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SBEIDCO – 1 st International Conference on Sustainable Built Environement Infrastructures in Developing Countries ENSET Oran (Algeria) - October 12-14, 2009 T. 4, [Durability of materials and structures], Use of waste glass as powder and aggregate in cement-based materials. R. Idir, M. Cyr, A. Tagnit-Hamou 109 USE OF WASTE GLASS AS POWDER AND AGGREGATE IN CEMENT-BASED MATERIALS R. Idir 1 , M. Cyr 2 , A. Tagnit-Hamou 3 T. 4. Durability of materials and structures ABSTRACT Demand for recycled
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  SBEIDCO  –   1 st  International Conference on Sustainable Built Environement Infrastructures in Developing CountriesENSET Oran (Algeria)-October12-14, 2009T.4,[Durability of materials and structures],Use of waste glass as powder and aggregate in cement-based materials.R. Idir,M. Cyr, A. Tagnit-Hamou 109 USE OF WASTE GLASS AS POWDER AND AGGREGATE INCEMENT-BASED MATERIALS R. Idir 1 , M. Cyr 2 , A. Tagnit-Hamou 3 T.4.Durability of materials and structures ABSTRACT Demand for recycled glass has considerably decreased in recent years, particularly for mixed-glass. Glass ischeaper to store than to recycle, as conditioners require expenses for the recycling process. There are severalalternatives for the reuse of composite-glass. According to previous studies, all these applications, which requirepre-conditioning and crushing, are more or less limited and unable to absorb all the quantities of waste glassavailable. In order to provide a sustainable solution to glass storage, a potential and incentive way would be toreuse this type of glass in concretes.Depending on the size of the glass particles used in concrete, two antagonistic behaviors can be observed: alkali-silica reaction, which involves negative effects, and pozzolanic reaction, improving the properties of concrete.The work undertaken here dealt with the use of fine particles of glass and glass aggregates in mortars, eitherseparately or combined. Two parameters based on standardized tests were studied: pozzolanic assessment bymechanical tests on mortar samples and alkali-reactive aggregate characteristics and fines inhibitor evaluationsby monitoring of dimensional changes. It is shown that there is no need to use glass in the form of fines since noswelling due to alkali-silica reaction is recorded when the diameter of the glass grainsis less than 1mm. Besides,fine glass powders having specific surface areas ranging from 180 to 540m² / kg reduce the expansions of mortarssubjected to alkali-silica reaction (especially when glass aggregates of diameters larger than 1 mm are used). KEYWORDS Waste-glass, glass aggregate, glass powder, alkali-silica reaction, pozzolanic reaction. 1 Université de Toulouse; UPS, INSA; LMDC (Laboratoire Matériaux et Durabilité des Constructions); 135,avenue de Rangueil; F-31 077 Toulouse Cedex 04, France,ridir@insa-toulouse.fr 2 Université de Toulouse; UPS, INSA; LMDC (Laboratoire Matériaux et Durabilité des Constructions); 135,avenue de Rangueil; F-31 077 Toulouse Cedex 04, France, cyr@insa-toulouse.fr 3 Département de génie civil, Université de Sherbrooke, Sherbrooke (Québec), Canada J1K 2R1,a.tagnit@USherbrooke.ca  SBEIDCO  –   1 st  International Conference on Sustainable Built Environement Infrastructures in Developing CountriesENSET Oran (Algeria)-October12-14, 2009T.4,[Durability of materials and structures],Use of waste glass as powder and aggregate in cement-based materials.R. Idir,M. Cyr, A. Tagnit-Hamou 110 1. INTRODUCTION Glass is a common product that can be found in different forms: bottles, jars, windows andwindshields, bulbs, cathode ray tubes, etc. Theseproducts have a limited lifetime and must berecycled in order to avoid environmental problems related to their stockpiling or landfilling. Severalrecycling channels already exist for glass recovery.This paper deals with the recycling of glass bottles,which can usually be reused after being crushedand melted.This operation is easily feasible when the glass is recovered as separate colors to produceglass products of the same color. However, most of the time, the collected glass is mixed and sounusable for the production of bottles of a given color. Consequently, this glass can either be reusedfor other but limited purposes, or be sent to a landfill.One of the possible channels for the recycling of mixed glass is cement-based materials, but most of existing studies recommend its use only as fine powders[Shayan& Xu2004] [Girbes et  al. 2004][Caijunet  