Abstract: In view of the insufficient mechanical properties of lightweight concrete, various fibers are added to lightweight concrete to improve its mechanical properties. The influences of adding ceramsite, basalt fiber, and polypropylene fiber on the compressive strength and maximum shear strength of concrete were investigated by using orthogonal test. Results reveal that replacing part of coarse aggregate with ceramsite could effectively reduce the dead weight of concrete, but also greatly reduce the compressive strength; ceramsite could improve the maximum shear strength of concrete, with a maximum rising rate of 13.7%. Both basalt fiber and polypropylene fiber could enhance the compressive strength and maximum shear strength of concrete, boosting the compressive strength by up to 9.7% and 5.7% respectively and maximum shear strength by 36.2% and 13.1% respectively. In addition, a prediction model for the compressive strength and maximum shear strength of hybrid fiber concrete is established.

Key words: hybrid fiber reinforced concrete, orthogonal test, compressive strength, maximum shear strength, strength prediction model