Effects of windshield waste glass on the properties of structural repair mortars

The use of waste glass incorporated into construction materials has been the focus of several studies. Its utilization in cementitious matrices as a cement surrogate has been the most suitable application because of its potential pozzolanic properties. In this study, the influence of varying the amount of cement replaced by waste glass on several mechanical properties considered essential to ensuring the performance of mortars in structural repair, such as compressive strength, modulus of elasticity, linear shrinkage and tensile bond strength, was analyzed. Additionally, the influence of waste glass on water absorption by capillarity and the microstructure of these mortars were also assessed. The results indicate the potential use of this waste material for cement mortars. The 5% replacement rate showed the best results.     

火山灰活性评价方法及其影响因素

介绍了国内外水泥混凝土中使用的火山灰质材料活性评价方法的分类和研究现状,并分析了影响火山灰活性的因素,如细度、化学成分、矿物成分和热处理温度等。火山灰活性评价方法主要有酸碱溶出法、石灰吸收法、热分析法等直接测量火山灰活性的方法和强度指数法、电导率法、水化热反应热法等间接测量火山灰活性的方法。通过分析各种影响火山灰活性的因素,得出以下结论:火山灰质材料越细或比表面积越大,火山灰活性越高;火山灰质材料中非晶态硅酸盐和铝酸盐含量越高,则火山灰活性越高;适当的热处理温度将有效提高一些火山灰质材料的火山灰活性。     

Comparison of ground waste glass with other supplementary cementitious materials

Finely ground glass has pozzolanic properties that make attractive its recycling as supplementary cementitious material. This paper compares the behaviour of waste glass powders of different fineness with that of natural pozzolana, coal fly ash and silica fume. Chemical analysis, compressive strength measurements and durability tests were carried out to investigate the effect of ground glass on strength and durability performances of mortars. Blended both with Portland cement and lime, ground glass improved strength, resistance to chloride penetration and resistance to sulphate attack of mortars more than natural pozzolana and similarly to fly ash. Mortars with ground glass immersed in water for seven years did not show any sign of degradation and increased their compressive strength. The ranking of ground glass with respect to the other mineral additions was not affected by fineness.     

Properties of high volume glass powder concrete

Mechanical and durability properties of concrete with cement replaced by finely grounded glass powder in high volume up to 60% were investigated. XRD and TGA analyses indicated that the fine glass powder reacted with calcium hydroxide to form calcium-silicate-hydrates. As such, the microstructures of concrete were more compact and homogeneous, especially at the interfacial transition zone. Concrete with cement replaced by 15% and 30% glass powder exhibited the highest strength increase and correspondingly the lowest porosity. Beyond a replacement of 30%, calcium hydroxide became insufficient for the pozzolanic reaction of glass powder. However, the high volume glass powder concrete retained distinct resistance against water and chloride ingress, due to the reduction in pore size and connectively. Reductions of 77%, 83%, 96%, 91% and 92% were observed respectively for water penetration depth, sorptivity, conductivity, chloride diffusion and migration coefficients in concrete with cement replaced by glass powder by 60%.     

Evaluation of bagasse ash as supplementary cementitious material

The utilization of waste materials in concrete manufacture provides a satisfactory solution to some of the environmental concerns and problems associated with waste management. Agro wastes such as rice husk ash, wheat straw ash, hazel nutshell and sugarcane bagasse ash are used as pozzolanic materials for the development of blended cements. Few studies have been reported on the use of bagasse ash (BA) as partial cement replacement material in respect of cement mortars. In this study, the effects of BA content as partial replacement of cement on physical and mechanical properties of hardened concrete are reported. The properties of concrete investigated include compressive strength, splitting tensile strength, water absorption, permeability characteristics, chloride diffusion and resistance to chloride ion penetration. The test results indicate that BA is an effective mineral admixture, with 20% as optimal replacement ratio of cement.     