al. 2005]. Fine particles of glass usually present pozzolanic activity beneficial to theconcrete, while coarse particles are usually deleterious toconcrete due to alkali-silica reaction (ASR).Although the use of fine particles is an effective solution for glass in concrete, the crushing of glassrepresents a significant cost since several hours of treatment are needed to obtain an efficient finenessof glass (almost equivalent to cement).The aim of this study is to recycle glass in cement-based materials by combining fine and coarse glassparticles, leading to a decrease in the crushing energy used. It is assumed that it is possible to takeadvantage of the beneficial activity of fine particles to counteract the deleterious effect of coarsegrains. 2.EXPERIMENTAL PROCEDURES2.1.Materials The glass used in this study was bottle soda-lime silica glass of mixed colors, coming from the Unicalgroup (Canada). It was composed of 40, 33, 20 and 1% of colorless, brown, green and blue glasses,respectively. The material also contained around 6% of impurities. The density was 2.5 g/cm 3 .Different sizes of glass particles were obtained after grading, washing, drying, crushing and sievingthe raw material. Tables 1 and 2 give the chemical composition and the fineness respectively of theclasses used in this study.The cement used was a Portland cement, CEM I 52.5R, according to EN 197-1 [NF EN 197-12001],having a Blaine specific surface area of 440 m 2  /kg. Its chemical composition is given in Table 1.The aggregate was a non-reactive marble sand having a density of 2.7 g/cm 3 . Four size classes wereprepared after crushing and sieving. The particle size distribution ranged from 160 to 2500 µm.Particles under 160 µm were rejected to avoid the interaction of fine non-reactive particles with fineglass particles. Table 3 gives the different classes used for this non-reactive marble. Table 1. Chemical composition of glass and cement (% by mass) SiO 2  Al 2 O 3  Fe 2 O 3  CaO MgO SO 3  Na 2 O K  2 O Loss on ignition Glass68.62.00.312.31.00.213.510.01.0Cement19.85.62.563.61.83.10.10.71.7  SBEIDCO  –   1 st  International Conference on Sustainable Built Environement Infrastructures in Developing CountriesENSET Oran (Algeria)-October12-14, 2009T.4,[Durability of materials and structures],Use of waste glass as powder and aggregate in cement-based materials.R. Idir,M. Cyr, A. Tagnit-Hamou 111 Table 2. Fineness of glass particles Glass classes C0 C1 C2 C3 C4 C5 C6 C7 C8  Mean diameters of particles (µm)37501875940472.5237.512010,810,87.8Specific surface area* (m 2  /kg)1.12.24.5111835182389538 * calculated from the average diameter of particles Table 3. Mean diameters of classes of marble non-reactive sand Classes of sand C1 C2 C3 C4 Mean diameters of particles (µm)1875940473238 2.2. Sample preparation and test methods All tests were carried out on mortars made of one part of cement and three parts of sand, by mass. Thewater-cement ratio was set to 0.6. Alkalis (KOH tablet) were added to the water to reach 5.6 kg/m 3 of Na2O eq  (including alkalis of the cement). Mortars were prepared according to standard EN 196-1.They were cast in 2x2x16 cm prisms and demolded 24 hours after casting. The prisms were thenstored at 60°C, after being placed on grids in watertight containers containing 20 mm of water (mortarbars were not in contact with the water). Expansion was measured using the scale micrometer method(specimens had shrinkage boltsat both ends). Each measurement was the mean of three values fromthree replicate specimens. Expansion measurements were performed after the containers and theprisms had been cooled for 24 hours at 20ºC.The first part of the study consisted in evaluating the swelling potential due to alkali-silica reaction of all size-classes of glass. So 20% of non-reactive sand was replaced in each mortar by glass of equivalent fineness. Grading curves were adapted when the tested glass class was out of the range of non-reactive sand (160-2500µm). In the second part of the study, the efficiency of fine glass particlesto counteract the ASR of coarser ones (C0 and C1) was tested, by using three classes of fines (C5, C6and C8) as 20 and 40% replacement of non-reactive sand. Tables 4 and 5 summarize the differentmortars tested in both series. 