starting length* final length after break

Sample # 2 *Thickness *Width *Peak Load lbs.**Load at Yield lbs.*Peak Load at Rupture lbs.

* Measured or observed values** Interpreted from Plot

(Ultimate Tensile strength ) σ = Load at Peak = psi

Cross Sectional Area

(Strain at Peak load)

Strain* =

Strain* = (final length – starting length)/ starting length

*At peak load

Modulus of Elasticity


Modulus of Elasticity = Stress/ Strain

Percent Elongation =

Per Cent Elongation = final length*- starting length X 100

Starting length

*final length after break

Problem:We want to use #3 rebar to pre-stress a concrete beam.

How much load must be applied to the rebar to stress it to 80 % of its ultimate tensile strength?

Procedure:1. Reduce a middle section of the rebar sample

on the engine lathe. (Turn until cleaned up)

2. Measure the smallest diameter of the turned area.

3. Using the Vega Tester, apply a load until the sample ruptures.

4. Calculate the ultimate Tensile Strength

5. Use a value of 80% of the calculated ultimate tensile strength to determine pre-stress value.


6. Use a value of 80% of peak load to approximate pre-stress load.

Turned Diameter Cross Sectional Area

Load at Rupture lbs.

Ultimate Tensile Strength psi.( Ultimate Tensile Stress = Load at Rupture / Area )

Pre-stress Load lbs.(80% of load at Rupture)

Pre-stress value psi. (80% of Ultimate Tensile Stress)

CON 251 Lab #3

Hardness Testing Heat and Treatment of Steel

Introduction (Chapter reference Chapter’s 4 & 19)

One of the most desirable characteristics of steels is the ability to easily change the hardness and strength the material. This process of changing the hardness is referred to as heat treatment. Steels are classified as carbon steels, alloy steels or special steels. This activity will focus only on carbon steels. The classifications of steels was established by the Society of Automotive Engineers (SAE) and later adopted by the American Iron and Steel Institute (AISI) and is now referred to as the SAE-AISI system of steel classification.

Carbon steel is an alloy of iron and carbon, without significant amounts of other elements. Therefore the carbon content plays the most important role in determining the properties of carbon steel. About 85% of all steel is carbon steel. About 130 different grades of carbon steel are


produced today to meet the growing needs of modern technology. Carbon steels are classified as low carbon, medium carbon or high carbon steels. The amount of carbon content determines which classification the steel is in. Low carbon steels contain between 0.08% and 0.35% carbon. In terms of tonnage produced, low carbon steels constitute the larges volumes with the extensive use as structural members in buildings and bridges. These steels can be easily welded, formed and forged, but have poor machining properties. Due to their low carbon content cannot be hardened through conventional heat treatment. Medium carbon steels are those with carbon content between 0.35% and 0.50%. Because of relatively high carbon content, these steels can be hardened by water quench and tempered. Medium carbon steels are considered the most versatile of all carbon steels because they can be hardened, easily welded and machined. High carbon steels are those with carbon content over 0.55%. The outstanding characteristics of these steels are that they can be heat treated more readily than any other carbon steels. However, because of the high carbon content these steels are relatively difficult to machine, form and weld. They are used for springs, hand tools, cutting tools and agricultural implements such as plow shears and cultivating shoes. OBJECTIVES: To introduce those solid-state transformations of material structures, known as “heat-treatments”. More specifically, define “heat treating” as the controlled heating and cooling of metal alloys in the solid-state. The process starts by heating the steel above its critical temperature or austenitic temperature range. (Between 1333F and 1666F), which transforms the iron into austenite . The slow cooling of steel from its critical temperature over several hours or days is called “Annealing”. Annealing


leaves the steel in its softest possible condition with the least amount of internal stress and maximum malleability. “Normalizing” involves heating the metal into its critical temperature then letting it cool in still air at room temperature. Normalizing forms even grain size that makes them easier to machine. “Quenching” is the process used to harden steel through out (through hardening) and is performed by heating the metal into its critical temperature then rapidly cool it back to room temperature. This rapid cooling causes the austenite to form into “Martensite” which is very hard and brittle. This will form the hardest and highest strength steel but is extremely brittle and has a high amount of internal stress. Depending on the carbon and alloying content, different quenching media are used. The most common media are, water, brine (salt water), oil and air. Water or brine provides the most rapid quenching. Oil is slower than water with air quenching being the slowest. “Tempering” is also referred to as drawing, is a process by which a hardened part is reheated to 400F to 800F and quenched in water. This process will relieve stress, reduce hardness and increase toughness of the processed part. “Case hardening” is also referred to as surface hardening and is used on such parts as gear teeth, axles and other parts and tools. These case hardened parts represent a compromise between the hard, wear resistant brittleness of high carbon steels and the softer, more ductile, less wear resistant low carbon steels.


The purpose of this lab activity is to familiarize the student with the terminology and methods used for steel classification and heat treatment. The lab activity will involve hardening, annealing, case hardening, tempering and Rockwell hardness testing.

Procedure: You must wear safety glasses for this lab1. Each group will get one sample each of O-1 tool

steel 5/16” X3” round and 5/16”X3” round 1018 Cold Rolled Steel (CRS).

2. Using the Rockwell hardness tester, measure the hardness of each sample. (take two readings for accuracy and record)

3. Using the oxy-acetylene torch heat approximately 1” of each sample until it is orange, then quench quickly in water. (Use pliers to hold samples)

4. Bead blast the ends of the samples that were hardened. This will remove oxides and scale from the samples.

5. Repeat step 2. Making measurements in the middle of the hardened section. (take two readings for accuracy and record)


CON 251 Lab#3Heat Treatment and Hardness Testing Data

5/16” Round O-1 untreated RC

5/16” Round O-1 hardened RC

5/16” Round O-1 tempered RC

5/16” Round *CRS untreated RC

5/16” Round *CRS hardened RC

* Note CRS stands for Cold Rolled Steel

Briefly explain what occurred when a sample of O-1 was hardened and then held in a vise and hit with a hammer.

Briefly explain the advantages and disadvantages of through hardening and Case hardening.

CON 251 Lab #4Masonry Screw Anchors Testing Lab Activity

Introduction:


Fasteners are a essential component used in the construction industry for connecting a variety of hardware or accessories to rigid structures such as walls, stone or brick. There are numerous fastening devices and systems that are used for numerous different applications. With so many choices, it is often times difficult to determine what fastener is best suited for a particular application. In many instances specifications and or callouts will specify precisely what fastener must be used. Most of the time a sub-contractor will use what is most familiar to him or her or what can be purchased at the best price.

The application that we will examine is that of the holding strength of a variety of different screw anchors. Two types of loading can occur with a screw anchor mounted on a vertical wall. The first is downward shear caused by the loading similar to a shelf bracket screwed to a wall. As loads are placed on the shelf, the downward force creates a downward shear between the bracket holding the shelf and the wall. The second is the pullout force applied as a result of the cantilever of the bracket pulling away from the wall. While both forces are at issue, most concern is usually with the forces applied from the cantilever more than the downward shear. This is because the shear forces are the greatest closest to wall and will increase the force on the cantilever as the load moves further from the wall. The tests will be conducted using #10 or 3/16” diameter fasteners. Typically wood screws, sheet metal screws and machine screws are used for these applications, depending on the type of anchors used.

Procedure:

Each group will test two different screw anchors. Holes will be drill according to the diameter specified for that type of anchor. Location of the holes is centered on the edge of the brick and 2-3/4” in from either end. Both edges of the brick will need to be drilled. One edge of the brick will be used to test the shear strength of the fastener and anchor. The other edge will be used to test the pullout force


necessary to dislodge the fastener and anchor from the brick. This test will emulate a cantilever load being applied to the fastener and anchor. The pullout force test will be performed on the AST digital tester located in the metrology lab. The shear tests will be performed on the Testmark Compression Testing machine. The instructor will demonstrate both testing machines and procedures.

