STRENGTH AND DRYING SHRINKAGE OF ALKALI-ACTIVATED SLAG PASTES CONTAINING REACTIVE MGO
Alkali-activated slag (AAS) cements are sustainable alternatives to Portland cement due to the low initial capital cost of their raw materials and the savings on energy and resources,leading to much lower CO2 emissions.However,several issues exist,which prevent the widespread use of AAS including the difficulty of handling the caustic alkalis,and their high shrinkage levels.This paper investigates the effect of reactive MgO,as a less caustic and an expansive mineral additive,hence a promising alternative,on the strength and drying shrinkage of AAS.The AAS was prepared using two different alkali activators,namely,waterglass/NaOH and sodium carbonate.Two MgOs with different reactivities were used in three dosages in the range of 2.5-10% by weight of slag.It was found that reactive MgO can effectively reduce the drying shrinkage without sacrificing the strength of AAS and sometimes even enhancing it.From X-ray diffraction results,both reactive MgOs were found to rapidly react with the slag to form hydrotalcite-like phases leaving no brucite in the pastes.However,the effect of reactive MgO on the properties of AAS pastes differed significantly depending on the activator type,MgO content and reactivity.
slag reactive MgO strength drying shrinkage hydration products
Fei Jin Kai Gu Abir Al-Tabbaa
Department of Engineering,University of Cambridge,Trumpington Road,Cambridge,United Kingdom,CB2 1PZ Department of Engineering,University of Cambridge,Trumpington Road,Cambridge,United Kingdom,CB2 1PZ;
国际会议
长沙
英文
233-242
2014-06-01（万方平台首次上网日期，不代表论文的发表时间）