Carbonation performances of steel fiber reinforced geopolymer concrete

Steel fiber reinforced geopolymer concrete (SFRGC) shows excellent mechanical properties comparable to steel fiber reinforced concrete. However, research on the durability of SFRGC is scarce. This paper presents the carbonation performances of SFRGC, including the carbonation depth and strength variation during carbonation. The results show that the permeability and carbonation depth of SFRGC are close to those of plain geopolymer concrete (GC). Their carbonation depths are much deeper than those of cement concrete because of the lower alkali content of the geopolymer matrix. Carbonation hardly influences the final flexural strength of plain GC, but the flexural strength of SFRGC declines significantly during carbonation because of the decrease in steel fiber-geopolymer matrix bond strength. The scanning electron microscope results show that the failure mode in uncarbonated SFRGC specimens is fiber rupture, while in carbonated SFRGC specimens, fiber pullout is the failure mode. These findings suggest that using SFRGC in the atmosphere is not recommended.

Automated summary

Steel fiber reinforced geopolymer concrete (SFRGC) has excellent mechanical properties similar to steel fiber reinforced concrete, but research on its durability is limited. This study investigates the carbonation performance of SFRGC, including carbonation depth and strength variation. The results show that SFRGC has similar permeability and carbonation depth to plain geopolymer concrete (GC), but the carbonation depth is greater than that of cement concrete due to lower alkali content in the geopolymer matrix. Carbonation has a significant negative impact on the flexural strength of SFRGC, mainly due to the decrease in steel fiber-geopolymer matrix bond strength. Using SFRGC in the atmosphere is not recommended based on these findings.