The anchors that can be tested are as follows:

1. Tapcon masonry screws (drill 5/32” hole 1” deep)

2. Flanged Conical Plastic Screw Anchor (drill ¼” hole 1-1/14” deep)

3. Flanged and Grooved Conical Screw Anchor (drill ¼” hole 1-1/14” deep)


4. Caulking Bolt for #10 Machine Screw (drill 3/8” hole 1” deep)

Insert the anchors into drilled holes and tap with a hammer to insure that the anchor is fully seated. Only put screw and anchors in one edge of the brick at a time. On the edge that will be used for the pull out test, leave about 5/8” of the screw sticking out of the brick. When you perform the shear test, screw the 3/8” steel plate to the brick but do not over tighten the screw. Shear each screw separately moving the plate to the opposite end of the brick to perform the second shear test.


CON 251 Lab #4Masonry Screw Anchors Testing Lab Activity

Shear Test Type of Anchor Force Applied To Failure

Anchor # 1 lbs.

Anchor # 2 lbs.

Pullout Test Type of Anchor Force AppliedTo Failure

Anchor # 1 lbs.

Anchor # 2 lbs.

Based on your test results, briefly explain which fastener and anchor proved to withstand the greatest shear and which fastener and anchor proved to withstand the greatest pullout force? Which combination was the best buy?


CON 251 Lab #5Holding Strength of Framing Nails

Introduction:

One of the most widely used fasteners in the construction industry is the ordinary nail. Below is a brief history of the nail that is quite interesting.

A Two-Bit History of Nails by Paul Fourshee Copyright © 1992

The lowly nail’s history goes back several thousand years. While the nail has almost always been produced for fastening and joining, historically some other fairly imaginative applications have been made of this versatile product, such as mayhem and punishment. Bronze nails, found in Egypt, have been dated 3400 BC. The Bible give us numerous references to nails, the most well known being the crucifixion of Christ. Of course we should not forget that model wife in Judges who in 1296 BC drove a nail into the temple of her husband while he was asleep, “so he died.” (Thelma and Louise where is your imagination?) Exactly what do we mean when we refer to nail sizes by “penny?” You’re in good company if you have no idea. With 2,200 varieties of nails being manufactured today and everyone using them from the hobbyist to the professional builder, one would think, if it is such a good idea, that somebody would know what the term “penny” means and who started it. At long last an answer to the question you never asked. The term “penny”, as it refers to nails, is thought to have originated in medieval England to describe the price of 100 nails. (e.g. 100 3-1/2” nails would cost 16 pence, while 100 2-1/2” nails could be bought for 6 pence.) This system of classifying nails by size according to price was in place by 1477 AD. The letter “d”, which means penny, stands for the Latin name given to Roman Coins, Denarius.


The size of the nail is determined by measuring its length. Nails start at 2d, which is 1” in length, and range up to 60d which is 6” in length. From 2d to 16d the penny length increases by quarter inches. Above 16d, the size increases by half inches. Nails longer than 60d or shorter than 2d are described in inches or fractions thereof. Just prior to the American Revolution, England was the largest manufacturer of nails in the world. Nails were virtually impossible to obtain in the American Colonies so it was quite common for families to have a small nail manufacturing setup in their homes by the fireplace. During bad weather and at night, entire families made nails not only for their own use but also for barter. This was not a practice restricted to the lower classes, Thomas Jefferson was quite proud of his hand made nails. In a letter he wrote, “In our private pursuits it is a great advantage that every honest employment is deemed honorable. I am myself a nail maker.” From the president to the pioneer, nail making was an important facet of life. Jefferson was among the first to purchase the newly invented nail-cutting machine in 1796 and produce nails for sale. Such value was placed on nails that it was common practice, when moving, to burn one’s home in order to retrieve them. The invention of the nail cutting machine rapidly put the United States in front in the manufacturing of nails and has lead the world ever since. In the 1850’s several manufactures were established in New York which made wire nails. These machines were most likely imported from France. The earliest wire nails were not made for construction but for the manufacture of pocket book frames and cigar boxes. It was not until after the American War Between the States that wire nails began to gain acceptance in construction. Even through the 1890’s many builders preferred using cut nails because of their holding power. It was well into the twentieth century before wire nails became the dominate type and only then because they were so much cheaper.


It is because of the tremendous holding power and hardness that cut nails are still used today for specific functions such as flooring nails, boat nails and masonry nails. The Tremont Nail Company of Wareham, Massachusetts was established in 1819 and has manufactured cut nails continuously under several owners and names ever since. This company, now owned by Maze Nails, still makes 20 different types of cut nails with 100 year old machines. Their nails are still packaged in 100 # wooden kegs. Did you know that the holding power of common nails drops by half within two days after being driven? After about a month the holding power will increase slightly as the wood fibers straighten out and grip the nail. Cement coated nails hold more securely than common nails but wet wood will loosen the cement coating in a matter of days. Threaded or ring shank nails loose their holding power when subjected to sudden pressure (e.g. staircases) which can cause a thread to pop with each shock. Therefore a twist or spiral shank nail will have the best holding power.

Procedure:

Each group will use a 2X4X12 long and drive one each of the following nails into the edge of the 2X4 at the locations shown below.


The nails to be driven are as follows:

16d Smooth 16d Cement Coat 16d Ringed Shanked 16d Spiral shank 16 Cement Coat pneumatic nailer 2”x 7/16“ Crown Stapler

All nails should be seated with ¾ “to 1” of the head above the 2X4 so that they can be secured in the AST universal tester. Using a crosshead speed of .5 to 1 inch per minute, pull each nail until maximum force is displayed then move on to the next until all have been tested. Use spacer blocks provided for setting nails from the nail gun and stapler.

CON 251 Lab #5Holding Force of Framing Nails

Type of Nail Force Applied to Pull out Nail # 1 lbs.

Nail # 2 lbs.


Nail # 3 lbs.

Nail # 4 lbs.

Nail # 5 lbs.

Nail # 6 lbs.

1. Based on your test results, briefly explain which Nail proved to withstand the greatest pullout force?

2. Why do you believe this is the best fastener?

3. Setting the nails into the wood can cause splitting, how can this affect holding force of the nails?

4. How can moisture content and type of wood affect holding force of the nails?

CON 251 Lab #6Impact Strength of Flooring & Underlayment

Introduction:

Subfloor versus Underlayment

The terms "subfloor" and "underlayment" are often used interchangeably, but there is a world of difference between the two. A subfloor is a layer intended to provide structural support. Underlayment, on the other hand, is installed over a subfloor to create a smooth, durable surface upon which finish flooring is installed.


Resilient floor coverings demand a lot from underlayments. These underlayments must be hard, smooth, dimensionally stable and stiff. Hardboard, plywood and at least one OSB product offer smooth, hard surfaces that are considered safe for thin resilient flooring. Other popular choices are particleboard and American Plywood Association's (APA) Sturd-I-Floor, a hybrid system that combines subflooring and underlayment functions in a single panel product.

Particleboard

Particleboard is smooth, knot-free, and hard. It has no core voids and has great impact resistance. Sounds like a winner! But the RFCI doesn't recommend its use for fully adhered sheet vinyl or tile floors.

Thickness edge-swelling is the number one complaint when it comes to particleboard installed under resilient flooring. Particleboard soaks up moisture at its edges first, creating ridges in the finish flooring.

If vinyl tiles are used, they create a finish floor with many seams. These seams can expose particleboard underlayment to wetting and swelling when the floor is washed. Here, wood fibers will swell and tiles will lift around their edges. Particleboard is not a strong candidate for underlayment in moist locations like basements and bathrooms.

