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Previous researches have shown that partial replacement of aggregates with Expanded Polystyrene (EPS) in concrete mixes reduces both the density and compressive strength of concrete, but enhances its durability. As there is no effort was made to determine the optimum EPS/gravel replacement ratio in a concrete mixture, this study triedl to determine this ratio. An experimental investigation is performed by using six different concrete mixes produced by partially replacing gravel with an equivalent volume of EPS beads. The adopted volumetric replacement ratios of coarse aggregate by EPS were (11%, 22%, 33%, 44%, and 55%). The results indicated that A drop in the density of both the fresh and hardened concrete was found to be in the range (of 0% to 35%) compared to the corresponding density value of the base mix (without EPS). Concrete compressive strength was also found to drop in the range (0% to 91%) compared with the corresponding value of the base mix. Within the limit of this work, it was found that the 22% replacement volumetric ratio of coarse aggregate with EPS is the optimum ratio based on a ratio of the drop in density to the drop in compressive strength. Generally, it was concluded that the optimum volumetric replacement ratio lies between 15% to 30%, according to the comparison with other prior studies.

Laying of service pipes such as sewage pipes, electricity pipes, and sometimes water pipes ducts and others had presented some problems especially if it gathered in one place. One of the best solutions to minimize the problems and solve the piping and other services is using longitudinal and transverse opening in beams (BLTO), especially when high strength concrete (HSC) is used. HSC beam that performed experimentally by a researcher and implemented in this study by finite element method. ANSYS software was utilized to prove the experimental results with using the same properties, geometry, materials, and conditions which the comparison included the force-displacement relationship ultimate load capacity, maximum displacement, and crack pattern. The verification process between the experimental program and theoretical one demonstrated that there is a good convergence between the obtained results between the two results. The similarity in the outcomes showed that the matching between the experimental and numerical in force by (99%) and in displacement by (94%). These variances were due to the small difference in the condition of experimental and theoretical side which the numerical considered ideal condition. Also, this study examined the behavior of (RC) beam have longitudinal and transverse opening. The registered failure mode of beam was flexural failure although of presence of shear cracks but the flexural cracks were the controller in the behavior.