Use of recycled alumina as fine aggregate replacement in self-compacting concrete Gritsada Sua-iam a , Natt Makul b,⇑ a Department of Building Technology, The Project for Consortium on Doctoral Program of Phranakhon Rajabhat University, 9 Changwattana Road, Bangkhen, Bangkok 10220, Thailand b Faculty of Industrial Technology, Phranakhon Rajabhat University, 9 Changwattana Road, Bangkhen, Bangkok 10220, Thailand highlights Alumina waste (AW) was recycled and reused in self-compacting concrete. Fine aggregate was replaced with up to 100% AW by weight. Workability of the SCC was satisfactory when AW was added at not more than 75 wt%. Addition of 75% AW improved the compressive strength. article info Article history: Received 4 January 2013 Received in revised form 23 March 2013 Accepted 4 May 2013 Keywords: Recycled alumina waste Fine aggregate Self-compacting concrete Rheology Mechanical properties abstract Alumina is a common by-product of industrial grit blasting operations. While alumina itself is relatively harmless, the grit blasting waste is regarded as hazardous when contaminated with heavy metals. The concrete industry has initiated the use of solid waste additives in order to address environmental problems. We studied the feasibility of using alumina waste (AW) as a partial replacement for the fine aggregate in self-compacting concrete (SCC). The mixtures were designed to produce a controlled slump flow diameter. The fine aggregate was replaced with up to 100% AW by weight. The rheological and mechanical properties of the SCC mixtures were evaluated based on slump flow, J-ring flow, blocking assessment, V-funnel, air content, compressive strength, and ultrasonic pulse velocity measurements. The filling and passing ability of the fresh concrete decreased in proportion to the alumina content. Mix- tures containing up to 75% AW possessed average compressive strengths of 20.9 MPa at 3 days and 45.9 MPa at 28 days. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction Abrasive blasting is a surface cleaning and preparation tech- nique used in many industries. The process involves the forceful direction of an abrasive medium against the surface of a workpiece. The abrasive may be applied either dry or suspended in a liquid. Abrasive blasting originated in 1904 and is currently used for sur- face cleaning and finishing, stress relief, etching, deburring, and flash removal [1]. Sandblasting waste is the residual material generated during the blasting process and contains the original abrasive material as well as any material that was removed from the target surface. Abrasive blasting is often used to remove paints and primers, and these materials frequently contain chemicals that pose a risk to hu- man health or to the environment. Recycling of the used media into other products may be an economically sound option for large producers of waste [2]. Recently, a number of researchers have studied the possibility of recycling abrasive blasting grit as an aggregate replacement in construction materials. Madany et al. [3] studied the use of copper-containing blasting grit waste as a replacement for marine sand in the manufacture of 15-cm concrete blocks and obtained an average compressive strength of 12 N/mm 2 , within the specifications for precast blocks. Leaching test results indicated that the encapsulated waste could be categorized as non-hazardous [4]. Heath et al. [5] examined the hazard potential of abrasive waste from a shipyard, given that many marine coat- ings include lead-based primers or copper and butyltin-containing antifouling topcoats. The most feasible application for the spent grit was as a partial fine aggregate replacement in asphaltic concrete. A test program was established that included character- ization, bench-scale testing, long-term pilot scale testing, and a full-scale demonstration. Full-scale production samples were used to demonstrate that both the chemical leaching resistance and 0950-0618/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.conbuildmat.2013.05.065 ⇑ Corresponding author. Tel./fax: +66 2 544 8000. E-mail address: [email protected](N. Makul). Construction and Building Materials 47 (2013) 701–710 Contents lists available at SciVerse ScienceDirect Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat
Transcript
Construction and Building Materials 47 (2013) 701–710
Contents lists available at SciVerse ScienceDirect
Gritsada Sua-iam a, Natt Makul b,⇑a Department of Building Technology, The Project for Consortium on Doctoral Program of Phranakhon Rajabhat University, 9 Changwattana Road, Bangkhen, Bangkok 10220, Thailandb Faculty of Industrial Technology, Phranakhon Rajabhat University, 9 Changwattana Road, Bangkhen, Bangkok 10220, Thailand
h i g h l i g h t s
� Alumina waste (AW) was recycled and reused in self-compacting concrete.� Fine aggregate was replaced with up to 100% AW by weight.� Workability of the SCC was satisfactory when AW was added at not more than 75 wt%.� Addition of 75% AW improved the compressive strength.
a r t i c l e i n f o
Article history:Received 4 January 2013Received in revised form 23 March 2013Accepted 4 May 2013
Alumina is a common by-product of industrial grit blasting operations. While alumina itself is relativelyharmless, the grit blasting waste is regarded as hazardous when contaminated with heavy metals. Theconcrete industry has initiated the use of solid waste additives in order to address environmentalproblems. We studied the feasibility of using alumina waste (AW) as a partial replacement for the fineaggregate in self-compacting concrete (SCC). The mixtures were designed to produce a controlled slumpflow diameter. The fine aggregate was replaced with up to 100% AW by weight. The rheological andmechanical properties of the SCC mixtures were evaluated based on slump flow, J-ring flow, blockingassessment, V-funnel, air content, compressive strength, and ultrasonic pulse velocity measurements.The filling and passing ability of the fresh concrete decreased in proportion to the alumina content. Mix-tures containing up to 75% AW possessed average compressive strengths of 20.9 MPa at 3 days and45.9 MPa at 28 days.
