This study aims to investigate the effect of ternary combination of silica fume, and glass and ceramic waste as a partial replacement of cement on selected properties of mortar in the presence of steel-polypropylene hybrid fibers. Thirteen mixtures have been made: one control mix and twelve mixes in which the cement has been replaced by constant proportion (30% of cement weight) of ternary combination of silica fume, and glass and ceramic waste. The steel fibers have been added in the proportion of 1% while polypropylene fibers have been applied in the percentages of 0.25%, 0.5% and 1% (by volume for both fibers types). The flow rate, the compressive and the flexure strength and the bulk density tests have been examined. The hardened tests have been carried out at age of 28 days. Results have showed that the flow rate values have been reduced after replacing cement with the combination of silica fume, and glass and ceramic waste. Moreover, it has been found out that the compressive and flexure strength values for all combination mixtures have been higher than that for control mixture. The enhancement ranges have been 31% to 62% for compressive strength and 3% to 25% for flexure strength. In addition, results have demonstrated that there has been no significant change in bulk density values for cement replacement mixtures related to the one for control specimens.
Waste and by-product materials have a negative impact on the environment due to the pollution associated with them. The conversion of these materials from useless or harmful to valuable substances by, for example, incorporating them into concrete, can thus be considered to be an issue worthy of consideration in the search to reduce this impact. This study aims to prepare and characterise the ash produced from rice husk wastes to discover the ash's effect when used as a cement replacement in recycled aggregate concrete in the presence of styrene butadiene rubber (SBR). The rice husks were burned in the oven at 550 to 650 °C for two hours. Afterward, the rice husk ash (RHA) was characterised using X-rays, FT-IR, and grain size analysis tests. Thereafter, four concrete mixes, 0% RHA + 0% SBR, 1% RHA + 1% SBR, 3% RHA + 1% SBR, and 0% RHA + 1% SBR were made. The RHA was used as cement replacement, while the SBR was used as mixing water replacement, with percentages measured by weight for both materials. Crushed clay bricks were employed as coarse aggregate for all mixes. Compressive strength tests were carried out at 7 and 28 days. The X-ray and FT-IR results demonstrate that an amorphous form of silica with good purity was produced from the prepared RHA. For concrete mixes, the results indicate an important enhancement in compressive strength obtained by using RHA.
This paper aims to investigate the influence of Silica fume proportion ratio in respect to the total amount of binder on compressive strength of reactive powder concrete cured in two curing systems. Four ratios of Silica fume (0%, 15%, 25% and 35%) as replacement of cement weight were considered. After de-molding, two curing systems were used: the first included immersing the cubic specimens in water at 24 ± 2°C until the test. In the second, the specimens were immersed in hot water at 105 ± 5°C (accelerated curing) for 48 hours, then in water at 24 ± 2°C until the test. The results show that mix which contains 25% Silica fume imparts more enhancement on compressive strength as compared to the control mix. Also, it was found that the second system of curing has more influence on compressive strength development than the first one, especially at earlier ages.
Environmental pollution due to CO2 emissions from the cement industry and the depletion of the natural resources of the aggregate used in the concrete industry call for the need to find alternatives to reduce these harmful effects. Some of these alternatives include the use of supplementary cementitious materials and the reuse of wastes from other industries as cement and aggregate replacement materials. Thus, this study was conducted to investigate the possibility of using autoclaved aerated (cellular) concrete blocks waste powder (CCP) that is locally produced as a partial substitute for cement or sand in mortar. Seven mixtures were cast. Three of them made by the substitution of the cement with CCP passed from 0.075 mm sieve (5%, 10 % and 15 % by weight), and other three mixtures comprised the replacement of natural sand with CCP of size 0.15−0.075 mm (5%, 10 % and 20 % by weight). A reference mixture (without replacement) was also performed for comparison purposes. The mechanical and water absorption properties were examined. Results indicated that among all tests examined, a sustainable mortar was produced by the substitution of the cement or sand with 10% CCP with an enhancement in the compressive strength without significantly affecting other properties of the mortar.
