WITHDRAWN: An Experimental Study on the Size Effect of Maximum Coarse Aggregate on the Inherent Anisotropy of Concrete's Compressive Strength

Abstract

This study conducts an experimental investigation into the inherent anisotropy of concrete during compressive tests, utilizing different material orientations (MOs) and mechanical parameters in the concrete. Specifically, the research 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 (MCASs) in different MOs. The study includes designing three mixtures of normal concrete for an approximately constant compressive strength using three of rounded MCASs 4.75, 9.5 and 19 mm. Concrete cubes and lintels are cast, both unreinforced, along with three standard cylinders for each MCAS with diameter of 100 mm and 200 mm height (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 from the concrete cubes and lintels at orientations 0°, 22.5°, 45°, 67.5° and 90° and standard cylinders are tested as well. The results show that the compressive strength and compressive fracture energy of concrete are significantly influenced by MCAS and MO. As the MCAS increases, the compressive strength increase and compressive fracture energy decrease. Additionally, it is observed that the compressive strength significantly changed respect to MO. The lowest compressive strength is observed at an angle of 45° with size 4.75 mm, while the highest is recorded at an angle of 0° with size 19 mm. The highest compressive strength was recorded for the sizes 19, 9.5 and 4.75 mm, respectively.