This paper presents the study carried out on the utilization of Waste Glass Powder (WGP) as supplementary cementitious material in concrete. The evaluation of the influence of WGP on the mechanical properties of concrete was carried out by casting and testing of concrete samples as per ASTM standards (cylinders and beam elements). The control samples were designed to represent field conditions with a target compressive strength of 20,000 kPa. The Portland cement in concrete was substituted with WGP in proportions of 0%-35% by weight, in increments of 5%. Two curing domains were adopted in the preparation of the test samples to evaluate the effect of pozzolanic material wherein the tested samples were cured for 28, 56, and 84 days. The study results indicated a reduction in compressive strength of concrete up to 10% with partial replacement of cement with 25% of WGP when standard curing of 28 days was adopted. Furthermore, with the same replacement proportion and prolonged curing for 84 days, the gap in strength reduction was reduced by 5%. However, a significant decrease in workability was noted between the control concrete samples and glass powder infused concrete. Furthermore, the Waste Glass Powder Concrete (WGPC) exhibited an improved flexural strength with the modulus of rupture for WGPC being 2% higher than control concrete at the age of 84 days. Based on the results of this study it was concluded that 25% replacement of cement with WGP provides an optimum replacement ratio. Doi: 10.28991/cej-2020-03091620 Full Text: PDF

The increase in the concrete demand due to the rapid industrialization and urbanization may lead to a shortage of natural resources. Therefore, the use of recycled material in the batching of concrete will be helpful to meet the demands of the time without compromising the quality of concrete production. One such waste material produced in Pakistan is waste marble powder (WMP) that is generated from the marble factories during cutting of the marble stones, which in turn have a damaging effect on the environment. This study is based on the utilization of WMP as a partial substitute of the sand in concrete production and its various effect on the mechanical properties of the concrete. Different types of tests (unit weight, workability, compressive strength, splitting tensile strength, and water penetration) were carried out at 0-80%, of sand replaced with WMP, at increments of 20%. In all mixes, the ratio of water to cement was kept constant and the effects of curing conditions were studied at 14, 28, and 70 days. It was observed that with the incorporation of WMP, the workability and unit weight of concrete decrease proportionally to replacement percentage, whereas mechanical properties of concrete increase up to a certain percentage and then decrease. The maximum improvement in compressive strength was achieved at a 40% replacement, with a slight improvement in the tensile strength at 20% replacement. The water penetration test revealed a decrease in permeability with the increase in WMP percentage. Based on the results, it was recommended to use WMP up to 40% in the concrete mix as a replacement of sand.

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The inherent vulnerability of beam-column joints to seismic loading and steel congestion are two major research problems connected with beam-column joints of moment-resisting frames. The experimental study presented herein addresses these research questions and seeks to solve them by using Polyvinyl Alcohol based Engineered Cementitious Composite (PVA-ECC) in beam-column joints without transverse shear reinforcement. The study included the manufacture and shake table testing of two 1:3 reduced scale one bay two-story moment-resisting frame models using simulated earthquake motions. To evaluate the performance of ECC beam-column joints without shear reinforcement, two frame models, one with and the other without shear reinforcement in the beam-column joints, were prepared and tested. The acceleration time history record of the 1994 Northridge Earthquake USA was used for the excitation of specimens at different levels to produce progressive damage up to the near collapse state. The observed damage mechanism of tested models was recorded, and the response parameters, including floor displacement and acceleration, were measured. The measured data was processed to develop a lateral force-displacement envelope curve for the supposed prototype frames and calculate their seismic design factors (ductility, overstrength, and response modification). Comparison of the seismic performance parameters of the two prototype frames reveal that the ECC beam/column joint without shear ties performed marginally inferior to the ECC beam-column joints having shear ties but it still achieved a 75% larger R-factor compared with the code specified value.

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