Study On The Performance Of The Low Temperature Sleeve Grouting Material

Assembly building has entered a period of rapid development,In order to ensure the integrity of the components and the strength of the connection,It's necessary to connect prefabricated with cementitious grout for coupler.Low temperature cementitious grout for coupler is suitable for using in hard climates.Its main purpose is to accelerate the speed of cement hydration in low temperature environment.A series of experiments were conducted on the composite cement as a gel material.What's more,the experiment shows that the ratio of glue to sand is 1.0,and the water to binder ratio is about 0.28.On the basis of the above ratio,the mineral admixtures were tested by single doping and orthogonal test.The best effect of silica fume is 4 %.The test results showed that the dosage of gypsum was 12 %.The appropriate amount of gypsum is beneficial to reduce the shrinkage of cement and have the effect of micro expansion.Orthogonal test of gypsum with tartaric acid and lithium carbonate.The optimal combination was as follows: gypsum content: 12 %,tartaric acid content: 0.16 %,lithium carbonate content: 0.12 %.Sodium nitrate,calcium formate and sodium sulfate were used as antifreeze,they were used for single doping test and orthogonal test.Through orthogonal test,it is found that the influence of sodium formate and sodium sulfate on the convective motion is very large,which can't meet the requirements.At last,the sodium nitrate with the smallest influence of convective motion is chosen as the antifreeze,and the optimum dosage is 0.4 %.The ratio of low temperature cementitious grout for coupler : The portland cement(PO 52.5)accounted for 70 % of composite cement,High alumina cement accounts for 20 % of composite cement and sulphoaluminate cement accounts for about 10% of composite cement;Silica fume accounted for 4 % of the cementitious material;gypsum content accounted for about 12 % of cementitious materials;The ratio of binder to sand is 1:1,Water accounts for 28 % of cementitious materials;The content of tartaric acid was 0.16 %,the content of lithium carbonate was 0.16 %,and the content of sodium nitrate was 0.4 %.According to the actual requirements,two kinds of low temperature cementitious grout for coupler P-1 and P-2 were developed.The vertical expansion rate?temperature effect? long-term strength and chloride ion content were tested.The experimental results show that the performance can meet the relevant standards.The successful development of the low temperature cementitious grout for coupler makes it possible to construct the steel sleeve grouting in winter and cold area,which greatly simplifies the construction process and saves the cost.