Effects of particle size of treated CRT funnel glass on properties of cement mortar

Over the last decade, new types of display technologies have increasingly replaced cathode ray tube (CRT) displays leading to an increase in the disposal of discarded old CRT monitors and TV sets. The present study is a further development of our previous work to explore the effects of using different size fractions of crushed CRT glass as 100 % substitution of sand in cement mortar. A range of cement mortar mixes were prepared and the tests conducted included table flow (fluidity), mechanical strength, drying shrinkage, alkali–silica reaction (ASR) expansion and toxicity characteristic leaching procedures. Generally, the results obtained for the CRT glass-based cement mortars were comparable to those of the beverage glass mortars except the hardened density due to the presence of lead in the CRT glass. Decreasing the particle size of the CRT glass led to a decrease in fluidity, compressive strength and water absorption. However, the use of finer glass particles slightly improved the flexural strength and reduced the risk of expansion due to ASR due to its pozzolanic reaction. The experimental results indicated that treated CRT glass can be utilized as 100 % replacement of sand in cement mortar regardless of its particle size.     

Test Conditions Effect on the Fracture Toughness of Hollow Glass Micro-sphere Filled Composites

Abstract:  Low-density sheet-moulding compounds based on hollow glass micro-spheres are usually classified as syntactic foams if the filler content is relatively high. Syntactic foams are potentially suitable materials for applications where impact loads occur as they are able to reduce impact force. The addition of hollow micro-spheres tends to increase the specific values in terms of impact force and, marginally, in flexural modulus for high-volume fractions of micro-spheres. In this study, the effects of load rate and of immersion of the specimens in water up to 67 days were studied on the flexural mechanical properties and particularly on the fracture toughness, K _IC. Hollow micro-spheres (Verre ScotchitTM-K20) with epoxy and polyester polymer binder were used. Fracture toughness, K _IC, flexural stiffness modulus and ultimate strength were obtained as functions of load rate and immersion time. The increase of load rate tends to increase stiffness modulus, but effects on K _IC were found to be only marginal. Ultimate strength increases significantly with the increase of load rate for epoxy-based composites, but for the case of the polyester-based foams, only a negligible effect was observed. The increase of the immersion time in water tends to reduce stiffness modulus. K _IC decreases slightly after 15 days for the polyester-based composites and after 67 days for epoxy-based foams, and only negligible effects on ultimate strength were observed.     

Strength,sorption and abrasion characteristics of concrete using ferrochrome ash (FCA) and lime as partial replacement of cement

This paper presents the results of experimental investigations and microstructure study carried out to evaluate the possibility of utilization of ferrochrome ash (FCA), a waste product from ferroalloys industries for partial replacement of cement in concrete preparation. FCA is used in four different substitution rates such as 10, 20, 30 and 40% along with 7% lime. Various strength and durability tests were conducted to understand the effects of FCA and lime on performance of concrete. Test results revealed that replacement of cement by FCA in various % with 7% lime enhanced the 28 days compressive strength 1.5–13.5%, flexural strength 4.5–9%, bond strength 15–29%, abrasion resistance 10–23% and reduced the sorptivity 25–43%. The concrete containing 40% FCA and 7% lime, replacing 47% of ordinary Portland cement (OPC) in total, exhibited strength of normal concrete or even more at all ages. XRD and petrography studies confirmed the results of mechanical and durability properties.     

