<p>One of the major challenges faced by researchers is to recycle industrial wastes in a manner that reduces their environmental impact in nature. An experimental study was carried out to determine the suitability of using chopped tire rubber as reinforcements in green and sustainable geopolymer concrete, with the purpose of using them as nonstructural products. The geopolymer mixture was made by mixing of fly ash powder, fine aggregate, and Superplasticizer in Na2SiO3/NaOH solution. Mixtures were divided into four different groups, with constant water to fly ash ratio of 0.12 and alkaline dosage of 45% by weight of fly ash, based on the recycled chopped tire rubber (CTR) content: 0, 10, 20, and 30% by volume of fine aggregate with two maximum sizes (2 and 4mm). Hardened properties of resulted geopolymer like compressive strength, density; and ultrasonic pulse velocity were examined at 28d. Besides that, X-Ray diffractometer and Scanning Electron Microscope were used in order to observe the microstructure of the resulted geopolymer concrete. In view of the consequences for this study, it is preferable to replace no more than 10% of fine aggregate in geopolymer concrete by CTR. In addition, according to SEM photographs, increasing the CTR content more voids will be pronounced and thus, decreasing the mechanical performance.</p>
Carbon dioxide emissions and the consumption of natural resources related to the cement manufacturing have prompted the need to develop more sustainable and environmentally friendly types of concrete. Geopolymer concrete is considered eco-friendly concrete because it is free of cement. Otherwise, nanomaterials have been introduced into geopolymer concrete in previous works with the aim of improving its properties. However, very restricted studies have focused on the combined utilizing of nano-clay and nano-titanium in geopolymer concrete. Therefore, in the current research, geopolymer concrete was developed from industrial wastes (fly ash; FA) by using a novel mixture of different nanomaterials: nano-clay (NC) and nano-TiO2 (NT). Mixtures with constant water to FA (12 %), and different alkaline contents: (40 %, 45 %, and 50 %) by FA, were performed and divided into three groups. In the first group, only FA was used as a binder, meanwhile, a combination of (FA+NC) and (FA+NT) was used separately in group two (binary). In the third group, (FA+NC+NT) were mixed together (ternary). Several hardened tests have been investigated: compressive, tensile strengths and density. Also, microstructural characteristics were monitored using XRD and SEM tests. The findings revealed that the addition of nanomaterials obviously enhanced the density of the microstructure, reducing the pores of the produced geopolymer concrete. Moreover, the compressive strength was enhanced up to 38 % for NC, and 24 % for NT in the binary blends while the improvement reached 55 % in the ternary blends.
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).
The continuous depletion of natural resources used in concrete require vital replacement materials to reduce the consumptions of the natural resources. Moreover, the growth in the population increases the construction of new houses to accommodate the population, which increases the demand concrete and other construction materials. The replacement of the existing building materials with the newly materials proceed from recycling the waste materials for example, flooring tiles, which is usually disposed of in landfills without any benefit in Iraq. Therefore, this study aims to recycle locally available floor tiles waste by using it as a total alternative to fine aggregate to enhance the sustainability by reducing the depletion of natural aggregates. Three types of waste tiles were used in this research, which are marble, granite, and porcelain. Four mortar mixtures were designed, casted and tested in the research. One control mixture made from natural sand aggregate and three mixtures in which the sand was fully replaced with each of marble, granite, and porcelain waste tiles with comparable grading as that for sand. The cement was partially replaced with a 10% silica fume (SF) in all mixtures. The flowability, mechanical and durability tests of mortar mixtures were investigated. The results indicated that the combination of porcelain waste tiles aggregates with 10% silica fume imparted superior performance compared to all other mixtures with improvements of 99% in the compressive strength, 53% in the flexural strength and 17% in the water absorption resistance.
The disposal of solid waste has become one of the critical issues facing governments due to its environmental impact due to the difficulty of its decomposition. Electric cable waste (ECW) is one of these wastes. Its production increased in Iraq over time due to the demolition and reconstruction of residential and commercial homes. Therefore, reusing it in other industries, such as concrete technology, is a promising solution. Limited studies have studied the utilization of these local wastes as a replacement for natural sand in the short and long term. Therefore, the aim of this study is to investigate the properties of mortar incorporating recycled ECW as a partial replacement for sand. The fine aggregate (natural sand) was replaced by weight with ECW ranging from 0 to 25 % in the step of 5 %. Flow rate, as well as mechanical properties (compressive strength, flexural strengths, and density), were executed at 7, 28, and 360 days. It was found that the best performance was obtained at a replacement ratio of 5 % of ECW with mechanical strengths close to or slightly less than the reference sample and a 17 % reduction in density. However, regarding sustainability, it is possible to produce a lightweight structural mortar with a density lower than 1700 kg/m3 and a compressive strength of 36 MPa at 360 days when replacing the natural sand with 25 % ECW.
