Development And Properties Of High Performance Cementitious Grout For Coupler

Assembling precast concrete structure has been one of the important directions of architectural industrial development. The joints of this concrete structure are commonly connected by reinforcement sleeve. High performance of cementitious grout for coupler is the key technology of this connecting structure. So it is necessary to develop high performance grouting material.New type of grouts which can be used in prefabricated concrete structure were prepared by adding river sand and additives in the Sulphoaluminate cement-Portland cement-Gypsum composite cementitious system. Orthogonal experiment was adopted to optimize the mix proportion of this grouts. Influence of single and double mixing with silica fume, fly ash or mineral powder on the fluidity, strength and vertical expansion ratio was studied. And the reason for these effects were analyzed and discussed from microcosmic view by scanning electron microscopy (SEM). Through this research, conclusions are drawn as follows:(1) The compound method of this new sleeve grouting material was obtained. Here list its proportion:sand-binder ratio 1.0, portland cement 15%, gypsum content 7.5%. The performance of this grout can completely meet the standards. It has excellent properties when connecting prefabricated members.(2) Effects of silica fume, fly ash and mineral powder on performance of this grouting material was studied. The results show:1) The paste which mixed with fly ash has the most advantage in initial fluidity. As to the 30min fluidity retention, mineral powder has more obvious effects. The influence of fly ash and mineral powder compound addition on fluidity is greater than other two additives.2) Silica fume has great influence on early strength of grouting material. The enhancement of on late strength become more obvious. The highest strength comes from the scheme of silica fume and mineral powder compound mixing.3) Fly ash has the greatest effect on of all the specimen. The compound additives consisted of fly ash and mineral powder has significant influence on 3h vertical expansion ratio. But for 24h vertical expansion ratio, it is the least.(4) Conclusions drawn from SEM:With silica fume adding, the unreacted ones adhered to surface of hydration production. When the paste mixed with fly ash, there is no reaction in early period. Along with the time passing by, reaction shows up in later three days. On the 28th day, there exists only little amount of fly ash in reaction system. The structure of this new sleeve grouting material become more compact with addition of mineral powder.