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The most widely used material after water is the concrete composite. However, it is commonly accepted that concrete is weak in tension compared to its compression, therefore, conventionally, it is usually reinforced with steel rebars. Recently, reusing of waste plastic materials has become a norm among researchers whom used it in different forms in improving some mechanical properties of the concrete such as impact and tensile strength. However, using PET plastic strips as a replacement of main steel rebars is a novel idea. Therefore, in this study the experimental laboratory work is conducted to investigate the possibility of using waste plastic strips as a replacement of the main reinforcement steel bars to promote the flexural capacity of concrete beams at 28 days. For this purpose, a total number of 10 beams were casted with dimensions of (200mm x 200mm x 1200mm) to investigate the effects of using waste plastic strips in enhancing the bending capacity of the beams. The results showed that the incorporation of the plastic strips can improve the load carrying capacity and toughness of the concrete beams compared to unreinforced concrete beams.

Effects of various elevated heating temperatures on mechanical properties of normal concrete containing recycled tire rubber as a fine aggregate (RTRFA) has been investigated in this paper. Five different concrete mixes were prepared in the laboratory. In each mix Ordinary Portland Cement, natural coarse and fine aggregate, water and RTRFA are used with fine aggregate replacement ratios (0%, 6%, 12%, 18% and 24%) by weight. In the laboratory, 60 cylindrical specimens (100mm diameter × 200mm high) and 60 cubic specimens (150×150×150mm 3) were prepared. The concrete specimens were exposed to four different heating temperatures: Control (Not heated), 200, 400, and 600°C, and tested according to British standards to observe the postheating mechanical properties. These properties included density and mass loss, split tensile strength and compressive strength. The results showed a linear decrease in compressive strength with higher temperature degrees and percent replacement of fine aggregate by RTRFA. Moreover, the concrete's tensile strength fluctuated as it increased at 6% of rubber replacement then linearly declined at further replacement rates. Finally, some crucial conclusions of heating rubberized concrete have been drawn.

To increase the capacity load carrying of the beams, post tensioned metal straps are fully wrapped around the beams in their tensile zone in this study. In total four normal R.C beams with the depth of 160 mm, height of 240 mm and total length of 2100 mm are cast and tested under four-point load testing. The number of variables is kept to minimum of two which are the number and location of the straps. It is found that using post tensioned metal straps fully wrapped around the beams can increase the load-carrying capacity of the beams by 36% at least and 39% at a max. The main factor in influencing the rate is the location of the straps. A complete guide on using the material along with its application on the beams are explicitly described in the paper.

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