Investigation On Preparation And Applications For A Super Early Strength Admixture Of Sulphoaluminate Cement

The performance of general Purpose Portland cement can satisfy the need of the common engineering construction, but it can not be applied in rapid construction engineering, such as quick-repair, emergency treatment and leakage-preventing engineering. Recently, the research and making of sulphoaluminate cement have rapidly developed. The cement has the properties of early strength, high strength, anti-frost, impermeability, low alkality and so on. Sulphoaluminate cement sets rapidly, it is not avail to construct for its setting time(such as repair and grouting engineering), but in other engineering(such as leakage-preventing engineering),it requires cement has rapid setting and high hour strength. In order to exert the potential and expend the application of the sulphoaluminate cement, it is necessary to improve the performances of the sulphoaluminate cement, and to prepare the super early strength additive whose setting time can be appropriately controlled.Based on the hydration theory of sulphoaluminate cement and strength theory of the concret, to find the admixtures which is suitable for sulphoaluminate cement and optimize the performances of sulphoaluminate cement.The influence of the content of every admixture on the performances of sulphoaluminate cement was researched. To meet the requirements of super early strength, the experiment of compound admixtures was studied, and drawing for the best admixtures content, and its applications was studied.The research shows that the superplasticizer (polycarboxylate, melamine resin) and sulphoaluminate cement have good compatibility in fluidity, can effectively reduce the loss of paste fluidity of sulphatealuminium cement. The incorporation of melamine resin superplasticizer can improve compressive strength of sulphoaluminate cement in all ages. Retarding effect of boric acid on sulphoaluminate cement is instability, content is not easy to be controlled, the incorporation of boric acid makes early strength cement of sulphoaluminate significantly lower, D-glucose sodium has remarkable stable effect on the setting time of sulphoaluminate cement, content is easy to control, under its appropriate content, can make slight increase of the strength in all ages. Superfine Calcium carbonate has obvious effection on increase of the strength. Lithium Carbonate and Calcium nitrite have significant effect on increasing the 6h strength of Sulphoaluminate cement, but too much incorporation will lead to the reduction the later strength. Under the multi-component composite, there is significant increase in strength of sulfur Cement of all age, particularly compressive strength of mortar 6h, reached 31.8MPa, and the setting time is moderate.Based on the best ratio for ultra high early strength additive, we have done tests of a super-early-strength grouting material performance. Experiments shows that, the ultra-early-strength grouting material has characteristics of ultra high early strength, 6h compressive strength has reached 37.5MPa, less loss of fluidity through time, expansion is appropriate, no bleeding, no settlement and no isolation.