Study On Physical And Mechanical Performance Of Rapid Repair Material

Portland rapid repair material have advantages of short setting time and early strength,is widely used in pavement construction engineering,but it ofen use sulphoaluminate cement and phosphate cement as the matrix material of rapid repair material,their shortcoming are high cost,bad water resistance and poor durability.,the properties of ordinary silicate cementitious material have slow coagulation and low early strength.Based on the research and application status of repair materials,this paper studies the properties of portland rapid repair materials,which can be used in construction.Experimental study on silicate cementing material specific surface area size,gypsum,silica fume,defoaming agent and early strength agent content and water cement ratio on the impact of Portland rapid repair setting time,fluidity,compressive strength and shrinkage of materials,and the analysis of the phase composition of hydration products and microstructure.The effects of various factors on the properties of rapid repair materials were studied with the specific surface area of 450 m2/kg and 550 m2/kg respectively:The best proportion of quick repair material is:the specific surface area is 550 m2/kg,the water to binder ratio is 0.15,the gypsum content is 0.75%,the content of silica fume is 5%and the content of sodium aluminate is 0.5%.At this time,the initial setting time of mortar is 17 min;4 h flexural strength reached 2.1 MPa,the compressive strength reached 16.1 MPa,8 h flexural strength reached 3.2 MPa,the compressive strength reached 36.1 MPa;the shrinkage tends to be stable at the age of 3d,and is 0.125%.The surface area is 350 m2/kg,450 m2/kg and 550 m2/kg silicate cementitious materials,with the specific surface area becomes larger,the coagulation time is shortened,the flow degree decreases,compressive strength increases,shrinkage increases.With the content of gypsum(0%-0.85%)increases,the setting time is gradually extended,the fluidity decreased after increasing,compressive strength increased,shrinkage decreased,content to meet the construction requirements of 0.5%?0.8%;with the content of silica fume(0%?20%)increases,the setting time first decreases and then increases,the fluidity decreased after increasing,the compressive strength increases first and then decreases,shrinkage increases,when the amount is 5%,repair materials(with 550 m2/kg as the substrate)the compressive strength reached the maximum,4 h compressive strength was 11.54 MPa,1 d compressive strength was 73.68 MPa;with the increase of water binder ratio(0.15?0.19),portland rapid repair of condensation the material time gradually extended,the fluidity increases,the compressive strength decreases,shrinkage increases.With the content of defoaming agent(0%?0.05%)increases,the compressive strength of the patch material becomes larger then smaller,shrinkage decreases.With the content of sodium sulfate(0.0%-2.0%)increases,repair materials slightly shorter setting time,fluidity decreases,the compressive strength increased first and then decreased,when the amount is 1%the compressive strength reaches the maximum;with the increase of content of sodium aluminum silicate,rapid repair material setting time is shortened,the fluidity becomes small the compressive strength increases first and then decreases,shrinkage has no obvious change,when the amount is 0.5%the compressive strength reached the maximumThe microstructure of rapid repair material show that hydration ettringite and C-S-H gel and Ca(OH)2 in hydration products,portland rapid repair material has the best mechanical properties.The specific surface area increases,hydration products increase;gypsum,silica fume and early strength agent can promote portland rapid repair material hydration,adjust the water to glue ratio and defoaming agent content can change the structure of hydration products.