� 2013 Elsevier Ltd. All rights reserved.
1. Introduction
Abrasive blasting is a surface cleaning and preparation tech-nique used in many industries. The process involves the forcefuldirection of an abrasive medium against the surface of a workpiece.The abrasive may be applied either dry or suspended in a liquid.Abrasive blasting originated in 1904 and is currently used for sur-face cleaning and finishing, stress relief, etching, deburring, andflash removal [1].
Sandblasting waste is the residual material generated duringthe blasting process and contains the original abrasive materialas well as any material that was removed from the target surface.Abrasive blasting is often used to remove paints and primers, andthese materials frequently contain chemicals that pose a risk to hu-
man health or to the environment. Recycling of the used mediainto other products may be an economically sound option for largeproducers of waste [2]. Recently, a number of researchers havestudied the possibility of recycling abrasive blasting grit as anaggregate replacement in construction materials. Madany et al.[3] studied the use of copper-containing blasting grit waste as areplacement for marine sand in the manufacture of 15-cm concreteblocks and obtained an average compressive strength of 12 N/mm2,within the specifications for precast blocks. Leaching test resultsindicated that the encapsulated waste could be categorized asnon-hazardous [4]. Heath et al. [5] examined the hazard potentialof abrasive waste from a shipyard, given that many marine coat-ings include lead-based primers or copper and butyltin-containingantifouling topcoats. The most feasible application for the spentgrit was as a partial fine aggregate replacement in asphalticconcrete. A test program was established that included character-ization, bench-scale testing, long-term pilot scale testing, and afull-scale demonstration. Full-scale production samples were usedto demonstrate that both the chemical leaching resistance and
Physical propertiesLoss on Ignition (% by mass) 1.70 0.01Particle size distribution (D
[4,3] lm)23.32 47.64
Bulk density (kg/m3) 1550 1930Specific gravity 3.20 3.39Specific surface area (m2/kg) 610 321
a N/D indicates ‘‘Not Detected’’.b Potential air contaminants.
702 G. Sua-iam, N. Makul / Construction and Building Materials 47 (2013) 701–710
physical performance characteristics were acceptable. By usingrecycled grit waste in stabilized asphalt mixtures, the shipyardachieved an economic advantage by reducing the costs requiredfor collection, transport, and disposal [6].
The abrasive used in a particular application is usually specificto the blasting method. Because of its cost, longevity, and hard-ness the most widely used abrasive in sand blast finishing andsurface preparation is aluminum oxide. This material has a den-sity of 1.8 kg/L and a hardness of 8 on the original Mohs scale,and is second only to silicon carbide in sharpness [1]. Aluminais normally available in sizes ranging from 24- to 325-mesh [7].The cost of alumina dictates that it be utilized in enclosed blast-ing systems to filter and recover the abrasive, since because of itsangularity and durability it may be recycled many times. How-ever, the material must eventually be discarded as waste. Withrespect to its use in construction materials, alumina waste (AW)is characterized as a supplementary cementitious material. Elin-wa and Mbadike [8] studied the use of alumina waste for con-crete production using mixtures proportioned to produce acement content of 290 kg/m3 and a water–cement ratio of 0.40.They determined that the optimum cement replacement level interms of compressive and flexural strength was 10%. Arimanwaet al. [9] applied Scheffe’s simplex theory to develop a modelfor predicting the compressive strength for AW-containing con-crete. The compressive strengths predicted by this model agreedwith the corresponding experimentally obtained values, predict-ing an optimum compressive strength for AW-containing con-crete of 28.83 N/mm2 for mixtures with a water–cement ratioof 0.58 and an alumina content of 38%. The density of the result-ing concrete was not significantly affected by the addition of alu-mina waste, and both the initial and final setting times weredecreased. The AW absorbed water from the mix and thereforereduced workability, and mixtures containing large amounts ofalumina required higher water–cement ratio than straight ce-ment/sand mixes [10].