Rich Margosian, general manager with National Particleboard Association (NPA) claims, "The biggest problems are usually related to installation." Examples leading to failure include laying particleboard underlayment:

before the structure is weathertight over unvented crawlspace

over crawlspace without a groundcover

improperly stored on site (store flat & keep dry)

before plaster and concrete have cured dry


If particleboard is used, a glue-nail fastening system will produce the best results. White carpenter's glue, not subfloor adhesive, is recommended by NPA. Spread the glue onto the subfloor with a paint roller and then nail down the panels.

OSB

While there are over a dozen APA-approved oriented strand board (OSB) subfloor and sheathing products, there are no APA-approved OSB underlayment products. Only one manufacturer, Weyerhauser, seems to be seeking APA approval for their 1/4-inch OSB underlayment, Structurwood. The lack of APA approval for Structurwood appears to be a procedural technicality based on the fact that APA just hasn't developed a standard for non-plywood underlayment yet. APA and Weyerhauser promise a standard is in the works. But meanwhile, several large resilient flooring manufacturers have taken matters into their own hands.

Some companies have tested and approved Structurwood for use under fully-adhered and perimeter-bonded floors. Weyerhauser backs its product with a one-year warranty.

Surface smoothness can be a problem with OSB underlayment because strands lying next to each other in the panel's matrix may shrink and swell differently. The irregular surface will telegraph through thin resilient flooring. Weyerhauser claims to have solved this riddle with a proprietary stabilizing and conditioning process.

APA Plywood

Tried-and-true is appealing in an environment where everyone wants to blame the other guy for problems that might arise. Plywood gets a clean bill-of-health from everyone. All resilient flooring manufacturers approve the use of appropriately-graded APA plywood under all types of resilient flooring, provided it is installed correctly


>Approved plywood underlayments for resilient floor coverings have the following characteristics noted in their grade standards or stamp markings

"underlayment" or "plugged crossbands" exposure classification

o Exposure 1 - limited exposure to moisture

o Exterior - repeated exposure to moisture

fully sanded face (not PTS, plugged and touch-sanded)



Procedure

The purpose of this lab activity is to do relative comparison of the impact strength of three different sub-flooring and underlayment materials. The materials used for this test are: 19/32” OSB (oriented Stranded board), 19/32” particleboard, and 19/32” CD plywood. There are several ASTM test standards for impact testing of wood-based floor and roof sheathing. The two standard tests are ASTM E-661-88 and E-695-79. Both of these tests are conducted with a leather bag filled with lead or steel shot to a weight of 30 lbs. Both tests are rather complicated and the apparatus for the tests are not really practical to build. We will use ASTM D-143 A modified Hatt-Turner Test. This test is a flexural impact test normally used for solid wood samples. (refer to page 542 in text for more information) We will use a falling dart that weighs 5 lbs. And will be dropped from .5 feet to up to 9 feet which will generate a total of 45 lbs of impact.

Procedure:

1. Place sample in steel holding fixture.

2. Raise falling dart to .5 feet and release rope allowing dart to impact test specimen. (note any permanent deformation of fracture)

3. Repeat test raising dart in .5 foot increments until fracture or permanent deformation occurs.

4. Examine failure location on specimen and note any internal voids or defects that may have contributed to the specimen failure. Record impact failure value and comments.

5. Repeat the above test procedures to the other specimens.


Specimen Type

Impact Load

Comments

Food for Thought

A Traditional king sized waterbed is 6’ X 7’ and approximately 12” deep. The pedestal base under the waterbed is recessed 6” on all sides, and supports the weight of the waterbed. The weight of water is approximately 62.42 lbs per cubic foot. And contains approximately 7.48 gallons per cubic foot.

1. How many gallons of water are in the waterbed?

2. What is the load per square foot that the waterbed is exerting on the floor?

An upright 22 cubic foot freezer located in a kitchen is approximately 24” X 24” X 6’ high. You recently purchased a whole Angus beef and had it cut and wrapped. The total weight of the beef was 750 lbs cut and wrapped. The weight of the freezer empty was 150 lbs. Screw casters on the bottom of the freezer are located on the corners and are 1-1/2” in diameter. What is the load in lbs per square foot of the freezer on the kitchen floor?

A homemaker wearing ½” diameter high heel shoes weighs 150 lbs. The homemaker reaches for a bowl on a top shelf, raising one leg to stretch is supported only by one heel. What is the load that is being applied to the floor in lbs per sq. ft.

A snowstorm in spring of 2003 dropped 28” of snow in Ft. Collins. The moisture content of the snow was 4:1 (4” of snow yields 1” of water.) A newly constructed 40’ X 60’ metal building with a relatively flat roof collapsed. What was


the total weight load on the roof, and what was the load per sq. foot? (Reference information is in the first problem)

Total load Load per sq. foot.


CON 251 Lab #7Holding Strength of Construction Adhesive on Sub-

flooring

I. Introduction

Construction adhesive refers to a broad range of similar products used to bond common materials used in the construction, renovation and finishing of homes. Of course, if you have shopped in a hardware store you know that some companies have adhesives they have named "construction adhesive". In the context of this article, I am speaking of a class of adhesives that share certain properties. The basic characteristics of these products are:Available in cans, squeeze tubes, and caulking tubesThick pasty consistency; applied with putty knife or notched trowelWater or solvent basedCan fill gaps and imperfections in materialsWill adhere to a wide range of building materialsTend to remain flexible after dryingWaterproof or water-resistantUsually dry within 24 hoursChoosing the correct construction adhesive product can be confusing, since there is lots of functional overlap among them. Fortunately, the manufacturers are pretty good about listing the uses of their products on the labels. Some of them are quite specific... "For ceramic tile only", for example. Others label their products for broader uses... the more generic and well-known "construction adhesive", a generalist that can be used for wide range of adhesive tasks. Some construction adhesives that work wonderfully on indoor wood will not stand up to the moisture and temperature changes of exterior work. You only get to choose once, so choose wisely.There are two ways construction adhesive is applied. These are in beads or full coverage. Beads are lines of adhesive that are applied to a surface with the use of a caulking gun. This is the most economical use of construction adhesive and is used for the gluing of large, flat materials to large flat surfaces. Some common uses for the bead method are in


the installation of plastic tub surrounds over drywall or ceramic tile, wood paneling to any smooth wall, attaching drywall to studs and securing sub flooring to floor joists. Full coverage is used where the material to be glued is small, such as floor tiles or ceramic tile, or where an absolutely solid surface is required, which includes virtually all flooring applications with the exception of carpet over padding and some types of vinyl flooring.All full coverage adhesive jobs require the use of a notched trowel to apply the adhesive. You may be tempted to just slather the adhesive on with a putty knife... and you might get away with this for a small repair. But there are five sensible reasons for doing it right, though the product labels won't tell you why... they just say to do it their way or else! In a nutshell,...Saves adhesive... using a notched trowel can save you up to 50% on the adhesive used over a flat trowel or wide putty knife!Consistent thickness of adhesive... Remember that most construction adhesives tend to stay flexible. Applying too thick an application can cause a soft spot in the floor, producing movement in the material. This may not be as critical with interlocking wood parquet flooring but it can be a disaster with ceramic tile!Shortens drying time... those little grooves flatten when the material is pressed into the adhesive giving a thinner glue film. Thinner coats mean less drying time. An overly thick adhesive coat can take weeks to dry properly.Better adhesion... the "peaks" produced by troweling increase the chance that the material will grip firmly to the adhesive. Less shrinkage... as the adhesive dries, it will shrink. This is not an issue with a thin coat. But if a thick layer is applied, the material you are gluing may noticeably move or settle! This is why you should never build up a depression in a floor or wall with adhesive alone... use a floor leveler or wallboard compound to flatten the surface before your gluing effort!Be careful when choosing a construction adhesive!! Certain applications and materials require special construction adhesives. Plastics are especially sensitive to poor adhesive choices! So when installing products such as


tub surrounds and vinyl cove base, be sure to use an adhesive recommended by the manufacturer. Otherwise, you may find that the adhesive's solvent will actually migrate through the plastic, causing noticeable staining on the surface! This solvent "creep" can be a sneaky process... it could take weeks to occur, long after the job is done. Needless to say, you will not be a happy camper!Note the drying times on the packaging! Construction adhesives in many cases do not reach full strength for a week; so if you want the job to last give them plenty of drying time!One of the more popular lines of construction adhesive is manufactured by the PL Company. Their line includes the old favorite PL200 general-purpose construction adhesive, as well as special formulations for plastics and foam and an exterior wood-flooring adhesive purported to be as "strong as nails"! Another major player in this area is Macco, manufacturer of Liquid Nails, a full line of construction adhesives for virtually all materials, indoor and out.