A comparison study of the mechanical properties and drying shrinkage of oil palm shell and expanded clay lightweight aggregate concretes

For making artificial lightweight aggregate, selected raw materials are fed into a rotary kiln at high temperature. Providing such a high temperature is costly and generally, the process of making artificial lightweight aggregate is not environmentally friendly. The use of natural lightweight aggregate for making lightweight concrete can lead to low-cost construction. The use of a solid waste lightweight aggregate namely oil palm shell (OPS) as coarse aggregate, is not only environmentally friendly but leads to a low-cost material. This study is a comparison between some engineering properties of OPS lightweight concrete and an artificial lightweight (expanded clay) concrete with low water to cement ratio, along with having good workability and without any segregation. The test results show that OPS concrete has better mechanical properties and a higher efficiency factor than expanded clay lightweight concrete. The ceiling strength of expanded clay lightweight concrete occurs at an early age; while it happens in OPS concrete at a later age. The crack pattern of the tested specimens shows that OPS is much stronger than expanded clay. On the other hand, the compressive strength of OPS lightweight concrete is more sensitive to lack of curing. Although OPS lightweight concrete shows twice the amount of drying shrinkage than expanded clay lightweight concrete in the short term, this difference reduces significantly at later ages.     

纤维聚苯乙烯泡沫颗粒轻质土的制备及力学性能

为促进轻质土在岩土工程中的广泛应用,添加改性聚丙烯纤维改善其力学性能,通过无侧限抗压强度试验分析探讨了纤维聚苯乙烯泡沫（EPS）颗粒轻质土强度-变形特性、受压破坏模式和无侧限抗压强度的影响因素,并运用SEM从微观层次上分析了其力学机制。结果表明:不同EPS颗粒、纤维及水泥掺量时,纤维EPS颗粒轻质土的应力-应变曲线不同;EPS和水泥掺量是强度的主要影响因素,其次为纤维掺量;强度随EPS掺量的增大而显著降低,随水泥掺量增大而显著提高;未加纤维的EPS颗粒轻质土松散且易破碎,强度骤然丧失;添加纤维能提高轻质土的峰值强度、残余强度、整体性和韧性,改善其脆性破坏模式;但EPS掺量较高（大于干土质量的3%）时,纤维与水泥土粘结有限,EPS颗粒轻质土力学性能改善效果较弱;EPS颗粒为空心蜂巢结构,纤维表面布满针状的水泥水化物并形成空间网状结构。所得结论表明纤维改善了轻质土力学性能。      

Pozzolanicity of finely ground lightweight aggregates

This paper examines the pozzolanic behavior of finely ground lightweight aggregates with a mean particle size between 4 and 26 μm. Cement pastes are made with a 20% mass replacement of cement with finely ground lightweight aggregates, fly ash, quartz, and limestone in addition to a control paste with no cement replacement. Isothermal calorimetry, thermogravimetric analysis, and compressive strength testing as well as thermodynamic calculations are performed on these pastes. Isothermal calorimetry and compressive strength testing are shown to not be able to clearly distinguish and quantify the pozzolanic response of the finely ground lightweight aggregates, fly ash, quartz, and limestone when they are used in cement pastes. However, thermogravimetric analysis and thermodynamic calculations clearly show that the finely ground lightweight aggregates are pozzolanic through the consumption of calcium hydroxide. A pozzolanic reactivity test based on isothermal calorimetry also confirms that the finely ground lightweight aggregates are pozzolanic. These results indicate that finely ground lightweight aggregates are pozzolanic and could be used in concreting applications.     

空心玻璃微珠对阻尼固体浮力材料力学性能影响研究

通过空心玻璃微珠（HGB）的体积分数、粒径、偶联剂改性等系列实验,总结分析了空心玻璃微珠对阻尼固体浮力材料力学性能的影响。结果表明,随着空心玻璃微珠体积分数的增加,浮力材料的吸水率逐渐增大,而密度、压缩强度和阻尼损耗因子逐渐降低;随着空心玻璃微珠粒径的增大,浮力材料的吸水率和阻尼损耗因子逐渐增加,而密度、压缩强度逐渐减小;添加偶联剂可有效改善空心玻璃微珠与环氧树脂的界面结合性,提高浮力材料的性能。      

