Basic mechanical properties and size effect of polypropylene fiber reinforced concrete
To explore the size effect among strength indexes of polypropylene fiber reinforced concrete,the com-pressive strength,splitting tensile strength,bending flexural strength and fracture energy of concrete specimens with different sizes and different polypropylene fiber content were tested.The results showed that with the in-crease of polypropylene fiber content,the tensile strength,flexural strength and fracture energy of concrete specimens with all sizes increased significantly,but the compressive strength decreased.According to analysis of the load-displacement curve,failure mode,tension-compression ratio and folding-compression ratio of con-crete specimens,it was found that the maximum strain of compressive strength increased by 250%and the ten-sion-compression ratio increased from 1/11.2 to 1/7.3 after adding 1.5 kg/m3 polypropylene fiber,which showed that adding polypropylene fiber could improve the mechanical characteristics of concrete and make the material change from brittleness to toughness.The relationship among strength indexes and size effect were dis-cussed,and the conversion relationship among compressive strength,tensile strength and flexural strength was established,which provides a theoretical basis for structural design and analysis of polypropylene fiber rein-forced concrete.