Effect of Cylindrical Core and Pipe Samples Oriented in Different Orientations on Compressive Strength of Normal Concrete Using Various Sizes of Coarse Aggregate: An Experimental Study

This study focuses on performing a series of comprehensive tests to analyze compressive strength, compressive fracture energy and failure angle of concrete samples with varying maximum coarse aggregate sizes in different material orientations. The study includes designing three mixtures of normal concrete for an approximately constant compressive strength using three sizes of rounded maximum coarse aggregate (4.75, 9.5 and 19) mm. Two types of samples are prepared for comparison: core samples and pipe samples. Core samples were extracted from unreinforced concrete cubes and lintels, along with three standard cylinders for each coarse aggregate size with diameter of (100) mm and height of (200) mm (high to diameter ratio 2). After a curing period of 28 days in water, by using core drilling machine (75) samples with diameter (54) mm and height (97) mm (high to diameter ratio 1.8) are drilled at five inherent orientations (0°, 22.5°, 45°, 67.5° and 90°). Pipe samples preparation of plastic pipes involves cutting and fixing them at five inherent orientations (0°, 22.5°, 45°, 67.5° and 90°). The pipes are then filled with a mixture for each size of coarse aggregate (4.75, 9.5 and 19) mm. After water curing for 28 days, cutting to obtain (75) samples with diameter (47) mm and height (95) mm (high to diameter ratio 2). The results show that the compressive strength and compressive fracture energy of concrete are significantly influenced by the maximum size of coarse aggregate and the material orientation. The lowest compressive strength values for core and pipe samples were recorded at angle 45, while the maximum compressive strength for core samples was recorded at angle 0 and for pipe samples at angle 90. The highest compressive strength was recorded for the sizes (19, 9.5 and 4.75) mm, respectively.