The aim of this study is to develop Lightweight self-compacting concrete (LWSCC) mixtures using locally sourced waste materials such as Expanded Polystyrene Beads (EPS) and Waste Plastic Fibers (WPFs) which are all available abundantly available in Republic of Iraq at little or no cost. The fresh, hardened and mechanical properties of these LWSCC were studied, followed by results analysis. Five different mixes of LWSCC were prepared in term of WPF content (0.25, 0.5, 0.75, 1.0, and 1.25 %), in addition to the control mix (R mix) and lightweight concrete (E mix) made of EPS content as a replacement of coarse aggregate. The study showed that the LWSCC produced with these waste materials were decreased the density (lightweight) of the concrete mixes as EPS tend to form more clumps, absorb water and make the mix dry. Therefore, concrete mixtures were adjusted accordingly to be able to offset the workability caused by the addition of EPS. The increase in WPF content decreased the workability due to clumping that occurred in the mixing phase. The analysis of mechanical properties of the LWSCFRC specimens revealed that there was not much improvement. While LWSCC with 100% of EPS replacement as coarse aggregates and 1.25% WPFs provides the best flexural toughness performance
This study presents an investigation of the mechanical properties of normal concrete reinforced with discarded steel fibers (DSFs) resulting from tire manufacturing. DSFs were added to concrete in two different volume fractions of (0.25 %, and 0.5 %), and these fibers have dimensions of (40 mm length×0.92 mm diameter). The results showed that the compressive strength of the concrete was enhanced by (8.8%, and 3.3%) by adding of DSFs. However, the workability of concrete decreased at all added ratios. While the density is slightly changed. Also, the results indicate that the modulus of elasticity shows slight increases by (3.06%, and 2.25%). Additionally, the incorporation of DSFs improves the splitting tensile strength and modulus of rupture significantly. For concrete mixes having volume fractions of 0.25% and 0.5%, the splitting tensile increased by (7.89%, and 23.68%), and the modulus of rupture increased by (6.67% and 25.58%), respectively. It was concluded that using this type of discarded fibers can improve the mechanical properties of concrete as an alternative type for other types of industrial fibers.
Organic soils are problematic soil for various engineering applications due to their high compressibility and low shear strength which need to be improved. For many soil improvement techniques, using waste materials, such as fly ash (FA), is a practical and sustainable process. In this research, FA and geopolymer were used e used to reduce organic soil's compressibility. A one-dimensional consolidation test was performed to evaluate the organic soil's consolidation and compressibility properties. The geopolymer was prepared using 20% FA and of sodium hydroxide ratio and sodium silicate alkali solutions. The geopolymer specimens were first cured for 2 hours at 45 and 65 oC, then cured for further 28 days at room temperature. The consolidation test results showed that FA-based geopolymer is effective in stabilizing organic soils due to the observed improvement in the compressibility, consolidation, and permeability characteristics. The compression index decreased by 98.16%, and the permeability decreased by 95%.
The most concerning issue confronting the planet these days is the ascent in Carbon dioxide (CO2) levels to record levels. The cement industries are answerable to between 6-8 % of worldwide CO2 emitting. In construction sectors, researchers tried to contribute in decreasing of CO2 in atmosphere produced by industry and using that was released in air. Accelerated CO2 curing is one of the methods used to get benefit from CO2 in the air. In this paper, CO2 concentration in addition to pressure, relative humidity and period of curing all had a significant influence upon the features of Cement – Based Composites. Results showed that using CO2 curing with different and specific properties of fibers (types, quantities, circumstances and lengths) improved the most mechanical properties and enhanced durability such as: strength, stiffness, ductility, toughness, porosity, and absorption.