Ultra High Performance Concrete (UHPC) represent as one of the most concrete progressive development so that it can be improved the strength, durability, reliability, and resilience of the concrete structures. The availability of local materials play the main role in the major step in making the economic mix jobs by saving their materials and effort and decrease the concrete cost. So in this paper, the parameters including the curing regimes, of sand gradation, binder type, and content, and steel fiber content were investigated to show their effect on concrete’s compressive strength. The obtained results showed that the curing regime that consists of 5 days (2 days at 60°, 3 days at 80°) given the highest strength than other curing regimes. Finer sand, Silica Fume, steel fibers cause a considerable increasing in compression strength. Various relationship were obtained illustrating the effect of studied parameters with concrete strength.

This paper is related to a laboratory program for the shear strength of reinforced concrete corbels (RCC) cast with or without recycled aggregate (RA) by investigating the main parameters affecting the corbels behavior including the replacement aggregate recycling ratio, fcu, and shear span to effective depth ratio a/d. Eight specimens were cast and tested. The obtained results were compared with ACI and EC2 codes. It is found that the ACI code and E2 code give sensibly conservative results when compared with the findings of the present work for all tested specimens regarding RA, concrete strength, and a/d. Also, the experimental results show that the presence of recycled aggregate decreases slightly both cracking and failure loads. Furthermore, the failure load development due to the effect of compressive strength is more effective with the presence of recycled aggregate, and the 50% ratio of RA was the suitable ratio in elaborate crack and failure loads. Finally, the reduction of the span-depth ratio (from 0.50 to 0.35) increases the crack and failure load by 8.1% and 20.2%, respectively, leading to confirm that the corbel strength is much sensitive to decreasing span-depth ratio compared to the associated deflections.

This paper deals with the investigation factors effecting core strength estimation by conducting an experimental study which included casting of six plain concrete beams. For each beam, 12 cubes were cast in addition to twenty-four core samples were extracted. The investigated factors involved the concrete compressive strength, concrete type, core extracting direction, core location, core depth in the beam, and the damage factor. It obtained results showed that the ratio of compressive strength in the vertical to horizontal cast direction is (1.075) and (1.080) for the traditional and superplasticizer concrete, respectively. Also, the depth factor of bottom to top zone strength in vertical cast direction is (1.110) and (1.066) for traditional concrete and the super plasticizer concrete respectively, while the location factor of center zone in vertical cast direction corresponding to (1.088) and (1.103). Finally, the damage factor is directly proportional with the concrete strength for both concrete types.

This study aims is to investigating the structural capacity of fibbers reinforced deep beams with opening under pure torsion. The deep beams were made of high strength concrete. The openings were made in the web with different shapes (circular and square), sizes and located at the mid span. Seventeen deep beam specimens were casted and they experimentally investigated throughout this study. The constants in this study are beam dimensions and compressive strength for concrete. The effects of the shape, size and locations of opening on the torsional behaviour of deep beams under torsional loading are studied in the paper. The results showed the square opening is weakest due to the concentration effect which increases the stresses and the opening size participate main role in strength of deep without steel fiber. Also, the steel fibre in which the presence of steel fiber causes increasing in the torsion strength about (30-32) of tested specimens.