Self-compacting concrete (SCC) was introduced in 1988 in Japanto address a lack of skilled workers, and the material has sincegained wide acceptance in the construction industry. SCC is highlyflowable under its own weight and exhibits good segregation resis-tance, enabling it to fill voids and surround reinforcements withoutthe need for vibratory compaction during the placing process [11].SCCs typically have a higher fine particle content and improvedflow properties compared to conventional concrete. The self-com-patibility of the concrete mixture may be affected by the physicalcharacteristics of the constituents and the mixture proportions,which are intended to provide high flowability while maintaininga low water–cement ratio [12]. The aggregates have a significantinfluence on the rheological and mechanical properties of the con-crete. Their specific gravity, particle size distribution, shape, andsurface texture influence the properties of concrete in the freshstate [13]. Several papers have described the successful incorpora-tion of waste materials as partial replacements for fine aggregate inSCC. Ali and Al-Tersawy [14] studied the use of recycled glass andreported that the slump flow increased with increasing glass con-tent, but the mechanical properties of the mixture were inferior.Sua-iam and Makul [15] studied the feasibility of using limestonepowder (LS) as a modifying agent in self-compacting concrete inwhich a portion of the fine aggregate was replaced with untreatedrice husk ash (RHA). The fresh properties of the RHA-containingmixtures were improved in mixtures containing less than 60 vol%RHA. Addition of limestone powder improved concrete mixturescontaining untreated RHA.
In this work we report the use of alumina waste as a fine aggre-gate replacement material in self-compacting concrete and de-scribe the effects of alumina incorporation on the mechanicalproperties of the concrete.
2. Experimental program
2.1. Materials
All materials used in this study were obtained locally. The mixtures were pre-pared using Type 1 Portland cement (OPC) complying with ASTM C150 [16]. Alu-mina waste (AW) was obtained in the form of used abrasive blasting media froma turbine maintenance facility in Rayong Province, Thailand. The AW was incorpo-rated into the concrete mixtures without prior treatment. The material flow in thegrit blasting process is illustrated in Fig. 1.
The chemical compositions and physical properties of the cement and recycledalumina waste are listed in Table 1. Abrasive blasting can generate large quantitiesof dust containing high levels of toxic air contaminants including chromium, cobalt,nickel, and titanium. A summary of the potential health hazards associated withabrasive blasting air contaminants and their corresponding OSHA Permissible Expo-sure Limits (PELs) Department of Labor. Abrasive Blasting Hazards in ShipyardEmployment. Occupational Safety and Administration (OSHA) Guidance Document[17] are presented in Table 2.
The physical structure of AW and natural sand were examined using a scanningelectron microscope (SEM) operating at approximately 1000� magnification(Fig. 2). OPC, AW, and natural sand are crystalline materials (Fig. 3), with the majorphases being calcium silicate in OPC, corundum in AW, and quartz in natural sand.
A polycarboxylate-based high range water reducing admixture [HRWR] con-forming to ASTM C494 [18] standard type F was also added to the mixtures. The sol-ids content and specific gravity of the HRWR were 42% and 1.05. The HRWR wasadded in sufficient amounts to obtain a slump flow of 700 ± 25 mm.
Table 2The potential health hazards associated with abrasive blasting air contaminants [17].
Contaminant Potential health hazards OSHA PELs(mg/m3)
Aluminum Occupational overexposure to aluminum can lead to respiratory irritation 15 (total dust)5 (Respirabledust)
Chromium (III)(trivalent)
Occupational overexposure to trivalent chromium may lead to respiratory irritation and allergic dermatitis upon skin contact 0.5
Cobalt Occupational overexposure to cobalt can lead to chronic lung inflammation and pulmonary fibrosis, increase the risk of lungcancer, and cause allergic contact dermatitis with skin contact
0.1
Nickel Occupational overexposure to nickel compounds can increase the risk of lung and nasal cancers, and cause occupational asthmaand allergic dermatitis with skin contact
1
Titanium Occupational overexposure to titanium dioxide can lead to lung inflammation and pulmonary fibrosis 15
Fig. 2. SEM micrographs (1000�) of (a) Type 1 Portland cement (OPC), (b) alumina waste and (c) natural sand surface.
G. Sua-iam, N. Makul / Construction and Building Materials 47 (2013) 701–710 703
The particle size distributions of the Portland cement and recycled aluminawaste were measured using a Malvern Instruments Mastersizer 2000 particle sizeanalyzer. The Portland cement particles were slightly smaller than the AW particles(Fig. 4). The remainder of the fine aggregate was composed of natural sand of4.75 mm maximum size. The continuously-graded coarse aggregates used in thisstudy were composed of natural crushed stone of 20 mm maximum size. The prop-erties of the fine aggregate and coarse aggregate are presented in Table 3, and gra-dation of all aggregate materials conformed to the requirements of ASTM C33 [19](Fig. 5).
2.2. Mixture proportions
The compositions of the SCC mixtures are listed in Table 4. Mixtures were pre-pared containing various fine aggregate replacement amounts. The cement contentwas held constant at 450 or 550 kg/m3. The water content was adjusted to achievea w/c ratio of 0.38 or 0.45. Mass measurements were preferred to volume measure-ments due to the significant difference in specific gravity between AW and sand.AW was used to replace natural sand in amounts of 0%, 25%, 50%, 75, or 100% byweight.
