Influence of Using High Volume Fraction of Silica Fume on Mechanical and Durability Properties of Cement Mortar

The high pollution caused by CO2 emission and the high level of energy consumed during cement manufacturing led the researchers to look for alternative techniques to reduce these environmental effects. One of these techniques includes reducing the content of cement in the mix by replacing it with supplementary cementitious materials such as fly ash, slag, silica fume, and so on. Many previous studies dealt with the utilizing of the high volume of supplementary cementitious materials, such as fly ash and slag. However, limited studies investigated the impact of silica fume on mortar or concrete properties in percentages of more than 30%. Thus, to produce environmentally friendly concrete, this study was performed to investigate the effect of the high replacement level of cement with silica fume on the properties of cement mortar. Six replacement proportions of silica fume (0%, 30%, 40%, 50%, 60% and 70%) were used in this paper. This paper used the flow rate, compressive strength, water absorption, bulk density and volume of permeable voids tests to test the effect of silica fume on different mortar characteristics. The results indicated that the best mixture among all other mixes was found by 50% substitution of silica fume. At this percentage, an enhancement in compressive strength of nearly 83%, 74% and 75% at 7, 28 and 56 days, respectively and an improvement in water absorption resistance by 8% compared to the control mixture were achieved

Properties of a Low-Carbon Binder-Based Mortar Made with Waste LCD Glass and Waste Rope (Nylon) Fibers

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

Influence of mechanical activation on the behavior of green high-strength mortar including ceramic waste

Solid waste management is a significant environmental issue for countries because of the need for huge landfills. The ceramic tile waste powder (CWP) is one of the wastes. Conversely, cement production, the main ingredient in concrete, emits large quantities of greenhouse gases, a significant environmental concern. Therefore, substituting some of the cement in concrete with CWP is an issue that deserves investigation to reduce the environmental impact of both materials. Accordingly, this study aims to investigate the influence of the grinding time and proportion of CWP as a substitute for cement on the properties of high-strength mortar (HSM). Three grinding times (10, 15, and 20 minutes) and three replacement percentages (10%, 20%, and 30% by weight) for CWP were adopted for each time. Ten mixtures (including the reference mixture) were executed. The fresh (flow rate), mechanical (compressive strength) durability (ultrasonic pulse velocity, dynamic elastic modulus, water absorption, density, percentage of voids and electrical resistivity) and microstructural properties were examined. The life cycle assessment (LCA) was also addressed. The results showed that the mechanical activation had a pronounced effect on the durability properties (especially water absorption and percentage of voids) more than on the compressive strength. Generally, a sustainable HSM (with more than 70 MPa of compressive strength) can be produced in which 30% of the cement was replaced with CWP with almost comparable performance to the CWP-free mortar. Furthermore, LCA results showed that mortars containing 30% CWP ground for 15 mins (GT15CWP30) had the lowest GWP per MPa

Potential Use of Rendering Mortar Waste Powder as a Cement Replacement Material: Fresh, Mechanical, Durability and Microstructural Properties

The difficulty of decomposing solid waste over time has made it a significant global problem because of its environmental impact and the need for large areas for disposal. Among these residues is the waste of the rendering mortar that is produced (falls to the ground) while applied to wall surfaces. The quantity of these materials may reach 200 to 500 g/m2. As a result of local urban development (in Iraq), thousands of tons of these wastes are produced annually. On the other hand, the emission of greenhouse gases in the cement industry has had a great environmental impact. One of the solutions to this problem is to reduce the cement content in the mix by replacing it with less emissive materials. Residues from other industries are considered a relatively ideal option due to their disposal on the one hand and the reduction of harmful emissions of the cement industry on the other hand. Therefore, this research aims to reuse rendering mortar waste powder (RMWP) as a possible alternative to cement in mortar. RMWP replaced the cement in proportions (0, 10, 15, 20, 25, and 30% by weight). The flow rate, flexural and compressive strengths, ultrasonic pulse velocity, bulk density, dynamic modulus of elasticity, electrical resistivity, and water absorption tests of the produced mortar were executed. Microstructural analysis of the produced mortar was also investigated. Results indicated that, for sustainable development, an eco-friendly mortar can be made by replacing cement with RMWP at a rate of 15%, resulting in a 17% decrease in compressive strength while maintaining or improving durability properties. Moreover, the microstructure became denser and more homogeneous in the presence of RMWP

