Study Of Precast Concrete Structure Sleeve Grouting Material

Precast concrete structure sleeve grouting material is made with the strictly repice of cement,fine aggregate,chemical admixtures,etc.After adding water and mixing,it has the characteristics of high liquidity,not bleeding,high early strength,high strength,micro expansion,high durability and can adapt to different construction environment,etc.Its main application in precast concrete structure,play the role of connecting steel bar and sleeve,it is the main structure material to realize the safe and reliable connection between precast concrete structural members.Compared with the traditional grouting material,precast concrete structure sleeve grouting material has a higher early strength,high post strength and better filling ability.ensure steel bar and sleeve safe and reliable connection,and has a good quality stability.In order to meet the development needs of precast concrete structure,this paper for the research of precast concrete structure sleeve grouting material.First of all,this paper break the traditional idea of using a single cement in grouting material,by using composite cement system of ordinary Portland cement and sulfate aluminate cement as gelling material.The results show that composite cement system can obviously improve the early strength and post strength of grouting materials,but can reduce the setting time of grouting material;when the replacement rate of sulphur aluminate cement is 10%,the composite cement system grouting material has the highest compressive strength and flexural strength,micro structure of hydration product more dense.Secondly,the influence of the composition material on grouting material is studied.The results show that single doped silica fume within 8%can increase the compressive strength of grouting material,and within 5%can improve the fluidity of grouting material;when only mixed superfine fly ash within 5%can improve the Id and 3d strength of the grouting material,with superfine fly ash content increased,the 28d strength and fluidity of grouting materials increased;the strength and fluidity of grouting materials can be improved by the compound silica fume and superfine fly ash.Sodium gluconate and hydroxyl methyl propyl cellulose ether can extend the initial setting and final setting time of grouting material,and at the same time have auxiliary plasticizing effect,the optimal dosage of sodium gluconate is 0.08%,the optimal dosage of hydroxyl methyl propyl cellulose ether is 0.02%,water retention is 90.4%,with the dosage increase,the fluidity and strength decrease.When the temperature is reduced,the early strength of grouting material decrease,the grouting material needs to compound with the early strength agent(LiC03),the optimal dosage is 0.1%,LiC03 can reduce the 28d strength.At the same time,the close packed model Dinger-Funk equation is used to optimize the aggregate gradation,T300 test is used to analyze the working performance of grouting material more comprehensive.The results show that optimization of aggregate gradation by Dinger-Funk equation,1d strength of grouting material increased by 25%,3d and 28d strength changed little,when the particle distribution modulus n=0.36,the aggregate gradation is the most closely packed state.The T300 test can measure the viscosity of plastic paste,T300 between 9 and 11 seconds,the workability of slurry is perfect,less than the range,prone to segregation and bleeding,greater than the range,the viscosity of slurry increased.Silica fume can increase the viscosity of slurry,superfine fly ash can reduce the viscosity of the slurry.In the end of this paper,the durability of optimal recipe is studied and the tensile test of the sleeve is carried out.The results show that the electric flux of grouting material with single doped 15%superfine fly ash and single doped 5%silica fume are reduced by 49.9%and 37.4%,when mixed,electric flux reduced by 68.5%.3.5%NaCl solution can aggravate the quality loss of grouting material after freezing and thawing,the mass loss of the grouting material in the 5.0%Na2SO4 solution is decreased,and the relative dynamic elastic modulus is slightly higher than that in water,in the composite solution of 5.0%Na2SO4 and 3.5%NaCl,the surface erosion is the main damage,while the decrease of relative dynamic elastic modulus is not obvious.The vertical expansion rate of grouting material meet specification requirements,in drying shrinkage tests,along with the prolonged,grouting materials expanded after contract first,in the autogenous shrinkage test,the specimen is always in the state of expansion.Steel sleeve specimen damage are all steel yielded after fracturing,the load-displacement curve of reinforcement sleeve member is similar to steel bar,the yield strength and ultimate tensile strength of the reinforcement sleeve member is consistent with that of the steel bar.