Experimental Study On Dynamic Compression Performance Of PVA-ECC At Room And Low Temperature

With the continuous development of China’s economic construction,many large projects have been built in cold areas,the performance of the structure in low temperature conditions is completely different from room temperature,in order to ensure the safety and applicability of the project,it is also necessary to understand the mechanical properties of the concrete class materials in low temperature conditions.The emergence of Engineering fiber reinforced Cementitious Composites(ECC)is a good solution to the shortcomings of low tensile strength and brittleness of concrete materials,and has become a hot spot for research in recent years.At present,scholars at home and abroad have conducted a lot of research on the static mechanical properties of ECC materials,but there is less research on the impact resistance of the materials,especially on the dynamic mechanical properties of the materials under low temperature conditions.In this paper,a dynamic compression test was conducted on PVA-ECC specimens at room temperature and different low temperature conditions using a Hopkinson compression bar device(SHPB)with a diameter of 50 mm.The main study contents is as follows:(1)The static compressive strength tests were conducted on PVA-ECC specimens at different temperatures,and the results showed that: the static compressive strength of PVA-ECC at different temperatures increased with the increase of fiber doping,and the growth rate was approximately the same.The static compressive strength of PVA-ECC at the same fiber doping increased with the decrease of temperature,but the growth rate was not the same in different temperature ranges,and when the temperature was lowered from 0℃ to-30℃ the growth rate of compressive strength was significantly greater than the growth of strength when the temperature was lowered from room temperature to 0℃.(2)The dynamic uniaxial compression test was conducted on PVA-ECC specimens at room temperature,and the results showed that: with the increase of strain rate,the dynamic peak stress,peak strain,impact toughness and dynamic increase factor(DIF)of PVA-ECC specimens were significantly increased with obvious strain rate effect,but the dynamic elastic modulus of the specimens was not significantly increased.With the increase of fiber doping,the dynamic peak stress,dynamic peak strain and impact toughness of PVA-ECC specimens showed an increasing trend,but the dynamic elastic modulus was slightly decreased.(3)The dynamic uniaxial compression test was carried out on PVA-ECC specimens at low temperature,and the results showed that: the number of cracks decreased and the crack width increased with the decrease of temperature,and the specimens showed obvious freeze brittleness,the descending section of stress-strain curve gradually became steep,the dynamic peak stress and dynamic elastic modulus increased linearly with the decrease of temperature,showing obvious temperature effect,but the dynamic peak strain and impact toughness decreased compared with the room temperature condition.The dynamic mechanical properties of PVA-ECC specimens under different low temperature conditions with strain rate and fiber doping were similar to the room temperature condition,with the increase of strain rate and fiber doping,the dynamic peak stress,peak strain and impact toughness increased.This paper contains of 37 figures,14 tables and 87 references.