Recommended Application of construction adhesive:

1. Surface must be clean, structurally sound and free from excessive water. Can be applied in temperatures as low as 10°F depending on type of adhesive. Should be conditioned to 40°F before use.

2.3. Cut nozzle at 45° to the desired bead diameter,

usually ¼” to 5/16”.

4. Puncture inner seal with nail or wire.

5. Run adhesive beads slightly past the length and width of the sheet of sub flooring. Do not lay more adhesive than can be covered in fifteen minutes.


(Scrape off any adhesive that has set for more than 15 minutes or that has skinned over.)

6. Where sheets butt along the joist, lay adhesive in a zigzag pattern to include both sheets.

7. Space the adjoining sheet the thickness of a putty knife to allow for expansion.

8. Nail sheets in place with 8d-ringed shank or spiral shanked nails, spaced 12” on center of each joist.

9. Sub-flooring must be under roof within six weeks.

Testing procedures:

Set up AST testing machine with the appropriate fixtures. Set crosshead speed at .5 inches per minute and pull sub-flooring from joists. Record maximum load for each sample withstood at failure.


Adhesive Brand Type/Grade Solvent Base

Load0 min

Load15 min

Load30 min

LoadWet

Remarks


1. From the tests, what can be concluded about the delayed set time of construction adhesives?

2. How can this failure be minimized in the field?

3. What effects can moisture have in the adhesive properties of construction adhesives?


CON 251 Lab #8Threaded Fasteners and Shear Strength

I. IntroductionThreaded fasteners comprise a majority of the assembly

techniques used in the manufacturing and construction industries. While specifications of some of the fasteners vary between the two industries, the end result is the same, the joining of materials. In the manufacturing industries, typical fasteners used for assembly of components of subassemblies include but are not limited to bolts, nuts and bolts, machine screws, self-tapping machine screws and sheet metal screws. While the list is quite extensive, fasteners in manufacturing can be categorized in two main categories. They are machine screws and machine bolts.

Machine screws are typically less than ¼” in diameter and are sized by a number such as a # 10 machine screw which happens to be 3/16” in diameter. Sizes range from 0-80 to #10. There are also special sizes on either end of this spectrum such as a 00-96 or #12. The other criteria used for sizing machine screws are whether they are a course or fine pitch thread. For each # size there exists a fine and course thread. These thread pitches are identified as Unified National Fine or Unified National Course thread. Usually referred to as UNC or UNF. An example would be #10-32 UNF or 10-24 UNC. The head configuration of machine screws can be slotted; Phillips, Torx, or socket headed Allen. Other specialty head configurations are also available for tamper resistant fasteners found in restrooms and other public places.

Machine bolts are listed by there nominal diameter as a fraction, such as ¼” or ¾” Bolt and also have both course and fine thread configurations. Examples of these configurations are, ¼”-20 UNC or ¼” 28- UNF. Head configurations also vary with machine bolts. Most fasteners will be either hex head, socket head Allen, or Torx. Other specialty fasteners may have different head configurations. The standards for these mechanical fasteners is established by SAE and ANSI (Society of automotive engineers and American National Standards Institute.) These fasteners are made in different grades from grade 2 to 8, which corresponds to their tensile strength and material type. Specific grades and their representative symbols will be listed later in this document.


Fasteners used for structural applications in the construction industry are categorized differently than machine bolts. The standards for the construction industry are established by ASTM (American Society of Testing Materials) While there is some cross over in classifications, the markings are distinctly different that standard machine bolts. Specific grades and their representative symbols will be listed later in this document. Regardless of the type of fastener, there are similar stresses that are applied the fasteners when they are used. The first example is that fasteners can be subjected to tensile loads in which they are pulled apart or elongated. Bolts can also be subjected to Torsion or twisting loads, and they can also be subjected toe shear stresses in which they are sheared at right angles to their central axis. The shear stresses can be categorized as either a single or double shear depending on the type of application. See the illustration below for examples of each.

Modes of Failure in Bolted Shear Connections:a. Failure of the fastener fv = P/A (single shear) fv = P/2A (double shear)


In structural steel applications, the fasteners used are typically of one of two types. They are either standard hex headed bolts with structural nuts and washers, or they are Tension controlled bolts that are pre-torqued with a pneumatic or electric drive tool. Upon tightening, the bolt is not tightened by the head, but by a spline on the end of the bolt. When the maximum amount of torque is applied to the bolt, the spline separates from the bolt. Standard bolts and nuts must be tightened with a torque wrench to a specific load. Applying maximum torque to the bolt insures that its maximum clamping force will be applied to the assembly.

Hex Head Bolt MarkingsThe strength and type of steel used in a bolt is supposed to be indicated by a raised mark on the head of the bolt. The type of mark depends on the standard to which the bolt was manufactured. Most often, bolts used in machinery are made to SAE standard J429, and bolts used in structures are made to various ASTM standards. The tables below give the head markings and some of the most commonly needed information concerning the bolts. For further information, see the appropriate standard.


SAE Bolt DesignationsSAE

GradeNo.

Sizerange

Tensilestrength,

ksi MaterialHead

marking1

2

1/4 thru 1-1/2

1/4 thru 3/47/8 thru 1-1/2

60

7460

Low or mediumcarbon steel

5 1/4 thru 11-1/8 thru 1-

1/2

120105

Medium carbon steel,

quenched & tempered

5.2 1/4 thru 1 120 Low carbonmartensite steel,

quenched & tempered

7 1/4 thru 1-1/2 133 Medium carbonalloy steel,quenched & tempered

8 1/4 thru 1-1/2 150 Medium carbonalloy steel,quenched & tempered

8.2 1/4 thru 1 150 Low carbonmartensite steel,

quenched & tempered

ASTM Bolt DesignationsASTM

standarSize

rangeTensile

strength,Material Head

marking


d ksiA307 1/4 thru 4 60 Low carbon steel

A325Type 1

1/2 thru 11-1/8 thru 1-

1/2

120105


quenched & tempered

A325Type 2

1/2 thru 11-1/8 thru 1-

1/2

120105

Low carbonmartensite steel,

quenched & tempered

A325Type 3

1/2 thru 11-1/8 thru 1-

1/2

120105

Weathering steel,quenched & tempered

A449 1/4 thru 11-1/8 thru 1-

1/21-3/4 thru 3

12010590


quenched & tempered

A490Type 1

1/4 thru 1-1/2

150 Alloy steel,quenched & tempered

A490Type 3

1/4 thru 1-1/2

150 Weathering steel,quenched & tempered

Often one will find "extra" marks on a bolt head--marks in addition to those shown above. Usually these marks indicate the bolt's manufacturer. ASTM A325 Type 2 bolts have been discontinued, but are included above because they can be found in existing structures. Their properties can be important in failure investigations. While the bolts shown above are among the most common in the U.S., the list is far from exhaustive. In addition to the other bolts document.doc Page 46

covered by the SAE and ASTM standards, there are a host of international standards, of which ISO is perhaps the most well known.