Effect of metakaolin on the near surface characteristics of concrete

Results on an investigation dealing with the effect of metakaolin (MK) on the near surface characteristics of concrete are presented in this paper. A control concrete having cement content 450 kg/m³ and w/c of 0.45 was designed. Cement was replaced with three percentages (5, 10, and 15%) of metakaolin weight. Tests were conducted for initial surface absorption, sorptivity, water absorption and compressive strength at the ages of 35, 56, and 84 days. Test results indicated that with the increase in MK content from 5 to 15%, there was a decrease in the initial surface absorption, decrease in the sorptivity till 10% metakaolin replacement. But at 15% MK replacement an increase in sorptivity was observed. All mixtures showed low water absorption characteristic i.e. less than 10%. Compressive strength shared an inverse relation with sorptivity. Higher MK replacements of 15% are not helpful in improving inner core durability, even though it helps in improving surface durability characteristics.     

Compressive strength development of binary and ternary lime–pozzolan mortars

This study considers the compressive strength development of broad range of hydraulic lime mortars prepared with a range of commercially available alumino-silicate by-products and modern pozzolanic additions. Specifically this paper considers the effect of mineral addition selection, binary and ternary combinations, pozzolan content and the effect of curing conditions on the compressive strength development of hydraulic lime based mortars. The study was undertaken as the initial phase of a broader investigation considering the feasibility of producing modern, sustainable hydraulic lime–pozzolan concretes with comparable strengths to Portland cement based concretes. The aim of the initial phase was to identify a small number of additions, and combinations thereof, which would result in a structural strength lime–concrete when scaled up from mortars to concretes.In the absence of a definitive source of information on the mechanical properties of hydraulic-lime mortars prepared with binary and ternary combinations of alumino-silicate by-products, 22 combinations consisting of Natural Hydraulic Lime (NHL5) and a range of possible additions, identified from historical and current practice, were prepared. The results have shown that combining an eminently-hydraulic NHL5 with silica fume and ground granulated blastfurnace slag can produce mortars with a 28-day compressive cube strength of around 28 N/mm², at a water-to-binder (w/b) ratio of 0.5. This is eight times the strength of an equivalent mortar prepared with NHL5 alone and broadly speaking comparable with that of low-heat cementitious mortars. The contribution of the pozzolanic reaction to the strength of hydraulic lime mortars is discussed for a range of alumina-silicious materials and combinations thereof.     

Comparison of test methods to assess pozzolanic activity

Assessment of the pozzolanic activity of cement replacement materials is increasingly important because of the need for more sustainable cementitious products. The pozzolanic activity of metakaolin, silica fume, coal fly ash, incinerated sewage sludge ash and sand have been compared using the Frattini test, the saturated lime test and the strength activity index test. There was significant correlation between the strength activity index test and the Frattini test results, but the results from these tests did not correlate with the saturated lime test results. The mass ratio of Ca(OH)₂ to test pozzolan is an important parameter. In the Frattini test and strength activity index test the ratio is approximately 1:1, whereas in the saturated lime test the ratio is 0.15:1. This explains why the saturated lime test shows higher removal of Ca(OH)₂ and why the results from this test do not correlate with the other test methods.     

Effects of cold-bonded fly ash aggregate properties on the shrinkage cracking of lightweight concretes

This paper presents an experimental study on the restrained shrinkage cracking of the lightweight concretes made with cold-bonded fly ash lightweight aggregates. Two types of fly ash having different physical and chemical properties were utilized in the production of lightweight aggregates with different strengths. Afterwards, lower strength aggregates were also surface treated by water glass and cement–silica fume slurry to improve physical and mechanical properties of the particles. Therefore, a total of eight concrete mixtures were designed and cast at 0.35 and 0.55 water–cement ratios using four types of lightweight coarse aggregates differing in their surface texture, density, water absorption, and strength. Ring type specimens were used for restrained shrinkage cracking test. Free shrinkage, creep, weight loss, compressive and splitting tensile strengths, and modulus of elasticity of the concretes were also investigated. Results indicated that improvement in the lightweight aggregate properties extended the cracking time of the concretes resulting in finer cracks associated with the lower free shrinkage. Moreover, there was a marked increase in the compressive and splitting tensile strengths, and the modulus of elasticity.     