2.3. Specimen testing
The slump flow diameter was maintained at 700 ± 25 mm.
1. The unit weight of the freshly-prepared SCC was measured as specified in ASTMC138 [20].
2. The air content was measured as specified in ASTM C231 [21].3. Slump flow tests were performed using an inverted mold without compaction
in accordance with ASTM C1611 [22]. The reported spread diameters are theaverages of four measurements.
4. The passing ability was tested using a J-ring according to the procedure in ASTMC1621 [23].
5. The filling ability was tested using a V-funnel according to the procedure out-lined in EFNARC [24].
6. The hardened properties were determined using ultrasonic pulse velocity andcompressive strength tests on triplicate cylindrical samples 150 mm in diame-ter and 300 mm tall after 3, 7, 14, 28 and 91 days in accordance with ASTMC597 [25] and ASTM C39 [26].
The acceptance criteria for the self-compacting concrete mixtures are describedin Table 5 [23,24].
0
100
200
300
400
500
600
10 15 20 25 30 35 40 45 50 55 60 65 70
0
200
400
600
800
1000
1200
1400
10 15 20 25 30 35 40 45 50 55 60 65 70
0
2000
4000
6000
8000
10000
12000
14000
10 15 20 25 30 35 40 45 50 55 60 65 70
Two – Theta (deg)
Inte
nsity
(ar
b un
it)In
tens
ity (
arb
unit)
C3SC2S
C3S
C3SC3S
C3S
C3S – 3CaO.SiO2
C2S – 2CaO.SiO2
Al2O3
Al2O3
Al2O3
Al2O3
Al2O3
Type 1 Portland cement
Alumina Waste
Two – Theta (deg)
Two – Theta (deg)
Inte
nsity
(ar
b un
it)
Natural sandSiO2
SiO2
SiO2
SiO2
SiO2
Fig. 3. X-ray diffraction spectra of OPC, AW and natural sand.
0
10
20
30
40
50
60
70
80
90
100
0.1 1 10 100 1000
OPC
Alumina waste
Cum
ulat
edfi
ner
(%)
D [4,3] = 47.64
D [4,3] = 23.35 µm
µm
Diameter ( m)µ
Fig. 4. Particle size distributions of natural sand, Type 1 Portland cement (OPC) andalumina waste.
704 G. Sua-iam, N. Makul / Construction and Building Materials 47 (2013) 701–710
3. Results
3.1. Properties of fresh alumina-containing SCC
The superplasticizer requirements, unit weight, T500 mm slumpflow, V-funnel, J-ring, blocking assessment, and air content test re-sults for the SCC mixtures are listed in Table 6.
0
10
20
30
40
50
60
70
80
90
100
0.1 1 10 100
Upper Gradation
Fine Aggregate
Coarse Aggregate
Lower Gradation
Pass
ing
(%)
Diameter size ( m)µ
Fig. 5. Gradation of fine aggregate and coarse aggregate.
slumps of 700 ± 25 mm diameter are plotted in Fig. 6. In order tomaintain the desired slump flow, mixtures containing aluminawaste required larger amounts of superplasticizer with increasingamounts of AW due to the smaller size and greater surface area ofthe alumina particles [10]. With higher cement content and water–cement ratio, the superplasticizer requirement was significantlydecreased. One reason for the reduced superplasticizer demandmay be the neutralization of AW particles by oppositely chargedfine aggregate particles, reducing flocculation. In addition, the ce-ment particles are effectively dispersed and can trap large amountsof water to provide satisfactory flow [27].
3.1.2. Unit weightThe unit weight of the SCC increased with increasing AW
replacement and decreased with increasing cement content. Thehigher unit weight of AW-containing mixtures was due to thegreater density of the AW particles and a filler effect caused bythe finer particle size.
3.1.3. T500 mm slump flowThe slump flow is reported as the mean diameter achieved by
the concrete mass after lifting the inverted slump mold. The slumpflow time is the amount of time required for the mixture to reach adiameter of 500 mm. All SCC mixtures exhibited acceptable flowtimes between 3 and 7 s, as specified in the EFNARC [24] guidelines(Table 5). All of the mixtures also exhibited satisfactory averageslump flows of 700 ± 25 mm diameter (Fig. 7), which is an indica-tion of good workability. The slump flow time increased withincreasing AW content to 75%, then decreased in mixtures contain-ing 100% AW. The flow time increased due to the increase in thequantity of water absorbed by the AW, which increased the viscos-ity of the paste and reduced the workability [9]. The decrease inflow time in the 100% AW mixture was due to the absence of aninterlocking effect in the AW particles, which also resulted in anunstable mortar mixture.
Table 6Properties of fresh SCC mixtures.