Specifications

Tension Control BoltsAvailable from Textron Fastening Systems

Nucor® Tru-Tension® AssembliesFeatures

- Preassembed bolt and washer packaged with heavy hex nut

- Installed with lightweight, electric drive tool

- Bolt is calibrated so the spline tip twists off when the proper bolt

tension is achievedSupplied as ASTM A325 or ASTM

A490 Grade bolts- Made in the USA

Benefits- Speeds assembly- More ergonomic installation over

pneumatic wrenches- Easier traceability than

components sold separately- Visual inspection is normally all


that is required to determine proper tension

Performance and Technical Data: View a tech data sheet from Nucor Fastener Division

Type

Description

Material Descripti

on

Surface

Finish

Identification

Marking*

Head Style

s

Available

Diameters

Available

Lengths

A325

F1852 splined

bolt, heavy hex nut

and F436 washer

assembly

carbon steel,

quenched and

tempered

plain round 3/4" to 1-1/8" up to 6"

A490

F1852 splined

bolt, heavy hex nut

and F436 washer

assembly

medium carbon

alloy steel, quenched

and tempered

plain round 3/4" to 1-1/8" up to 6"

F593, F594 - ASTM F593 is a specification for stainless hex head cap screws: ASTM F594 is for stainless nuts. Compared to regular (18-8) stainless fasteners, F593 and F594 call for: (a) tensile requirements about 20% higher than that of commercial 18-8 or stainless hex caps and nuts to MS Specifications (MS35307-8, MS34649-50); (b) both a minimum and a maximum tensile and hardness requirements while commercial and MS fasteners do not have a maximum; (c) chemical requirements that (eliminate) many commonly used mixtures of 300 or 18-8 stainless while allowing others. (courtesy Star Stainless Screw)

Full Size Tests Machined Specimen Tests

Stainless Alloy Group

ConditionAlloy MechanicalProperty Marking

NominalDiameter

TensileStrengthksi c

YieldStrengthksi c/d

RockwellHardness

TensileStrengthksi d

YieldStrengthksi c/d

Elon-gationin 4D %

303, 304, 305, 384,

CW1 F593 C 1/4 to 5/8 100 to 150

65 B95 to C32

95 60 20


http://www.nucor-fastener.com/tds006.gif

XM1, XM7,302Se CW2 F593 D 3/4 to1-

1/2 85 to 140 45 B80 to C32 80 40 25


CON 251 Lab #8Double Shear Test of Threaded Fasteners

Shear Strength = Load @ Rupture 2X Cross Sectional Area of Bolt

(Note 1: The shear strength of a fastener is equal to approximately 80% of its rated tensile strength value.Note:2 Cross sectional area thru the threads are: Stress area of a ¼-20 UNC is 0.0318 sq. in. Stress area of a ¼-28 UNF is 0.0364 sq. in.)Sample # 1 Type and Grade 1 & 2 or A307 Carriage Bolt Diameter Peak Load at Rupture Shear Strength psi.Listed Tensile Strength of this fastener ksiApproximated shear strength value ksi

Sample # 2 Type and Grade 1 & 2 or A307 Bolt Diameter Peak Load at Rupture Shear Strength psi.Listed Tensile Strength of this fastener ksiApproximated shear strength value ksi

Sample # 3 Type and Grade 5 or A325 Diameter Peak Load at Rupture


Shear Strength psi.Listed Tensile Strength of this fastener ksiApproximated shear strength value ksi

Sample # 4 Type and Grade 8 or A490 Diameter Peak Load at Rupture Shear Strength psi.Listed Tensile Strength of this fastener ksiApproximated shear strength value ksi

Sample #5 Type and Grade F593 SS Diameter Peak Load at Rupture Shear Strength psi.Listed Tensile Strength of this fastener 100 - 150 ksiApproximated shear strength value ksi

Sample # 6 Type and Grade Allen Socket Cap Screw Diameter Peak Load at Rupture (Thru the threads)Shear Strength psi. (Thru the threads)Peak Load at Rupture (Thru the body)Shear Strength psi. (Thru the body)Listed Tensile Strength of this fastener 180 ksiApproximated shear strength value ksi


Type and Grade Grade 5 Diameter & Pitch ¼-20 & ¼-28 Listed Tensile Strength of this fastener ksiApproximated shear strength value ksiFine thread Peak Load at Rupture

Shear Strength psi.Course Thread Peak Load at Rupture

Shear Strength psi.


CON 251 Lab #9Concrete Compression Testing

I. Introduction

Concrete (construction), artificial engineering material made from a mixture of Portland cement, water, fine and coarse aggregates, and a small amount of air. It is the most widely used construction material in the world.Concrete is the only major building material that can be delivered to the job site in a plastic state. This unique quality makes concrete desirable as a building material because it can be molded to virtually any form or shape. Concrete provides a wide latitude in surface textures and colors and can be used to construct a wide variety of structures, such as highways and streets, bridges, dams, large buildings, airport runways, irrigation structures, breakwaters, piers and docks, sidewalks, silos and farm buildings, homes, and even barges and ships.Other desirable qualities of concrete as a building material are its strength, economy, and durability. Depending on the mixture of materials used, concrete will support, in compression, 700 or more kg/sq cm (10,000 or more lb/sq in). The tensile strength of concrete is much lower, but by using properly designed steel reinforcing, structural members can be made that are as strong in tension as they are in compression. The durability of concrete is evidenced by the fact that concrete columns built by the Egyptians more than 3600 years ago are still standing.

II. Composition

The two major components of concrete are a cement paste and inert materials. The cement paste consists of portland cement, water, and some air either in the form of naturally entrapped air voids or minute, intentionally entrained air bubbles. The inert materials are usually composed of fine aggregate, which is a material such as sand, and coarse aggregate, which is a material such as gravel, crushed stone, or slag. In general, fine aggregate particles are smaller than 6.4 mm (.25 in) in size, and coarse aggregate particles are larger than 6.4 mm (.25 in). Depending on


the thickness of the structure to be built, the size of course aggregate particles used can vary widely. In building relatively thin sections, a small size of coarse aggregate, with particles about 6.4 mm (.25 in) in size, is used. At the other extreme, aggregates up to 15 cm (6 in) or more in diameter are used in large dams. In general, the maximum size of coarse aggregates should not be larger than one-fifth of the narrowest dimensions of the concrete member in which it is used.When portland cement is mixed with water, the compounds of the cement react to form a cementing medium. In properly mixed concrete, each particle of sand and coarse aggregate is completely surrounded and coated by this paste, and all spaces between the particles are filled with it. As the cement paste sets and hardens, it binds the aggregates into a solid mass.Under normal conditions, concrete grows stronger as it grows older. The chemical reactions between cement and water that cause the paste to harden and bind the aggregates together require time. The reactions take place very rapidly at first and then more slowly over a long period of time. In the presence of moisture, concrete continues to gain strength for years. For instance, the strength of just-poured concrete may be about 70,307 g/sq cm (1000 lb/sq in) after drying for a day, 316,382 g/sq cm (4500 lb/sq in) in 7 days, 421,842 g/sq cm (6000 lb/sq in) in 28 days, and 597,610 q/sq cm (8500 lb/sq in) after 5 years.Concrete mixtures are usually specified in terms of the dry-volume ratios of cement, sand, and coarse aggregates used. A 1:2:3 mixture, for instance, consists of one part by volume of cement, two parts of sand, and three parts of coarse aggregate. Depending on the applications, the proportions of the ingredients in the concrete can be altered to produce specific changes in its properties, particularly strength and durability. The ratios can vary from 1:2:3 to 1:2:4 and 1:3:5. The amount of water added to these mixtures is about 1 to 1.5 times the volume of the cement. For high-strength concrete, the water content is kept low, with just enough water added to wet the entire mixture. In general, the more water in a concrete mix, the easier it is to work with, but the weaker the hardened concrete becomes.Concrete can be made to have any degree of water tightness. It can be made to hold water and resist the penetration of wind-driven rains. On the other hand, for purposes such as constructing filter beds, concrete can be made porous and highly permeable.


