Static and Dynamic Compression Performances of Hybrid Fiber-Reinforced Lightweight Aggregate Concrete

In this study, basalt fiber and polypropylene fiber with different volume ratios were mixed into lightweight aggregate concrete (LAC), and the static compressive strength and dynamic compressive performance of LAC mixed with fiber were tested. The influence of basalt fiber and polypropylene fiber on the stress-strain relationship and energy conversion relationship of LAC was analyzed. The results show that basalt fiber and polypropylene fiber with an appropriate volume ratio are beneficial to enhance the strength and toughness of LAC, but the mixing effect is better. When the volume ratio of mixed fibers is 0.2%, the compressive strength, elastic modulus, peak strain, and ultimate strain are increased by 61.9%, 23.57%, 32.81%, and 45.14%, respectively, compared with the LAC without fibers. Based on the statistical damage theory, the compressive damage constitutive model of fiber LAC is established; fiber improves the ductility and energy absorption capacity of LAC and shows better impact resistance. Finally, based on modern SEM microscopic testing technology and EDS testing technology, the internal structure and chemical element composition of ordinary LAC and fiber lightweight aggregate were compared and analyzed. The internal compactness of the aggregate concrete improves the strength and toughness of the lightweight aggregate concrete, which reveals the mechanism of the fiber on the LAC from a microscopic point of view.

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