Mix Slump flow J-ring test V-funnel time (s) HRWR (%) Air content (%)
Fig. 6. Required superplasticizer dosage for SCC mixtures.
Fig. 7. Slump flow times for SCC mixtures.
706 G. Sua-iam, N. Makul / Construction and Building Materials 47 (2013) 701–710
3.1.4. V-funnel testThe V-funnel test determines the time required for a concrete
mixture to flow through a funnel and provides a means of evaluat-ing the viscosity and segregation resistance of concrete mixtures. AV-funnel flow time in the range of 8–12 s is considered acceptable
according to EFNARC [24] guidelines (Table 5). The flow time in-creased in proportion to the water requirement and level of aggre-gate replacement.
In mixtures 2, 3, 8, 13, 14, and 19 (Fig. 8), the V-funnel valueswere within the acceptable range, as the AW particles absorbedsufficient water to produce a highly viscous mix and reduce bleed-ing effects. Flow times could not be measured for the 100% mix-ture, and it appears that mixtures containing 50–75% AWrepresent the ideal composition in terms of V-funnelmeasurements.
3.1.5. J-ring test and blocking assessmentThe J-ring and slump flow tests provide a means of determining
the passing ability of SCC, or the ability of the concrete to flow un-der its own weight to completely fill all voids. The differences inthe slump flow and J-ring flow diameters were used to assign ablocking assessment (Table 5) according to the criteria defined inASTM C1621 [23], in which 0–25 mm is defined as no visible block-ing, 25–50 mm is defined as minimal to noticeable blocking, andgreater than 50 mm is defined as noticeable to extreme blocking.Samples containing greater amounts of cement exhibited minimalor no apparent blocking, while extreme blocking was observed in
Fig. 8. V-funnel flow times for SCC mixtures.
G. Sua-iam, N. Makul / Construction and Building Materials 47 (2013) 701–710 707
samples with low cement content. In J-ring tests, mixtures contain-ing AW achieved adequate passing ability and maintained suffi-cient resistance to segregation around congested reinforcementareas due to the combined influence of increased cement content,decreased water-cement ratio, and increased viscosity [11].
3.2. Properties of hardened SCC
The compressive strength and ultrasonic pulse velocity of theSCC samples were tested at 3, 7, 14, 28, and 91 days. The reportedvalues are the means of tests on three samples.
3.2.1. Compressive strengthThe average compressive strengths of the SCC samples are pre-
sented in Table 7. The compressive strength continued to increaseover the 91-day curing period. The 28-day compressive strengthranged from 22.9 to 59.9 MPa, while the 91-day compressivestrength ranged from 28.6 to 66.6 MPa. The greatest compressivestrength at 28 and 91 days was achieved in the high-cement, loww/c ratio mixture containing 75% AW. Conversely, the lowest com-pressive strength at all ages occurred in samples containing 0% AW.The increase in strength was ascribed to the filling ability and poz-
Table 7Compressive strength of SCC mixtures.
Mix no. Compressive strength (MPa), coefficient of variation (CV), (% control m
zolanic activity of AW [8,9]. The added alumina may be amorphousor glassy and reacts with calcium hydroxide produced from thehydration of calcium aluminates. The rate of the pozzolanic reac-tion is proportional to the amount of surface area available forreaction [28]. The mechanical interlocking capacity between thefine aggregate particles and the matrix phase, which improvesthe mechanical performance of the transition zone, is related tothe compressive strength. Both of these properties improve themicrostructure in the bulk paste matrix and transition zone [29].The compressive strength of concrete increases with curing time[8]. Moreover, the binding mechanisms of radionuclides to cementeventually enter calcium–silicate–hydrate (C–S–H) [30]. On theother hand, mixtures containing 100% AW possessed lower com-pressive strengths due to the lack of interlocking between theAW particles indicated by longer V-funnel flow times. In addition,residual impurities on the AW surface interfered with the bond be-tween the cement paste and the alumina waste [31].
3.2.2. Ultrasonic pulse velocityUltrasonic pulse velocity testing is used to evaluate the quality
of concrete. The velocity of ultrasonic pulses traveling in a solid
708 G. Sua-iam, N. Makul / Construction and Building Materials 47 (2013) 701–710
depends on the density and elastic properties of the material, andthe UPV is generally proportional to compressive strength [15].
The average ultrasonic pulse velocities of the hardened concretespecimens at 3, 7, 14, 28, and 91 days are listed in Table 8. Thevelocity ranged from 3.12 to 3.95 km/s at 28 days, while at 91 daysthe velocity ranged from 3.48 to 4.34 km/s. The variations corre-spond to the degree of densification within the internal structureof the SCC mixtures, and higher velocities generally indicate betterquality concrete in term of density, homogeneity, and lack ofimperfections [32]. The highest pulse velocities were achieved insamples containing 75% AW with a high cement content and loww/c ratio. Conversely, the lowest velocities at all ages occurred inthe control samples. Addition of AW increased the ultrasonic pulsevelocity in SCC samples at 3, 7, 14, 28 and 91 days, mostly due tofilling and pozzolanic effects on the physical and chemical proper-ties of the concrete [10]. Also, greater incorporation of aluminawaste may improve the compactness of the concrete granular skel-eton. Because the AW particles are finer than the standard sandaggregate, they fill the interstices between the coarse aggregatesmore completely, reducing the pore volume in the concrete[10,14,28,33].