Concrete can also be given a polished surface that is as smooth as glass. By using heavy aggregates, including steel fragments, dense concrete mixtures can be made that weigh 4005 or more kg/cu m (250 or more lb/cu ft). Concrete that weighs only 481 kg/cu m (30 lb/cu ft) can be made by using special lightweight aggregates and foaming techniques. Forms consisting of such lightweight aggregates can be floated on water, sawed into pieces, or nailed to another surface.For small jobs and minor repairs, concrete can be mixed by hand, but machine mixing ensures more uniform batches and, therefore, superior performance. For most home repairs and improvements—for example, floors, walks, driveways, patios, and garden pools—the recommended proportion is a 1:2:3 mix.After exposed surfaces of concrete have hardened sufficiently to resist marring, they should be cured by sprinkling or ponding (covering) with water or by using moisture-retaining materials such as waterproof paper, plastic sheets, wet burlap, or sand. Special curing sprays are available. The longer concrete is kept moist, the stronger and more durable it will become. In hot weather, it should be kept moist for at least three days. In cold weather, drying concrete must not be allowed to freeze. This can be accomplished by covering the cement with a tarpaulin or some other material that helps trap the heat generated by the chemical reactions within the concrete that cause it to harden.

III. Construction Techniques

Concrete is poured into place in a number of ways. For the footings of small buildings, the wet concrete is poured directly into trenches dug into the earth below frost level. Concrete for foundations and certain types of walls is placed between supporting wood or metal forms, which are removed after the concrete has hardened. In lift-slab construction, floors and roof slabs are cast at ground level and then raised by hydraulic jacks and fastened to columns at the desired elevation. Slip forms are used to produce vertical shafts for silos and the cores of buildings. They are moved upward at a rate of 15 to 38 cm (6 to 15 in) per hour while concrete and reinforcements are put in place. The tilt-


up method of construction is frequently used for one- and two-story buildings. Walls are cast in place on the ground or on the previously laid concrete floor and tilted into position by cranes. The walls are joined at the corners or between panels with cast-in-place concrete columns. To pave a highway or road with concrete, a slip-form paver is used. Two metal side forms are connected to a slip-form paver. A layer of concrete is poured between the side forms as the paver slowly moves forward on its treads; the side forms keep the concrete in position as it dries. Slip-form pavers can lay continuous strips of one or two lanes of concrete pavement.For certain applications, such as the construction of swimming pools, canal linings, and curved surfaces, concrete may be applied by the shotcrete method. In shotcreting, concrete is sprayed under pneumatic pressure rather than placed between forms. Often the use of shotcrete eliminates the need for formwork and permits placement of concrete in confined areas where conventional forms would be difficult or impossible to construct.Air-entrained concrete is concrete in which minute air bubbles are intentionally trapped by the addition of an admixture to the cement, either during its manufacture or during the batching and mixing of the concrete. The presence of a properly distributed amount of these bubbles imparts desirable properties to both freshly mixed and hardened concrete. In freshly mixed concrete, entrained air acts as a lubricant, improving the workability of the mix, thereby reducing the amount of water that needs to be added. Entrained air also reduces the need for fine material (sand).Entrained air in hardened concrete dramatically reduces the scaling that might otherwise result from the use of chemicals to melt ice on roads and streets. It also prevents damage to pavements caused by freezing and thawing. The air bubbles function as minute safety valves by providing room for the free water in concrete to expand harmlessly as freezing occurs.

IV. Concrete Masonry

Concrete masonry is block and brick building units molded of concrete and used in all types of masonry construction. Concrete masonry is used for load-bearing and nonload-bearing walls;


piers; partitions; fire walls; backup for walls of brick, stone, and stucco facing materials; fireproofing over steel structural members; firesafe walls around stairwells, elevators, and other enclosures; retaining walls and garden walls; chimneys and fireplaces; concrete floors; and many other purposes.About 60 percent of all concrete masonry units, such as cinder blocks, are made with lightweight aggregates. Processed clays, blast-furnace slag, shales, natural volcanic aggregates, and cinders are the lightweight aggregates most commonly used. The size of the masonry unit most commonly used for walls, both below and above ground, is 20 by 20 by 40 cm (8 by 8 by 16 in). Masonry units are laid horizontally, and are cored to reduce weight and to provide an insulating air space within the block. New types of concrete masonry, such as split and slump block, are being used as facing in homes, commercial buildings, schools, churches, and municipal facilities.Basic block types are fairly well standardized today. Specific types can usually be supplied for any construction without cutting or fitting. Special molds are available for the production of patterned shadow effects on exterior and interior block walls. It is possible to supply virtually any color or type of texture.

V. Reinforced Concrete

Concrete used in most construction work is reinforced with steel. When concrete structural members must resist extreme tensile stresses, steel supplies the necessary strength. Steel is embedded in the concrete in the form of a mesh, or roughened or twisted bars. A bond forms between the steel and the concrete, and stresses can be transferred between both components.Prestressing concrete has removed many limitations on the spans and loads for which a concrete structure can be economically designed. The basic function of pre-stressing is to greatly reduce the tensile stresses to which crucial areas of concrete structures are subjected. Prestressing is accomplished by stretching high-strength steel to induce compressive stresses in concrete. The strengthening effect of compression in concrete acts like horizontally squeezing a row of books. When you apply sufficient pressure to the books at each end, you induce compressive stresses throughout the entire row; thus, although the center


volumes are unsupported, you can lift the books and carry them horizontally.Compressive stresses are induced in pre-stressed concrete by either pretensioning or post-tensioning the steel reinforcement. In the pretensioning process, the steel is stretched before the concrete is placed. After the concrete has hardened around the tensioned reinforcement, the stretching forces are released. The steel shortens somewhat, and because of the bond between the steel and concrete, the compressive stress in the concrete increases. In post-tensioning, the concrete is cast around, but not in contact with, un-stretched steel. The steel is stretched after the concrete has hardened by anchoring one end against the concrete and using hydraulic jacks to pull the other. After stretching, the second end is also anchored, compressing the concrete.

Test Procedures:

Each class made three samples of three different aggregate sizes. All samples we fully cured for 28 days to achieve optimal strength. The significances of this test is to demonstrate how aggregate size impacts the compressive strength of concrete.Test procedures will be the same for all samples.

In the test data, record the load at failure of the three different samples of each aggregate size. Average the load at failure and then calculate the average compressive strength of each aggregate size.


CON 251 Lab #9Compression Testing Concrete Cylinders

Test DataSlump Slump

0” – 1”Slump

1-1/2” – 3”Slump6” – 9”

Load atFailure

Sample #1Load atFailure

Sample #2Load atFailure

Sample #3Average Load at Failure

Cross Sectional

AreaAverage

Compressive

Strength psi

Compressive Strength = Load at Failure Cross Sectional Area

Cross Sectional Area = π X R2

1. What is the significance of the size, shape and texture of aggregate as compared to the strength of the concrete?


2. What is the significance of the slump as compared to the strength of the concrete?

3. Why is there a decrease in strength of concrete if it is allowed to freeze during curing?

4. What is hydration and how does it effect the curing of concrete?


CON 251 Lab #10Flexural Strength of Concrete

Introduction

Flexural Strength is the ability of a beam or slab to resist failure in bending. It is measured by loading concrete beams with a span three times the depth. The flexural strength is expressed as “Modulus of Rupture” (MR)

Flexural Strength is about 10 to 20% of compressive strength. However, the best correlation for specific materials is obtained by laboratory tests.