Building materials such as sand, cement, bricks, and steel are usually the main components of the construction sector. All these materials are produced from existing natural resources and they will cause substantial damage to the environment as a result of their continuous depletion. Moreover, during the manufacture of various building materials, especially cement, a high concentration of carbon dioxide is constantly emitted into the atmosphere. Therefore, to reduce this environmental damage as well as to save natural resources, this study was performed to recycle the wastes of some of building materials such as marble, granite and porcelain tiles and clay brick through using them as cement and aggregate replacement materials in cement mortar. Sixteen mixtures were cast for this study. In addition to the control, the mortar mixes were divided into five groups, three mixes in each group. In four of the five groups, cement was replaced in three proportions (5%, 10%, 15% by weight) with each of marble, granite, porcelain and clay brick waste powders (passing through 150-μm sieve). The fifth group included 100% replacing (by weight) of the natural sand with the marble, granite and porcelain tiles wastes (with a comparable gradation). The influence of these wastes on flow rate, compressive strength, flexural strength, bulk density, ultrasonic pulse velocity (UPV) and water absorption tests were observed. Results showed that it is possible to produce an eco-friendly mortar made with 100% recycled marble or porcelain aggregate with a significant improvement in the mechanical and durability properties in comparison with natural aggregate mortar.
Carbon dioxide emissions are one of the problems that arouses the interest of scientists because of their harmful effects on the environment and climate. The construction sector, particularly the cement industry, is a significant source of CO2. On the other hand, solid waste constitutes a major problem facing governments due to the difficulty of decomposing it and the fact that it requires large areas for landfill. Among these wastes are LCD waste glass (WG) and used rope waste. Therefore, reusing these wastes, for example, in concrete technology, is a promising solution to reduce their environmental impact. Limited studies have dealt with the simultaneous utilization of glass waste as a substitute for cement and rope waste (nylon) fiber (WRF). Therefore, this study aimed to partially replace cement with WG with the addition of rope waste as fibers. Thirteen mixtures were poured: a reference mixture (without replacement or addition) and three other groups containing WG and WRF in proportions of 5, 15 and 25% by cement weight and 0.25, 0.5 and 0.75% by mortar weight, respectively. Flow rate, compression strength, flexural strength, dry density, water absorption, dynamic modulus of elasticity, ultrasonic pulse velocity and electrical resistivity were tested. The results indicate that the best ratio for replacing cement with WG without fibers was 5% of the weight of cement. However, using WRF increased the amount of glass replacement to 25%, with an improvement in strength and durability characteristics.
Reactive powder concrete (RPC) is a special type of concrete that has excellent properties, especially compressive strength. However, one of the disadvantages of RPC is that it has a high cement content, which can reach 1000 kg/m3. Because of the high cost of producing cement and the greenhouse gas emissions associated with its manufacture, researchers have resorted to investigating alternatives to cement, including supplementary cementitious materials. Accordingly, this research aims to produce environmentally friendly RPC in which 50% of the cement was replaced by metakaolin (MK) and fly ash (FA) combinations. To achieve the aim of the study, three RPC mixtures: 10MK + 40FA, 15MK + 35FA, and control mixture (without replacement) were cast. The fresh and mechanical properties tests were performed. The results showed that the combination of MK and FA improved the fresh properties of RPC, while the hardening properties were decreased.
Cement mortar is a binding material that is made of cement, sand and water. In general, mixes of mortar are made of raw materials. However, using raw materials in producing mortar leads to many environmental and economic issues. One of the most common solutions to reduce these issues is replacing raw materials by waste and/or by-product materials; especially replacing cement. The aim of this research is to explore the characteristics of mortar mixes after partially replacing Ordinary Portland Cement (OPC) by Cement Kiln Dust (CKD) at three percentages (10%, 20% and 30%) in terms of initial and final setting time, compressive strength and Ultrasonic Pulse Velocity (UPV). The control mortar specimen (mortar containing OPC only) results were adopted for comparison with results of mortar mixes that incorporated CKD. Results showed that increment in CKD replacement percentages led to a decrement in the compressive strength and UPV and an increment in the setting time.
The fast growth in the construction sector has made the concrete one of the most essential materials in the world. Concrete industry consumes massive amounts of raw materials, such as fine and coarse aggregate. Nowadays the increasing amount of waste construction materials causes environmental problems. Certainly, the sustainable solution is to adopt these waste materials and reuse them again in order to save natural resources and decrease their consumption. This study aims to investigate the potential use of different waste materials such as ceramic, clay bricks, marble, glass, granite, porcelain, and concrete wastes as a partial replacement of fine aggregate in cement mortar. Each one of these materials has been used in two proportions, 10% and 20% as replacement of natural sand weight. The compressive and flexure strength tests at 28 and 56 days have been taken into account for hardening mortar. Results have showed that it is possible to produce sustainable mortar containing 20% of porcelain, glass or clay bricks waste as a replacement for natural sand with a significant improvement in compressive and flexure strength properties. In contrast, it has been found out that waste marble had a negative impact on the hardened properties of mortar especially at the later age (56 days).