ITZ BETWEEN FLY ASH AND CEMENT MATRIX IN HVFA SCC
To detect the probability of the interracial transition zone (ITZ) between fly ash and cementmatrix, high volume fly ash self-compacting concrete (HVFA SCC) was prepared.Microstructures of the ITZ and hydration products of fly ash were investigated by SEM usingHVFA SCC specimens conserved for 28d at standard curing conditions. It is found that ITZbetween fly ash and cement matrix is distinguished. The width of the ITZ is about 5-10μm,among which about 1μm near fly ash particles is water membrane. Lots of ettringite andportlandite exist in the tinier ITZ. Width of the tinier ITZ becomes smaller and smaller andthe ITZ graduates away along with the development of pozzolanic reaction between fly ashand portlandite. Based on the experimental results, it can be explained why high volume flyash cementitious materials exhibit lower strength and weaker resistance to carbonation andfreeze-thaw recycles at early ages. It is necessary to grind or to activate fly ash and to adoptlower water-cementitious materials ratio incorporating strict curing so that the second ITZ inHVFA SCC is able to be mitigated or eliminated, and the durability and resistance to harmfulions attack of HVFA SCC are enhanced.
Y.Q.Jiang L.Guo Y.F Pan J.G.Chert
School of Materials Science and Engineering,Hohai University,China
国际会议
南京
英文
575-581
2008-10-13（万方平台首次上网日期，不代表论文的发表时间）