Sample Preparation

Flexural strength specimens shall be rectangular beams of concrete cast and hardened with long axes horizontal. The length shall be at least 2 in. greater than three times the depth as tested. The ratio of width to depth as molded shall not exceed 1.5. The standard beam shall be 6 in. in cross section, and shall be used for concrete with maximum size coarse aggregate up to 2 in.. When the nominal maximum size of the coarse aggregate exceeds 2 in. , the smaller cross sectional dimensions for the beam shall be at least three times the nominal maximum size of the coarse aggregate. Unless required by the project specifications, beams made in the field shall not have a width or depth of less than 6 in.

1. Scope:

This test is for determining flexural strength of concrete with third point loading.


2. Procedure:

a. Turn the test specimen on its side, with respect to its position as molded, and center on the bearing blocks.

b. Bring the load-applying blocks in contact with the surface of the Specimen.

c. If full contact is not obtained at no load between the specimen and the load-applying blocks, grind the contact surfaces of the specimen or shim with leather strips.

d. Load at a rate of 125 to 175 psi/min

e. Measure the beam at the breaking point to obtain the width and depth to nearest 1/16" (1 mm) with respect to its position when tested.

f. Record the load in lbs.

3. Report:

Calculations for (modulus of rupture)

R = Pl/bd2

Where:

R = modulus of rupture, psi


P = maximum applied load indicated by the testing machine, lbs.

l = span length, in., (or mm),

b = average width of specimen, inches d = average depth of specimen, inches

Report the flexural strength to the nearest 10 psi.

5. References: ASTM C 78-02



CON 251 Lab #10Flexural Strength of Concrete

(Flexural modulus)

Un-Reinforced

Reinforced Below Neutral Axis

P (load)l (span)b (width)d (depth)R ( MR) psi

R = Pl/bd2

Where:

R = modulus of rupture (MR), psi

P = maximum applied load indicated by the testing machine, lbs.

l = span length, in., (or mm),

b = average width of specimen, inches d = average depth of specimen, inches

1. What were the results of loading the unreinforced beam?


2. What were the results of the sample with the rebar located below the neutral axis?

3. What results would you expect to see if rebar were placed above and below the neutral axis in the specimen?


CON 251 Lab #11Flexural Properties of Laminated and Solid Floor Joists

I. Introduction

Trus Joist’s Silent Floor® System continues to set the standard for engineered solutions to residential framing challenges. At the heart of the system is the TJI® joist, which was created and marketed by Trus Joist more than 25 years ago as the first commercially available wood “I” joist. Over the past quarter century, we have continued to test, develop and improve our product line with more than 400 refinements in order to better serve our customers, while more efficiently utilizing forest resources.

A healthy future for the building industry depends on sustaining a predictable supply of wood fiber—fiber Trus Joist uses to develop structural building products. In the face of a diminishing supply of quality structural lumber and changing forest resources, Trus Joist is dedicated to giving you top quality products that optimize wood fiber utilization. Our goal is to provide you with the best possible products today, through advanced manufacturing technology and resource utilization that also assure you the best possible products tomorrow.

Understanding Floor NoiseAny homeowner knows there are many sounds that

emanate from a house’s walls and floors: boards creakand squeak, ductwork flexes and nails rub. In manycases, these noises are difficult to prevent and shouldbe expected.

However, there is a cure for the most common causeof floor squeaks—the inconsistent size of sawn lumber.Floor joists of sawn lumber are unlikely to be the samedepth when they’re installed, and subsequent dryingcan magnify unevenness. When floor sheathing flexes over these joists, squeaks occur.


The Silent Floor® Joist, on the other hand, is manufactured to precise specifications to ensure that all joists are the samedepth and won’t shrink after installation. The natural defects found in sawn lumber are engineered out, and dimensionalstability is manufactured in. Using the Silent Floor® Joist virtually eliminates floor noise caused by dimensional instability.A builder that uses the Silent Floor® Joist has made a significant effort to eliminate annoying floor squeaks. While it won’tprevent all the normal sounds that come from a structure, homes built with the Silent Floor® Joist are much quieter thanthose framed with sawn lumber. 3 Changing the Way You Build™

ASTM D 198-84Scope of Flexure Test

These test procedures cover the determination of the flexural properties of structural members made of solid or laminated wood. The test method is intended primarily for beams of rectangular cross section but is also applicable to beams of round and irregular shapes, such as round posts, I-beams, or other special sections. Summary of Test Methods

The structural member, usually a straight or slightly cambered beam of rectangular cross section, is subjected to a document.doc Page 68

bending moment by supporting it near its ends, at locations called reactions and applying transverse loads symmetrically imposed between these reactions. The beam is deflected at a prescribed rate, and coordinate observations of loads and deflection are made until rupture occurs.


CON 251 Labs #11Flexural Properties of Laminated and Solid Floor Joists

Procedures for conducting flexural test on TJI laminated joists and solid dimensional members. Place specimen in Test fixture. Applied load to cross head at the rate specified. Observe indicator for deflection measurements and simultaneously record load values. Take for deflection and load measurements. Continue loading until rupture occurs. Record Peak load value. Repeat the same procedures for other sample.


TJI Deflection

Volts Load Deflection

Volts Load

#1#2#3#4

Peak Volts -------- -------

Solid #1#2#3#4

Peak Volts -------- --------

LVL/Microlam

#1#2#3#4

Peak Volts ------- ------- Sample #1 Sample #2


Calculations for Modulus of Rupture Sr (two point loading): Sr = 3Pa ÷ b(h2) Modulus of Rupture for TJI = Modulus of Rupture for Solid = Where P = Peak Load at Rupture

a = ½ shear span b = width of beam TJI= .943 Solid= 1.5 h = depth of beam TJI= 11.875 Solid= 11.25

Calculations for Shear Stress tm tm = 3P ÷ 4 (bh) (bh) for Solid 16.875 (bh) for TJI 11.200 Shear Stress for TJI = Shear Stress for Solid =


This test was to examine and compare the Shear Strength and flexural properties of two different floor joists. Sample one was the solid Douglas Fir 2X12 joist and the second a Engineered TJI 2X12 joist. (these questions pertain only to the comparison of TJI, Vs. Soild)

From the test results, which joist withstood the greatest loading before rupture?

From the test results, which joist displayed the best load to deflection ratio?

If defects were present in each sample, what significance did the defects have on the test results?

What is the advantage and disadvantage of each type of joist?


Reference Materials


Carbon Steel 10XX Plain carbon steel , Mn 1.00% max 11XX Resulphurised free cutting 12XX Resulphurised - Rephosphorised free cutting 15XX Plain carbon steel, Mn 1.00-1.65%

Manganese Steel 13XX Mn 1.75%Nickel Steel 23XX Ni 3.50%

25XX Ni. 5.00%Nickel Chromium Steel 31XX Ni 1.25%, Cr 0.65-0.80%

32XX Ni 1.75%, Cr 1.07% 33XX Ni 3.50%, Cr 1.50-1.57% 34XX Ni 3.00%, Cr 0.77%

Molybdenum Steel 40XX Mo 0.20-0.25% 44XX Mo 0.40-0.52%

Chromium Molybdenum Steel 41XX Cr 0.50-0.95%, Mo 0.12-0.30%Nickel Chromium Molybdenum Steel 43XX Ni 1.82%, Cr 0.50-0.80%, Mo 0.25%

47XX Ni 1.82%, Cr 0.50-0.80%, Mo 0.25%Nickel Molybdenum Steel 46XX Ni 1.05%, Cr 0.45%, Mo 0.20-0.35%