3. RESULTS3.1 The different classes of glass tested separately Results of expansion measurements on mortar prisms made with 20% of glass of different classes(replacement of non-reactive sand) are given in Figure 1. It can be seen that the particle size of theglass is a major parameter controlling the expansion values. A critical threshold of grain size around0.9-1mm was observed, under which no expansion occurred. Only coarse particle size classes (2.5-5mm and 1.25-2.5mm) led to significant expansion of mortar prisms. Particle sizes under thatthreshold had no effect on length variations. Some authors have already evoked the existence of acritical diameter causing abnormal expansion due to ASR.Jin et al. [2000], Xie et al. [2003] andByars et al.[2004] estimated this diameter to be between 0.60 and 1.18mm. However, other authorshave found lower values: between 0.15 and 0.30 for Yamada et al. [2005] and 0.038mm for Meyer etal. [1997].In the actual conditions of the test, glass particle sizes under 1mm were not deleterious in terms of alkali-silica reaction (ASR). In order to evaluate the consequences of this result on the mechanicalbehavior of the mortars, compressive strength tests were carried out on all mixtures.Figure 2 givesthe compressive strength results of mortars containing the different size classes of glass and cured inthe same conditions as for ASR tests. It can be seen that, compared to reference mortar without glass,the strengths were up to 10 MPa lower when alkali-reactive classes C0 and C1 were used.  SBEIDCO  –   1 st  International Conference on Sustainable Built Environement Infrastructures in Developing CountriesENSET Oran (Algeria)-October12-14, 2009T.4,[Durability of materials and structures],Use of waste glass as powder and aggregate in cement-based materials.R. Idir,M. Cyr, A. Tagnit-Hamou 112 Table 4. Mortars made to evaluate the swelling potential due to alkali-silica reaction of all size-classes of glass Table 5. Mortars made to evaluate the efficiency of fine glass particles to counteract ASR of coarserparticles C0 and C1NotationType and content of aggregateType and content offinesC0C1C5C6C8C0-20%C520%20%C0-40%C520%40%C0-20%C620%20%C0-40%C620%40%C0-20%C820%20%C0-40%C820%40%C1-20%C520%20%C1-40%C520%40%C1-20%C620%20%C1-40%C620%40%C1-20%C820%20%C1-40%C820%40%In contrast, fines of classes C3 to C8 systematically gave extra strength, which increased with thefineness of the glass particles. The most significant effects were obtained with fines of 80µm or less,the strength increases being of about 30-35 MPa for the finer particle sizes (C6, C7 and C8).This series of tests seemed to show that glass particles need to be crushed in order to use them withoutrisk of swelling. However, is it necessary to completely renounce the use of coarse glass particles inconcrete? Although coarse glass can potentially deteriorate concrete, its use presents at least twobenefits: a low crushing cost and an increase of the amount of glass that can be incorporated in theconcrete. For instance, assuming a typical concrete mix design containing 1800 kg/m 3  of aggregates, areplacement of 20% of aggregate by the glass leads to the use of 360 kg/m 3  of glass. So a secondseries of tests were carried out to test the efficiency of fine glass particles to counteract the ASR of coarser ones. 3.2. Fine and coarse classes of glass combined in the same mortars Figure 3 reports the expansion-time curves of mortars containing the combinations of C0 or C1 (20%of the aggregate) with one of the three classes of fines C5, C6 or C8 (20 or 40% replacement of non-reactive sand). It can be seen that the use of glass fines led to a reduction of expansion of mortars incomparison with mortars with coarse particles C0 or C1 alone. This reduction depended on thefineness of the glass (C5, C6 or C8) and the quantity of fines (20 or 40%). All three classes of finessystematically led to a decrease of the expansion provoked by C0 or C1, even for the class having thelowest fineness (C5). The general trend observed was that, the higher the particle finenesses, thelower the expansions of the mortars.Figure 4 shows that the efficiency of fines in reducing expansion was significantly improved when theamount of fines increased, whatever the coarse particle size used (C0 or C1). The reductions reached50 to 90% when 40% of fines were used, as against 25 to 70% for 20% of fines. 40% of fines C6 orC8 (i.e. particle size < 80µm) could lead to a reduction of 90%. Here, the effect of fineness was lesssignificant. Figure 5 highlights the general trend of the effect of fines in mortars: they reduced theexpansion and increased of strength of mortar prisms.Classes of glassC0C1C2C3C4C5C6C7C8Notation of mortarsM0M1M2M3M4M5M6M7M8Replacement of sand20%
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