A water sorptivity test for martar and concrete

This paper describes a test rig to measure the uni-directional water absorption of mortar and concrete. The test data acquisition is controlled by purpose written software installed on a PC and the results are utilised directly to obtain the sorptivity measured in g/mm²/min^1/2. As an example the apparatus was used to obtain the sorptivity of mortar in which the ordinary Portland cement was partially replaced by ground waste brick obtained from different sources. The results presented demonstrate the validity of the test, and the apparatus and the methodology are shown to be of sufficient sensitivity in detecting the differences between the sorptivities of the various mortars tested. The variation in the sorptivity with curing time and mixture composition was determined. The paper also gives the results of total water absorption test conducted on the sorptivity test specimens, after being reconditioned, and the results of compressive strength tests for all the mortars investigated.     

Portland-limestone cements. Their properties and hydration compared to those of other composite cements

The new European Standard EN 197-1 emphasizes the development of composite cements. In Greece a variety of pozzolanic and/or hydraulic materials are used as cement main constituents. Until now, limestone could be used only as a filler (up to 3% w/w), but since 2001 (application of EN 197-1) it can also be used as a main cement constituent. In this work a comparison between limestone and some of the materials that are already used in Greece is presented. An ordinary Portland cement and three Portland-composite cements containing limestone, natural pozzolana or fly ash were produced. The grinding process was designed in order to produce cements of the same 28 day compressive strength. The mechanical and physical properties of the cements were measured and hydrated products, formed after 1–28 days, were identified by means of XRD. The composite cements present significant differences as far as the clinker fineness, the development of the strength, the water demand and the hydration rate is concerned. The production of Portland-limestone cements seems to be very challenging, due to the satisfactory properties of the limestone cements as well as the low cost and the high availability of limestone in Greece.     

Participation of coloured glass cullet in cementitious materials

In this paper fundamental aspects of the pozzolanic activity of the three most common coloured glass cullet in Greece and of vitrified fly ash were studied. Furthermore, the problem of ASR in mortar systems with high content of finely ground glass cullet was estimated. The chemical behaviour of the added cullet in the cement was determined by XRD, DTA-TG and SEM observations and additionally mechanical tests, metal leaching examination and pore measurements were carried out. Green cullet appeared to be the most pozzolanic material followed by the flint glass. None of studied materials have shown any expansion, due to the deleterious ASR reaction. The potential utilisation of coloured glass cullet in various cementitious products is very encouraging especially for decorative and architectural applications.     

Use of natural zeolite as a supplementary cementitious material

Natural zeolite, a type of frame-structured hydrated aluminosilicate mineral, is used abundantly as a type of natural pozzolanic material in some regions of the world. In this work, the effectiveness of a locally quarried zeolite in enhancing mechanical and durability properties of concrete is evaluated and is also compared with other pozzolanic admixtures. The experimental tests included three parts: In the first part, the pozzolanic reactivity of natural zeolite and silica fume were examined by a thermogravimetric method. In this case, the results indicated that natural zeolite was not as reactive as silica fume but it showed a good pozzolanic reactivity. In the second part, zeolite and silica fume were substituted for cement in different proportions in concrete mixtures, and several physical and durability tests of concrete were performed. These experimental tests included slump, compressive strength, water absorption, oxygen permeability, chloride diffusion, and electrical resistivity of concrete. Based on these results, the performance of concretes containing different contents of zeolite improved and even were comparable to or better than that of concretes prepared with silica fume replacements in some cases. Finally, a comparative study on effect of zeolite and fly ash on limiting ASR expansion of mortar was performed according to ASTM C 1260 and ASTM C 1567. Expansion tests on mortar prisms showed that zeolite is as effective as fly ash to prevent deleterious expansion due to ASR.