4. Discussion
To maintain workability and keep the water–cement ratio low,a superplasticizer was employed. Increasing the amount of alu-
Fig. 9. Relationship between compressive strength and superplasticizer dosage ofdifferent contents of cement.
mina waste increased the required superplasticizer dosage. The ef-fect of cement content, at the same compressive strength toachieve satisfactory relative of low superplasticizer dosage withhigher cement and lower alumina content. On the other hand,the high superplasticizer dosage with lower cement and higheralumina content as shown in Figs. 9 and 10. The increasing ofsuperplasticizer dosage was increasing the compressive strength.The fine aggregate generally replacement with AW, thereforestrength tends to be governed as much by the cement content450 kg/m3 at a correlation is 0.8706, the cement content550 kg/m3 at a correlation is 0.8367 and the overall different con-tents of alumina at a correlation is 0.6622.
In order to meet the target physical properties, self-compactingconcrete containing high volumes of recycled alumina requiredlarge amounts of water, mainly because of the small size and in-creased surface area of the alumina waste. The mixture propor-tions were formulated to provide a high degree of flowabilitywhile maintaining a low water–cement ratio. In order to maintaindeformability along with flowability in the SCC, a superplasticizeris considered indispensable to reduce the water–cement ratiowithout a concomitant decrease in viscosity [12]. The relationshipbetween the V-funnel flow time and the 500 mm slump flow timeis depicted in Fig. 11. Mixtures 2, 3, 8, 13, 14, and 19 were withinthe range of acceptance criteria specified in the EFNARC guidelinesto maintain workability (8–12 s for V-funnel flow time and 3–7 sfor 500 mm slump flow time) [24]. The workability of SCC depends
Fig. 10. Relationship between compressive strength and superplasticizer dosage ofdifferent contents of alumina.
Fig. 11. Relationship between V-funnel flow time and 500 mm slump flow time.
y = 0.7208x3.1529
R² = 0.9102
0
10
20
30
40
50
60
70
80
2.0 2.5 3.0 3.5 4.0 4.5 5.0
w/c 0.38 w/c 0.45
Ultrasonic pulse velocity (km/s)
Com
pres
sive
str
engt
h (M
Pa)
Fig. 12. Relationship between compressive strength and ultrasonic pulse velocity ofw/c 0.38 and w/c 0.45 mixtures.
y = 0.6791x3.1673
R² = 0.8843
y = 1.2246x2.6652
R² = 0.9093
y = 1.1783x2.7685
R² = 0.9451
y = 0.9856x2.9493
R² = 0.948
y = 1.3663x2.6877
R² = 0.969
10
20
30
40
50
60
70
80
2.0 2.5 3.0 3.5 4.0 4.5
AW0% AW25% AW50% AW75% AW100%
Ultrasonic pulse velocity (km/s)
Com
pres
sive
str
engt
h (M
Pa)
Fig. 13. Relationship between compressive strength and ultrasonic pulse velocity ofdifferent contents of alumina.
G. Sua-iam, N. Makul / Construction and Building Materials 47 (2013) 701–710 709
on the cement content and water–cement ratio. For a water–cement ratio of 0.38 the maximum AW replacement level in whichthe acceptance criteria were met was 50% for a cement content of450 kg/m3 and 75% for a cement content of 550 kg/m3. Due to theincreased cement content indicated that low water–cement ratioin the mixtures, when concrete is deformed paste with a highviscosity also prevents localized increases in internal stress dueto the approach coarse aggregate particles [11]. Mixtures contain-ing large amounts of alumina waste exhibited decreased workabil-ity, as the AW-induced increase in binder surface area wassubstantial. The increased surface area adsorbed a greater amountof water, thus decreasing the quantity of free water available in themixture. The high heat of hydration generated by the presence ofthe alumina waste increased the drying rate [9]. Chromium ions,which may be present as impurities from the blasting process,are known to increase the rate of heat liberation early in the hydra-tion process [30].
