Performance of Carbon Fiber Filament Reinforcing Cement Mortar

This paper aims to study the effect of Carbon Fiber Filament (CFF) with different ratios and lengths on the physical and mechanical properties of cement mortar. An experimental program included 3 cm fixed length of CFF with 0, 0.25, 0.5, 0.75, and 1% different ratios by weight of cement addition were used in cement mortar cubes. Another experimental program of 0.5% CFF ratio with 1, 2, 3, 4, and 5 cm different lengths by weight of cement addition was used in cement mortar prisms. The physical and mechanical properties of cement mortar containing CFF were experimentally investigated at 7 and 28 days of curing. Workability, by means of flow table test, were measured. Density is conducted for cubes and prisms at the age of 28 days. At ages of 7 and 28 days, compressive and flexural strengths were studied. The study showed a reduction in workability with the increase of CFF ratios and lengths by 0.0 to 2.7% and by 0.9 to 5.4% respectively. Moreover, an improvement in density, compressive, and flexural strengths was observed. At ages of 7 and 28 days, the results showed that compressive strength increased by 33 and 31% respectively at 0.5% of CFF ratio while the flexural strength increased by 125 and 327% respectively with CFF length of 5 cm. Doi: 10.28991/cej-2021-03091753 Full Text: PD

Evolution of Durability and Mechanical Behaviour of Mud Mortar Stabilized with Oil Shale Ash, Lime, and Cement

The investigation into earthen construction technologies and materials is now acknowledged as a crucial area requiring further research. Earthen mortars are prevalent in both modern and traditional construction due to the abundance of earth material, their favorable thermal properties, and their low embodied energy. The objective of this study is to support the use of natural materials collected from north Jordan to enhance the mechanical properties and durability of mud mortar. The local soil was stabilized using Oil Shale Ash (OSA), Ordinary Portland Cement (OPC), and lime for producing mud mortar. Particle size analysis, plastic limit, liquid limit, XRD, and XRF were applied to assess the geotechnical characterization and mineral composition of the earthen stabilizers and local soil. In order to examine the mechanical properties (specifically compressive strength) and durability characteristics (such as water absorption and shrinkage) of mud mortar, a total of 8 mixtures were prepared. One of these mixtures served as a control, while the others were created by substituting soil with varying proportions of OSA, cement, and lime. The results show that the mud mortar contained 10% OSA and 10% cement, which exhibited the highest compressive strength. Moreover, an increase in the proportion of OSA in the soil led to a decrease in absorption and linear shrinkage, indicating that OSA is an effective stabilizing agent for mud mortar. Doi: 10.28991/CEJ-2023-09-09-06 Full Text: PD

A Green Way of Producing High Strength Concrete Utilizing Recycled Concrete

Multiple studies have investigated the influence of recycled aggregates derived from concrete waste on the efficacy of structural concrete manufactured in recent times. By utilizing recycled aggregates obtained from construction and demolition debris, it is possible to safeguard natural aggregate resources, reduce the demand for landfill space, and promote the utilization of sustainable building materials. However, compared to natural aggregate, bonded cement mortar on recycled concrete aggregate exhibits higher porosity, greater water absorption capacity, and lower strength. The mechanical and durability characteristics of freshly poured and hardened concrete made from recycled concrete aggregate are adversely affected as a result. This study presents comprehensive experimental research aimed at examining the residual mechanical properties and resistance to acid attack of normal and high-strength mixes of recycled aggregate concrete (RAC) using the compressible packing model. Recycled aggregate was employed as both coarse and fine aggregate. The recycled concrete samples were prepared in a manner that corresponded to the proportions of both the coarse and fine aggregates. Twelve mixtures were designed and cast, and their performance was evaluated based on various strength parameters (compressive strength, splitting tensile strength, and flexural strength) as well as acid attack resistance properties (porosity and ultrasonic pulse velocity). The findings indicate that recycled concrete aggregate can be utilized in the production of high-strength concrete, with mechanical property values that are significantly acceptable compared to concrete containing natural aggregates. Moreover, the addition of Silica Fume as a cement replacement in concrete plays a crucial role in enhancing sulphate resistance. In terms of concrete product utilization, recycled concrete and its significance in this study played a crucial role in environmental preservation. Doi: 10.28991/CEJ-2023-09-10-08 Full Text: PD

Effect of alkali activated limestone-silica fume blended precursor on performance enhancement of recycled aggregate concrete

The utilization of Recycled Aggregates (RA) from Construction and Demolition (C&D) waste, has been reported to be an efficient way of dealing with the environmental issues encountered by our planet nowadays. However, due to the poor quality of RA, its incorporation in high – grade civil engineering applications been limited. It is essential that adequate process of treatment methods be incorporated into the production of RA to enhance its properties and optimize its use. This study is carried out to determine the effects of an alkaline NaOH activated by limestone powder (LSP) and silica fume (SF) to improve the properties of various concrete mixes produced with either recycled concrete aggregate (RCA), or recycled cement block aggregate (CBA). Fifteen mixes were designed to examine the effects of different parameters, RA replacement levels, various w/c ratios and different enhancement methods on the properties of recycled aggregate concrete (RAC). The study examined the effects of the proposed enhancement method on the physical characteristics of RCA and CBA. Compressive strength, splitting tensile strength, flexural strength, pull-out, and water absorption of the different concrete mixes were measured to determine the effectiveness of the enhancement method proposed. The enhanced RAC produced by CBA and RCA showed an increased 28-day compressive strength at 0.35 w/c ratio of up to 51 MPa and 44 MPa, respectively, suitable for structural applications. The flexural strength, tensile splitting strength, and bonding strength values at 0.35 w/c ratio of the enhanced RAC produced with treated CBA were 28%, 6%, and 8% higher than that of the RAC produced with treated CBA. Whereas, the flexural strength, tensile strength, and bonding strength of the enhanced RAC produced with treated RCA were 1%, 3%, and 5% higher compared to the RAC produced with treated RCA. The improved mechanical performance of the enhanced RAC produced by CBA or RCA was attributed to the effects of the geopolymer solution treatment in filling and sealing the voids and gaps on the CBA and RCA surface, leading to a better packed structure, reducing the water absorption, and improving the aggregate impact value. The treatment technique proposed can be a powerful tool for promoting the use of RA in the construction industry and expanding its application