Aerated concrete (AC) is lightweight concrete in which air voids are captured in the mortar by means of the addition of an aerating agent to meet specific requirements of density and strength. Aerated concrete displays brittle failure in tension, however, and thus an alternative solution to make the concrete more ductile and reduce the problem of cracking is to add steel bars or steel fibre. The aim of this study is thus to investigate the effect of steel fibres on the compressive strength, flexural strength, stress-strain relationship, modulus of elasticity, density, sorptivity, and water absorption of aerated concrete with such fibres as compared to plain aerated concrete. End-hooked steel fibres with lengths of 35 mm and 60 mm with aspect ratios of 64 and 67 respectively were used in this study, with a volume friction (Vf) of 1.5%. The results showed that the effect of the aspect ratio (Lf/df) on flexural strength was most prominent, and that the compressive strength of the fibre reinforced aerated concrete (SFRAC) increased significantly and the density increased slightly, while the water absorption was decreased. The sorptivity of the SFRAC with short fibres was similar to that of standard AC, with this being increased slightly with the longer fibres. However, the stress-strain relationship in tension increased most significantly. Overall, 1.5% of steel fibre of 60 mm length provided the highest flexural strength at 28 days.

Concrete is considered a low tensile resistance material and a weak material against cracking. The weak properties of concrete has been enhanced by utilizing fibers to reinforce it. In this research, the effects of the polypropylene fibers on several properties of plain concrete have been studied. It was found that the polypropylene fibers has enhanced the concrete ductility and the concrete crack control. The compressive strength of plain concrete has been increased by adding polypropylene fibers to it and also the flexural and splitting strengths. The best results were at fibers ratio of 1%. When the polypropylene fibers ratio has changed different effects on concrete properties have been obtained.

Concrete is the most popular construction material and has a relatively high compressive strength and it does not crack under its own weight, but its tensile strength is much lower compared to its compressive strength. The compressive strength can be changed according to the water to cement ratio during concrete formation or mixing, while the tensile strength rises when additives are used, concrete needs reinforcing steel, and added to plain concrete, resulting in reinforced concrete. In other terms, concrete consists of sand or fine aggregate, gravel (which is a coarse aggregate), water, and cement (which is considered a bonding material), and it is a brittle material that needs reinforcement and also some admixtures to improve its low tensile resist. This research aims to increase and improve some mechanical properties of concrete by using waste tiles as coarse aggregate. The study includes replacing normal aggregates with waste tile and using them as crushed aggregate with 25, 50, 75, and 100% replacement. Studies show increment in compressive and tensile strength and flexural strength by using waste tile aggregate compared with ordinary concrete; compressive strength increased from 34.1 MPa for reference mixes without waste tiles to 39.8 MPa using waste tiles. The study included improving all mixes with polycarboxylate superplasticizer and gaining high strength concrete, especially mixes with 50, 75, and 100% waste tile aggregate; the compressive strength with totally waste tile replacement gave the highest value of compressive strength, which was 57.5 MPa, tensile and flexural strength also increased by using waste tile aggregate, and 100% replacement shows optimum values of mechanical properties in this study.

Portland cement-based grouting compound is called GP-Grout employed to produce a sort concrete as a replacement from the weight of cement in mixes and strengthened with steel nails to enhance the mechanical properties. GP-Grout replaced cement by 25%, 50% and 75% while the steel nails as locally steel fibres were used with 0.25%, 0.5%, 1%, 2 % and 3% by volume of concrete. GP-Grout powder enhanced mechanical properties of ordinary concrete especially; the compressive strength by increasing from 34 to 70 MPa as well as other properties including tensile and flexural strength with clear improvement by adding the steel nails at a ratio of 3% by volume and the results were 5.67, 9.81 MPa respectively.

Concrete is a material that is strong in compression but weak in tension. To overcome this issue, reinforcement must be used to improve the tensile strength of the concrete. However, it is acknowledged that steel has its drawbacks, such as the fact that it has a high cost and corrosion potential, and the rebar is heavy, non-renewable, and non-environmentally friendly. Thus, this experimental study investigates the potential product of economical reinforced concrete slabs using eco-friendly materials. Firstly, to enhance the concrete properties, a compressive, tensile, and flexural test, also a concrete with the addition of polypropylene fiber outlasted the control mix design in terms of strength and durability. The results included the control mix (CM), F1 0.25%, F2 0.50%, F3 0.75%, and F4 1%. The specimen with the highest compression and tensile strength was 24.28 MPa and 3.15 MPa, respectively, for the F1 specimen with 0.25% short fibers. Secondly, the bending test was carried out on ten slabs to check the structural behavior of these slabs reinforced with reed rods as the eco-friendly material. The good results of the bearing capacity of a partially reinforced concrete slab with a reed have been obtained at 23.8 kN. Meanwhile, to obtain better results, this research has enhanced the behavior of the concrete slab by improving the concrete's properties by adding polypropylene synthetic microfiber to the mixed concrete. In addition, giant reeds treated with epoxy increase the bonding strength with concrete, improve tensile strength properties, and reduce the absorption of reeds. Therefore, the bearing capacity results of the reed-reinforced concrete slab became the best, which were 35.83 kN. Thus, reinforcement of one-way slabs by reed partially with appropriate diameters could be substituted to obtain good performance in the reconstruction of low-cost buildings. As a result, economical reinforced concrete slabs have been produced using eco-friendly materials. Doi: 10.28991/CEJ-2023-09-06-010 Full Text: PDF