Concrete Mix Design IS 10262:2009

A K GUPTA EXECUTIVE ENGINEER (TRAINING)

14/02/2017

Introduction

• Concrete Mix Design means, determination of the proportion of the concrete ingredients i.e. Cement, Water, Fine Aggregate, Coarse Aggregate which would produce concrete possessing specified properties such as workability, strength and durability with maximum overall economy.

Types of Concrete Mixes1. Nominal Mixes – • These mixes are of fixed cement-aggregate ratio. • These offer simplicity and under normal circumstances.• Have a margin of strength above that specified.2. Standard Mixes – • The minimum compressive strength has been included

by IS-456:2000 in many specifications. These mixes are termed standard mixes.

• E.g.: M10, M15, M20, etc.3. Designed Mixes -• In these mixes the performance of the concrete is

specified by the designer but the mix proportions are determined by the producer of concrete, except that the minimum cement content can be laid down.

Methods of Concrete Mix Design

• American Concrete Institute Method (ACI Method)

• Road Note Number 4 Method• DOE Method• Indian Standard Method (IS Method)

Mix Design (IS 10262 - 2009)

DATA REQUIRED

Step1 Target Mean Strength

Standard Deviation

• Number of test results of samples taken from site-30

• Standard deviation for each batch if significant changes in concrete batches

• Standard deviation to be brought upto date.

Asuumed Standard Deviation

Assumptions in Standard deviation

Selection of Mix Proportion Clause 4.1

• Selection of Water cement ratio• For the same water cement ratio ,the compressive

strength may differ according to different cement, supplementary cemetitious materials, aggregate size, grading, shape and surface texure.

• Preliminary w/c may be selected from established relationship between w/c ratio and compressive strength.

• Alternatively w/c ratio may be selected from table 5 of IS: 456 for respective exposure condition.

Selection of w/c ratio

Workability (Clause 7.1, IS:456-2000)

Degree of Site Control(Table 8, IS:456-2000)

Type of Exposure (Table 3, IS:456-2000)

Step2 Selection of water/cement ratio

Step2 Selection of water/cement ratioBut from table – 5, IS-456:2000

Step2 Selection of water/cement ratio

Considering moderate exposure, Max w/c = 0.5 Hence w/c = 0.38

w/c = 0.38

4.2 Selection of Water content

Water content is influenced by……..• Aggregate size• Shape• Texture• Workability• w/c ratio• Other supplementary cementitious material• Admixture• Environment conditions

4.2 Selection of Water content

Selection of water content

Water content in table -2 is for• Angular coarse aggregate , • - 10 kg for sub angular aggregate• -20 kg for gravel with some crushed particles.• -25kg for rounded gravel• Slump-25to 50mm, increase by 3 % for every

additional slump of 25mm.

Water content for admixtures

• -5 to -10% for water reducing admixtures • -20% for superplasticisers.

Water reducers

• At constant workability – The reduction in mixing water is expected to be

of the order of 5% to 15%.Naturally increases the strength.• At constant w/c ratio –Increased workability.Slump of 30mm to 150 mm.

Water reducers

1.Thin walls of water retaining structures with high percentage of steel reinforcement

2.Deep beams, column and beam junctions3.Tremie concreting4.Pumping of concrete5.Hot weather concreting6.Concrete to be conveyed for considerable

distance and in ready mixed concrete industries

Super Plasticisers

Superplasticizers constitute a relatively new category and improved version of plasticizer, the use of which was developed in Japan and Germany during 1960 and 1970 respectively. They are chemically different from normal plasticisers.Classification of Superplasticizers:Sulphonated malanie-formaldehyde condensates (SMF)Sulphonated naphthalene-formaldehyde condensates (SNF)Modified lignosulphonates (MLS)Other types

SuperplasticisersPermits reduction of water content about

30% without reducing the workabilityIt is possible to use w/c ratio as low as 0.25 or

even lower and yet to make flowing concrete to obtain strength of order 120 Mpa or more.• Production of high strength and high

performance concrete• Production of flowing, self levelling, self

compacting concrete

Step3 Selection Of Water Content.• From table – 2, IS-10262:2009 (For 20mm nominal max. size of aggregate & 25 to

50mm slump) Max WC = 186 kg/m3

# Correction for slump in water content (according to clause 4.2, IS:10262)

Slump = 100 mm Correct WC for 100 mm slump = 186 + 6%

= 197.16 kg 197 kg of water per m3 of concrete

4.3 Calculation of cementitious Material content

• Calculate cementitious material from the water cement ratio and the quantity of water per cum(water content)

• Check it from durability requirement .• Select higher value • The maximum as per IS 456

Step4 Calculation Of Cement Content

Other Cementitious materials

Fly ash

Blast Furnace Slag

Silica Fume

Nano Silica fume

Rice Husk ash

Metakaoline

Surkhi

4.4 Estimation of coarse aggregate proportion

Coarse aggregate proportions

• Table -3 is for water cement ratio of 0.5, proportion may be suitably adjusted for other water cement ratio.(@-or+.01 for every change in water cement ratio of .05)

• For given workability ,the volume of coarse aggregate depends upon its nominal max size and grading zone of fine aggregate.

• Reduce the estimated CA content by 10% if pumping is to be done. It should be consistent with IS 456 and meet project specifications.

4.5Combination of Different Coarse Aggregate Fractions

4.6 Estimation of Fine aggregate Proportion

• Find out the absolute volume of cementitious material, water and chemical admixture by dividing their masses by their respective specific gravity and multiplying by 1/1000.

• Subtract the result of summation above from unit volume. Find volume of total aggregates

• Divide coarse and fine aggregate fractions by volume as per clause 4.4.

• Find CA and FA by multiplying their volumes with respective specific gravities and multyplying by 1000.

Step 5: Selection of Proposition of Volume of Coarse Aggregate

From table 3,(IS-10262:2009) for zone IIIrd of F.A. Maximum size of aggregate = 20 mm. Vol. of CA per unit vol. of total aggregate = 0.64# For 0.1 decrease in w/c & increase in CA by 0.02 Applying correction of 0.024 Vol. of CA = 0.64 + 0.024 =0.664m3

Total aggregate = 1 CA = 0.664m3

FA = 0.336m3

Quantities by volume

• Cement—518.42/(3.15*1000)=.165 cum• Water ----197/(1*1000)=.197cum• Aggregates -----1-(.165+.197)=.638 cum• CA-------------.638*.664=.4236cum• FA----------------.638*.336=.214 cum

Quantities by Mass

• Cement-----518.42 kg• Water ----------197 kg• CA--------------.4236*2.74*1000=1161.76kg• FA------------.214*2.74*1000=586.36 kg

Step6 Mix Calculation Results:

Mass of Cement

Water F.A. C.A.

518.42 197 586.36 1161.76

1 0.38 1.13 2.24

Ratio Obtained

1 : 1.13 : 2.24

Trial Mixes

• Check the workability of trail mix-1. Free from segregation and bleeding .See finishing properties;

• If not satisfactory . Trial mix-2 with varying water and admixture keeping pre-selected value of water cement ratio.

• Trial mix 3 and 4 with same water content as that of mix-2 but varying water cement ratio.

• Find relationship between compressive strength and w/c ratio.

• Field trails

Thanks For

Hearing