Performance Comparison of 45° and 90° Herringboned Permeable Interlocking Concrete Pavement

Pavement deterioration is mainly caused by high traffic loading and by increased levels of runoff water resulting from storms, floods, or other reasons. Consequently, this issue can be efficiently solved by employing permeable pavement, such as permeable interlocking concrete pavement (PICP) to control water runoff and endure increased traffic loads. This study investigates the performance of PICP, in both 45° and 90° herringboned surface patterns, in terms of the infiltration of volumes of water, runoff water volumes, and the ability of pavement to withstand static loading. All the related tests in this study were implemented using a lab apparatus that was fabricated as a simulator for rainfall. Various conditions were adopted during the performance tests, including the application of longitudinal slopes (0, 2.5, 5, and 7.5%), side slopes (0, 2.5, and 5%), and different rainfall intensities (25, 50, 75, and 100 L/min). The results indicated that at high rainfall intensities (75 and 100 L/min), PICP with the 45° herringboned surface pattern had the highest volume of infiltrated water and the lowest runoff water at all the adopted longitudinal and side slopes. In addition, PICP with the 45° herringboned surface pattern showed higher resistance to deflection under a static loading test than the 90° herringboned pattern under the same conditions. Therefore, PICP with a 45° herringboned surface pattern showed supremacy in terms of runoff reduction and load resistance in comparison to PICP with a 90° herringboned pattern. Even though there are differences between the two types of PICP, they are both strongly recommended as alternatives to regular pavement

Performance of Green Mortar Made From Locally Available Waste Tiles and Silica Fume

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 impact of grinding time on properties of cement mortar incorporated high volume waste paper sludge ash

Cement is considered a base material in preparing blending mixtures that applying in various projects in the civil engineering field. Nevertheless, the cement production process cause indubitable negative environmental influences such as emitting CO2. The production of cement produces around 7% of the global CO2 emissions. Thus, searching for alternate binders in building processes to minimise or substitute cement has been one of the social problems. A by-product or waste products are among the potential alternatives to the mentioned problem. The present investigation involves the consumption of paper sludge ash (PSA) waste as cement replacement to produce environmentally friendly, cementitious material. Limited studies were addressed the PSA grinding time impact on mortar or concrete properties. Moreover, limited studies replaced the cement with high volume of PSA. Therefore, during this study, the effect of grinding time and replacement level (up to 50%) of the PSA on the surface electrical resistivity and compressive strength of mortar were investigated. Three grinding periods (in addition to without grinding), two replacement levels and three testing ages were considered. The results indicated that grinding the PSA for 10 minutes and use it to replace up to 50% of the cement content have similar mechanical and durability performance to ordinary Portland cement after 28 curing days. This innovative binder will also cause a major difference in decreasing the building materials cost and CO2 emissions

Impact of Substitute Portland Cement with CKD on the Mechanical and Durability Characteristics of Cement Mortar

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

Utilization of locally produced waste in the production of sustainable mortar

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

Recycling of Eggshell Powder and Wheat Straw Ash as Cement Replacement Materials in Mortar

Cement is among the important contributors to carbon dioxide emissions in modern society. Researchers are studying solutions to reduce the cement content in concrete to minimize the negative impact on the environment. Among these solutions is replacing cement with other materials, such as waste, which also poses environmental damage and requires landfill areas for disposal. Among these wastes are eggshell powder ash (ESPA) and wheat straw ash (WSA), which were utilized as cement substitutes in green mortar production. Thirteen mixtures were cast, one as a reference without replacement and twelve others that included replacing ESPA and WSA (single and combined) with cement in 2%, 4%, 6%, and 8% proportions of cement's weight. The mechanical (compressive and flexural strength), microstructural (SEM), and thermogravimetric analysis (TG/DTA) properties of all mixtures were examined. The results showed a remarkable improvement in mechanical properties, and the best improvement was recorded for the (4%ESPA+4%WSA) mixture, which reached 73.3% in compressive strength and 56% in flexural strength, superior to the reference mixture. Furthermore, SEM analyses showed a dense and compact microstructure for the ESPA and WSA-based mortars. Therefore, the WSA and ESPA wastes can be recycled and utilized as a substitute for cement to produce an eco-friendly binder that significantly improves the microstructural and mechanical characteristics of mortar. In addition, combining the two materials also presents a viable option for creating a sustainable ternary blended binder (with cement) that boasts superior properties compared to using the WSA or ESPA individually