Abstract:

In order to drive the green and low-carbon transformation of the building materials industry， the steel slag （SS）， ground granulated blast furnace slag （GGBS） and fly ash （FA） were used to replace 40% （in mass， the same below） of cement， and systematically studied the effects of different mix designs on the mechanical properties，capillary water absorption characteristics and microscopic properties of composite cementitious materials under thermal wet curing. The test results show that in terms of mechanical properties， when the content of FA is 10%， the flexural and compressive strength of mortar specimen are higher than those of 0% and 20% FA. At the same time， with the increase of SS content and the decrease of GGBS content， the flexural and compressive strength of mortar specimen also decrease. In addition， when the SS content is 10% and GGBS content is 20%， the flexural strength and compressive strength are second only to the group with SS content of 0% and GGBS content of 30%， The increase in flexural strength is similar for both， while the increase in compressive strength is higher for the former than for the latter. In terms of capillary water absorption characteristics， with the increase of SS content， the capillary water absorption coefficient also increases gradually， reflecting the deterioration of pore structure. In terms of microscopic properties， the increase of SS content will reduce the active components of composite cementitious materials， but the appropriate amount of SS can promote the hydration reaction of GGBS.

Key words: steel slag, ground granulated blast furnace slag, fly ash, thermal wet curing, capillary water absorption