With suitable amounts of alumina waste, the compressivestrength and ultrasonic pulse velocity increased, mostly due to in-creased filling ability and pozzolanic activity. In properly madeconcrete, each particle of aggregate and all of the spaces betweenthe aggregate solids is completely filled with paste, and the pastehas adequate binding strength [34]. The pozzolanic activity is re-lated to the total percentage of SiO2, Al2O3, and Fe2O3, which is90.12%, greater than the minimum (70%) specified in ASTM C618[35]. The major constituent of a pozzolan is amorphous or glassyalumina. This material reacts with calcium hydroxide produced
during the hydration of calcium aluminates. The rate of the pozzo-lanic reaction is proportional to the amount of surface area avail-able for reaction [28]. According to Evans [30], the Al3+ ionspresent in cement eventually enter the C–S–H phase by joiningwith a proton to replace a Si atom or by joining with anotherAl3+ ion to replace 3 Ca2+ ions. In addition, C–S–H may incorporatechromium through Si substitution in weakly crystalline structures.Cobalt was also strongly adsorbed on C–S–H gels, increasing thehydration time, and nickel has also been found highly adsorbedonto hydroxides, probably through co-precipitation or surfacecomplexation. Chemically improving the microstructure of thebulk paste matrix and transition zone leads to increased compres-sive strength. The correlation between the compressive strengthand the ultrasonic pulse velocity of different water–cement ratioand content of alumina as shown in Figs. 12 and 13, the mixtureswith a water–cement ratio of 0.38 was 0.9552, the mixtures witha water–cement ratio of 0.45 mixtures was 0.9102, while the mix-tures with a content of alumina 0%, 25%, 50%, 75% and 100% was0.8843, 0.9093, 0.9451, 0.969 and 0.948 respectively.
The pollutants and wastes typically generated by abrasive blast-ing include particulate air emissions and large quantities of spentabrasive. These wastes may be hazardous if the process involvesblasting operations on substrates or coatings containing toxic met-als. New technologies in the abrasive blasting industry that aid inreducing pollution and the amount of solid waste generated re-quire large capital investments. Recycling of the alumina wasteinto other products is also a viable option for waste reduction
710 G. Sua-iam, N. Makul / Construction and Building Materials 47 (2013) 701–710
and is sometimes an economically sound option for large wasteproducers. The use of spent alumina grit as an aggregate in the con-crete industry is a favorable recycling alternative [2]. It is believedthat toxic elements contained in the waste are effectively fixed inthe solid concrete matrix [34]. Use of alumina waste as a fineaggregate can reduce the cost of waste disposal and aggregatecosts, although addition of waste to aggregates should be approvedby local environmental protection authorities [17].
5. Conclusions
Based on our investigation of fine aggregate replacement withalumina waste under conditions of controlled slump flow, the fol-lowing conclusions were drawn:
1. To maintain constant flowability, inclusion of AW required anincrease in the amount of superplasticizer added. Highercement content and water–binder ratios decreased the neces-sary amount of superplasticizer.
2. All mixtures exhibited acceptable performance in slump flowdiameter and time tests. Flow times for mixtures containingup to 75% AW were increased, while flow times were decreasedin mixtures containing 100% AW.
3. There was some segregation in V-funnel tests and an increase inblocking in J-ring tests. AW mixes containing higher cementcontents (550 kg/m3) had substantially lower V-funnel flowtimes and minimal blocking, while increased alumina contenttended to increase V-funnel flow times and blocking.
4. The compressive strength decreased at higher water–cementratio and increased with increasing AW content up to 75%. Mix-tures containing up to 75% AW exhibited average increases incompressive strength over the control concrete of 180% at3 days and 165% at 28 days. When added in suitable propor-tions, AW increased early-stage and long-term compressivestrength due to filling effects and pozzolanic reactions.
References
[1] US Department of Health, Education and Welfare. Abrasive BlastingOperations. Final Report. Contract No. 210-75-0029, March 1976.
[2] Carlson JRJ, Townsend TG. Management of solid waste from abrasive blasting.Pract Period Hazard Toxic Radioact Waste Manage 1998;2(2):72–7.
[3] Madany IM, Al-Sayed MH, Raveendran E. Utilization of copper blasting gritwaste as a construction material. Waste Manage 1991;11:35–40.
[4] Madany IM, Raveendran E. Leachability of heavy metals from copper blastinggrit waste. Waste Manage Res 1992;10:87–91.
[5] Heath JC, Nelson B, Powell R, Means JL. Recycling spent sandblasting grit andsimilar wastes as aggregate in asphaltic concrete. Naval Facilities EngineeringService Center, December; 1998.
[6] Buruiana DL, Bordei M, Diaconescu I, Ciurea A. Recycling options for usedsandblasting grit into road construction. Recent Res Energy Environ LandscArchit. November; 2011.
[7] US Environmental Protection Agency. Abrasive Blasting. Emission FactorDocumentation for AP-42: Final, Report, September 1997.
[8] Elinwa AU, Mbadike E. The use of aluminum waste for concrete production. JAsian Archit Build Eng 2011:217–20.
[9] Arimanwa JI, Onwuka DO, Arimanwa MC, Onwuka US. Prediction of thecompressive strength of aluminum waste–cement concrete using Scheffe’stheory. J Mater Civ Eng 2012;24(2):177–83.