48XX Ni 0.85-1.82%, Mo 0.20-0.25%Chromium Steel 50XX Ni 3.50%, Mo 0.25%

51XX Cr 0.27-0.65% 50XXX Cr 0.80-1.05% 51XXX Cr 0.50% C 1.00% min 52XXX Cr 1.02%, C 1.00% minCr 1.45%, C 1.00%

Chromium Vanadium Steel 61XX Cr 0.60-0.95%, V 0.10-0.15%Tungsten Chromium Steel 72XX W 1.75%, Cr 0.75%

Nickel Chromium Molybdenum Steel 81XX Ni 0.30%, Cr 0.40%, Mo 0.12% 86XX Ni 0.55%, Cr 0.50%, Mo 0.20% 87XX Ni 0.55%, Cr 0.50%, Mo 0.25% 88XX Ni 0.55% Cr 0.50% Mo 0.35%

Silicon Manganese Steel 92XX Si 1.40-2.00%, Mn 0.65-0.85% Cr 0.65%Nickel Chromium Molybdenum Steel 93XX Ni 3.25%, Cr 1.20%, Mo 0.12%

94XX Ni 0.45%, Cr 0.40%, Mo 0.12% 97XX Ni 0.55%, Cr 0.20%, Mo 0.20% 98XX Ni 1.00%, Cr 0.80%, Mo 0.25%


Approximate Tensile Strength for Rockwell "C" scaleDiamond

BraleApproximate

Tensile Diamond

BraleApproximate

Tensile150 kg C

ScaleStrength 1,000

PSI150 kg C

ScaleStrength 1,000

PSI65 33 15464 32 15063 31 14662 30 14261 29 13860 28 13459 326 27 13158 315 26 12657 304 25 12456 294 24 12255 287 23 11854 279 22 11653 269 21 11352 261 20 11151 254 18 10750 245 16* 10249 238 14* 9848 232 12* 9247 225 10* 9046 219 8* 8745 211 6* 8344 206 4* 7943 202 2* 7742 198 0* 7441 191 7340 185 7039 181 6738 176 6537 171 6236 168 6035 163 5834 159 56


Concrete Cores and Beam Preparation

Purpose of this activity is to prepare concrete core and beam specimens in accordance with ASTM C31. During this lab activity 4’X8” cylinders will be molded to compare relative compressive strength of different aggregate sizes. Concrete beams will be molded to test for flexural strength. After molding cylinders and beams the specimens will cure for a full 28 days at which time they will be tested for there compressive strength and flexural modulus.

A slump test is prepared in accordance with (ASTM C 143). It has been determined that a slump of less than ½” may not be adequately plastic and concretes having slumps greater than 9” may not be adequately cohesive. In adequate amount of water will not allow full hydration of the cement and excessive amounts of water will dilute the cement. Both extremes will significantly weaken the strength of concrete. Under laboratory conditions with strict control of all concrete materials, the slump is generally found to increase proportionally with the water content of a given concrete mixture, and thus to be inversely related to the concrete strength.

Three sets of 4” X 8” concrete test cylinders will be prepared by the class. Each set of concrete cylinders will be molded using three different water to cement ratios determined by a slump test. After 28 days testing of these cylinders should indicate a change in compressive strength as the water to cement ratio changes.

1. Three cylinders will be molded out of a standard Quikrete mix. With a slump of 0” to 1”. (approx. 32 oz. water)

2. Three cylinders will be molded out of a standard Quikrete mix. With a slump of 1-1/2” to 3”. ( approx. 50 oz. water)

3. Three cylinders will be molded out of a standard Quikrete mix. With a slump of 6” to 9”. (approx. 60 oz. water)

4. Each cylinder shall be properly labeled on its lid stating, class section number and mix or slump and oz. of water.


Adequate water must be added to insure complete plasticizing but not excessive enough to exceed a 9” slump. Each plastic cylinder mold will be filled ½ full then rodded 25 times with a rounded end rod. The cylinder will then be filled to the top and rodded an additional 25 times. Using a rod or trowel, the cylinders should be leveled off and made smooth. Cylinders should then be capped with a plastic lid and labeled. This process will be repeated for all nine cylinders. They then will b e placed on a plywood panel and stored for 28 days.

Design mixes will be mixed by hand in a wheel barrow:

1. Measure our six quarts of Quikrete for each batch of three cylinders. (3- heaping 2qt. buckets)

2. Start by adding no more than 2 pints (1 quart or 32 oz.) of water.

3. Mix thoroughly with shovel or hoe.4. Perform Slump test and add additional water to achieve

desired slump. (No design mixes should contain more than 4 pints (2 quarts or 64 oz.) of water.

5. Record the actual total amount of water added to the mix on the lid.


Procedures for ASTM C-143 (Slump Test for Hydraulic Cement)

1. Start the test within 5 min. after obtaining the final portion of the mixed concrete sample.

2. Dampen the mold (inside) and place on the dampened base plate.

3. Hold the mold firmly in place during the filling and rodding operation (by the operator standing on the two foot pieces).

5. Fill the mold in three layers, each approximately one-third the volume of the mold.

5. Rod each layer with 25 strokes of the tamping rod. During filling and rodding the top layer, heap the concrete above the mold before rodding is started.

6. Strike off the surface by a screeding and a rolling motion of the tamping rod

7. Remove the mold immediately by raising it in a vertical direction. (Steps 2 through 7 should be completed in less than 2.5 minutes).

8. Place the empty mold (inverted) adjacent to the concrete sample and measure the vertical difference between the top of the mold and the displaced original center of the sample. This is the slump.


The concrete beams will be 6”X6”X20” in length. They will be molded using a standard Quikrete mix with a slump of between 2” and 3”. (2- 80lb. bags of Quikrete 5000 High Early Concrete Mix will make two beams and 3 compression cylinders))

1. One beam will be molded with no reinforcing bar.

2. One beam will be molded with a #3 reinforcing bar located below the neutral axis of the beam.

All beam molds will be filled half full then rodded 25 times. The mold will then be filled completely and then rodded an additional 25 times. Using a trowel or bar, level the top surface even with the top of the mold. Place molds in storage to cure for 28 days.

Be sure to rinse and clean all tools and equipment before returning to storage.


Sub-flooring Adhesive Testing Sample Preparation

This test is designed to simulate a variety of different conditions in which construction adhesives are applied in the construction industry as it pertains to the installation of sub-flooring. There are a variety of different variables that will be discussed during this lab that are dependent upon the type of adhesives used, and the conditions in which they are applied. Some or all of these variables may or may not affect the bonding properties (holding strength) of the adhesive. Four samples will be prepared to simulate some of these variables. Each sample must be properly labeled with the following information:

1. Class Section Number2. Brand Name of the adhesive, i.e. Liquid Nails, Locktite, etc.3. Type or grade, i.e. Pl 200, Sub-Flooring etc.4. Solvent Base, either water base or Petroleum based.5. Time or condition variable.

Each group then will need 2- precut 2X4 and 4- precut pieces of sub flooring. The procedures are as follows:

1. Lay bead of adhesive on one edge of the 2X4 and immediately place sub flooring on adhesive and nail at each end. Label that edge “0 Minutes”.

2. Turn over and lay a bead of adhesive on the edge of 2X4. Do not install sub flooring until 15 minutes has elapsed. Label that edge “15 Minutes”. After 15 minutes has elapsed the sub flooring can be installed and nailed at each end.


3. The second 2X4 is one that has one edge soaking in water. Shake off excess water and apply adhesive to the wet edge. Immediately place the sub flooring on the adhesive and nail at each end. Label this edge “Wet”.

4. Turn over and lay a bead of adhesive on the edge of the 2X4. Do not install sub flooring until 30 minutes has elapsed. Label that edge “30 Minutes”. After 30 minutes has elapsed the sub flooring can be installed and nailed at each end.

5. Store samples on bench for one week before testing.



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