关键词: 碱矿渣胶凝材料;碱浓度;模数;抗压强度;水化产物

Abstract: Granulated blast furnace slag was activated by using water glass (sodium hydroxide was added in to adjust modulus) to prepare alkali activated slag paste specimens.Effect of alkali concentrations of 4%, 6% and 8% and moduli of 0.75, 1.00, 1.50 and 2.00 of the activator on the compressive properties and hydration products of alkali activated slag was studied by using compressive strength test, X-ray diffraction (XRD) and thermal analysis (TG-DSC) techniques.The results show that when a lower modulus was used, such as 0.75 and 1.00, compressive strength of alkali activated slag decreased with the increase of alkali concentration.While when the modulus used was higher, such as 1.50 and 2.00, the specimens could obtain the maximum compressive strength when alkali concentration was 6%.Under same alkali concentration, modulus of 1.50 could make the specimens get the maximum compressive strength.The main hydration products of alkali activated slag was C-S-H gels, certain amount of C-A-S-H gels was also formed simultaneously.Besides, small amount of gismondine (CaAl2Si2O8· 4H2O) was also detected in the system.Hydrotalcite (Mg6Al2(OH)6CO3· 4H2O) was found in some of the mixes. Larger amount of C-S-H gels was formed in the alkali activated slag system with higher alkali concentration.Use of higher modulus, such as 1.50 and 2.00, was beneficial for the formation of C-S-H gels in the system.When a lower alkali concentration/modulus was used, the C-S-H gels in alkali activated slag was more crystalline.Compared to the degree of crystallinity, amount of C-S-H gels was more influenced on the compressive strength of such system.

Key words: alkali activated slag cementitious material;alkali concentration;modulus;compressive strength;hydration product