[10] Puertas F, Blanco-Varela MT, Vazquez T. Behaviour of cement mortarscontaining an industrial waste from aluminium refining stability in Ca(OH)2
solutions. Cem Concr Res 1999;29:1673–80.[11] Okamura H, Ouchi M. Self-compacting concrete. J Adv Concr Technol
2003;1(1):5–15.[12] Naik TR, Kumar R, Ramme BW, Canpolat F. Development of high-strength,
economical self-consolidating concrete. Constr Build Mater 2012;30:463–9.[13] Neville AM. Properties of concrete. 4th ed. New York: John Wiley & Sons Inc.;
1996.[14] Ali EE, Al-Tersawy SH. Recycled glass as partial replacement for fine aggregate
in self compacting concrete. Constr Build Mater 2012;35:785–91.[15] Sua-iam G, Makul N. Utilization of limestone powder to improve the
properties of self-compacting concrete incorporating high volumes ofuntreated rice husk ash as fine aggregate. Constr Build Mater 2013;38:455–64.
[16] ASTM C150 Standard specification for Portland cement. Annual book of ASTMstandards, vol. 04.01. Philadelphia, USA: American Society for Testing andMaterials; 2009.
[17] US Department of Labor. Abrasive Blasting Hazards in Shipyard Employment.Occupational Safety and Health Administration (OSHA) Guidance Document,December 2006.
[18] ASTM C494 Standard specification for chemical admixtures for concrete.Annual book of ASTM standards, vol. 04.02. Philadelphia, USA: AmericanSociety for Testing and Materials; 2011.
[19] ASTM C33 Standard specification for concrete aggregates. Annual book ofASTM standards, vol. 04.02. Philadelphia, USA: American Society for Testingand Materials; 2011.
[20] ASTM C138 Standard Test Method for Density (‘‘Unit Weight’’), Yield, and AirContent (Gravimetric) of Concrete. Annual book of ASTM standards, vol. 04.02.Philadelphia, USA: American Society for Testing and Materials; 2011.
[21] ASTM C231 Standard test method for air content of freshly mixed concrete bythe pressure method. Annual book of ASTM standards, vol. 04.02. Philadelphia,USA: American Society for Testing and Materials; 2011.
[22] ASTM C1611 Standard test method for slump flow of self-consolidatingconcrete. Annual book of ASTM standards, vol. 04.02. Philadelphia, USA:American Society for Testing and Materials; 2011.
[23] ASTM C1621 Standard test method for passing ability of self-consolidatingconcrete by j-ring. Annual book of ASTM standards, vol. 04.02. Philadelphia,USA: American Society for Testing and Materials; 2011.
[24] EFNARC. Specifications and guidelines for self-compacting concrete. February;2002.
[25] ASTM C597 Standard test method for pulse velocity through concrete. Annualbook of ASTM standards, vol. 04.02. Philadelphia, USA: American Society forTesting and Materials; 2011.
[26] ASTM C39 Standard test method for compressive strength of cylindricalconcrete specimens. Annual book of ASTM standards, vol. 04.02. Philadelphia,USA: American Society for Testing and Materials; 2011.
[27] Metha PK. High-performance, high-volume fly ash concrete for sustainabledevelopment. In: Proc Int Workshop Sustain Dev Concr Technol. Beijing,China; 2004. p. 3–14.
[28] Nazari A, Riahi S, Riahi S, Shamekhi SF, Khademno A. Influence of Al2O3
nanoparticles on the compressive strength and workability of blendedconcrete J. Am Sci 2010;6(5):6–9.
[29] Felekoglu B. Effects of PSD and surface morphology of micro-aggregates onadmixture requirement and mechanical performance of micro-concrete. CemConcr Compos 2007;29(6):481–9.
[30] Evans NDM. Binding mechanisms of radionuclides to cement. Cem Concr Res2008;2008(38):543–53.
[31] Somna R, Jaturapitakkul C, Rattanachu P, Chalee W. Effect of ground bagasseash on mechanical and durability properties of recycled aggregate concrete.Mater Des 2012;36:597–603.
[32] Singh G, Siddique R. Effect of waste foundry sand (WFS) as partial replacementof sand on the strength, ultrasonic pulse velocity and permeability of concrete.Constr Build Mater 2012;26(1):416–22.
[33] Yot PG, Méar FO. Characterization of lead, barium and strontium leachabilityfrom foam glasses elaborated using waste cathode ray-tube glasses. J HazardMater 2011;185(1):236–41.
[34] Benson RE, Chandler HW, Chacey KA. Hazardous waste disposal as concreteadmixture. J Environ Eng 1985;111(4):441–7.
[35] ASTM C618 Standard Specification for Coal Fly Ash and Raw or CalcinedNatural Pozzolan for Use in Concrete. Annual book of ASTM standards, vol.04.02. Philadelphia, USA: American Society for Testing and Materials; 2011.
