Dynamic mechanical properties of carbon fiber reinforced geopolymer concrete at different ages

In order to improve the strength and toughness of geopolymer concrete (GC) at different ages under impact load, using slag and fly ash as cementitious materials, NaOH and sodium silicate as alkaline activators, carbon fiber as reinforcement, carbon fiber reinforced geopolymer concrete (CFRGC) was prepared. The dynamic compression test of CFRGC was carried out by F 100 mm SHPB test system. The effects of age (3 d, 7 d, 28 d) and fiber content on the dynamic mechanical properties of CFRGC were studied, and the strengthening and toughening effects of carbon fiber on GC were analyzed. In addition, the strengthening and toughening effects of carbon fiber on GC and ordinary Portland cement based concrete (PC) were compared and analyzed. The results show that the performance indicators of CFRGC at different ages have strain rate effect under impact load, and the dynamic compressive strength and specific energy absorption of CFRGC increase approximately linearly with the strain rate. With the increase of age, the dynamic compressive strength and specific energy absorption of CFRGC increase, and the strain rate sensitivity of dynamic compressive strength and specific energy absorption also increases. With the increase of carbon fiber content, the dynamic compressive strength and specific energy absorption of CFRGC increase first and then decrease, and the strain rate sensitivity of dynamic compressive strength and specific energy absorption also increase first and then decrease. When the carbon fiber content is 0.2%, the dynamic mechanical properties of CFRGC are the best, and the strain rate sensitivity of performance indicators is the strongest. Carbon fiber has strengthening and toughening effects on GC and PC. When the fiber content is 0.2%, carbon fiber has the best strengthening and toughening effects on GC and PC. The strengthening and toughening effects of carbon fiber on GC is better than that of PC. Compared with 28 d, carbon fiber has better strengthening and toughening effects on GC at the ages of 3 d and 7 d.

Automated summary

Carbon fiber reinforced geopolymer concrete (CFRGC) was prepared using slag and fly ash as cementitious materials, NaOH and sodium silicate as alkaline activators, and carbon fiber as reinforcement, in order to improve its strength and toughness under impact load at different ages. The dynamic mechanical properties of CFRGC were studied by conducting dynamic compression tests using a F 100 mm SHPB test system. The effects of age (3 d, 7 d, 28 d) and fiber content on the mechanical properties of CFRGC were analyzed, and the strengthening and toughening effects of carbon fiber on geopolymer concrete (GC) were evaluated. The results show that CFRGC exhibits strain rate effect at different ages under impact load, with the dynamic compressive strength and specific energy absorption increasing approximately linearly with the strain rate. The carbon fiber content has an influence on the mechanical properties of CFRGC, with an increase initially followed by a decrease in the dynamic compressive strength and specific energy absorption. The strain rate sensitivity of the mechanical properties also follows a similar trend with the increase in carbon fiber content. The optimal fiber content for CFRGC is 0.2%, which exhibits the best dynamic mechanical properties and the highest strain rate sensitivity. Carbon fiber has strengthening and toughening effects on both GC and ordinary Portland cement based concrete (PC), with the most significant effects observed at a fiber content of 0.2%. The strengthening and toughening effects of carbon fiber on GC are superior to those of PC. The effects of carbon fiber on GC are more pronounced at 3 d and 7 d compared to 28 d.