Preparation And Application Research Of Sleeve Grouting Material For Assembly Building

With the progress of industrialization in our country,assembly-style buildings are increasingly concerned by researchers and governments.The assembly-style buildings is a prefabricated building material,and the constructioner in the field then combine these materials.both energy saving,anti-earthquake,insulation,anti-noise,anti-fire and other functions in one of the architectural form.It will become an important direction for the future development of building structure because energy saving,anti-earthquake,insulation,anti-noise,anti-fire and other functions are all in one.The main concern in the fabricated building structure is the connection between the structural nodes and the connection of the longitudinal reinforcement.The reinforced sleeve connection technology is the main connection technology used in the assembled building.With the advancement of technology,the use environment of traditional sleeve grouting material is more and more complex,used in assembly-style buildings exposed more and more problems,such as the strength is not enough,poor durability and so on.In view of the lack of research on sleeve grouting material,this paper has developed a high performance cement-based grouting material with stable performance and excellent quality,hoping to improve the deficiency of traditional grouting material and meet the needs of different engineering program.In this paper,high-grade portland cement is used as cementitious material,fly ash,slag powder and silica fume are selected as mineral admixtures,and river sand is selected as fine aggregate,and high efficiency polycarboxylate water reducing agent is used to solve grouting poor fluidity,the use of plastic expansion agent to compensate for early contraction,the use of UEA expansion agent compensation in the late contraction,the use of early strength agent to achieve the early strength of grouting material,the use of defoamers to eliminate the process of mixing bubbles.The effects of the dosage and type of superplasticizer,early strength agent,expansive agent and defoamer on the performance of grouting material were studied.The orthogonal experiment was used to optimize the ratio of water to cement,mortar to sand ratio,the combination of the way and the replacement rate of mineral admixture to get the best ratio.At the same time,the change rule of grouting material under environmental conditions was studied,and the formula of winter grouting material was developed.The effects of various nano-materials on the performance of grouting materials were studied.The microstructures of grouting materials with nano-materials were analyzed by microscopic analysis method such as SEM,TEM,thermogravimetry and mercury intrusion.Finally,the effects of different sleeve,different size bars and different grouting materials on the grouting joint were studied.The tensile test and fatigue test were used to test the performance of the grouting material.Finally,the best fomula of grout material is compared with the commercial high-strength grouting material for performance and cost.The results of research indicate that:1.Water-reducing agent can effectively improve the flowability of grouting material,the best dosage of water-reducing agent is 1.5%;The best dosage of early-strength agent is 1.5%;The best dosage of the defoamer is 0.1%;The best dosage of plastic expansion agent is 0.02%,The best dosage of UEA expansion agent is 4.98%;2.Choose the combination of water-cement ratio,mortar ratio,mineral admixture combination and dosage for the orthogonal test object.The results of orthogonal test show that the substitution rate of mineral admixtures has the greatest influence on the strength of grouting material for one day,and the combination of mineral admixtures has the greatest influence on the strength of 3 days and 28 days.The water to cement ratio has the greatest influence on the flowability.The optimum results were as follows:water-cement ratio is 0.20,clay ratio is 1.28,mineral admixture substitution rate is 0.17,mineral admixture is fly ash,slag powder and silica fume.The effect of environmental factors on the performance of grouting material was studied.The result shows that the grouting flowability is decreased and the mechanical properties are improved under the condition of summer.Under the winter condition,the grouting material shows a slight increase in flowability and a serious decrease in mechanical properties.3.The effects of nano-silica,nano-calcium carbonate,nano-alumina oxide,carbon nanotubes and graphene oxide on the properties of grouting materials were studied.A kind of fly ash-based in-situ carbon nanotubes is prepared.The results show that the surface-modified nano-silica,fly ash-based in-situ growth carbon nanotubes and graphene oxide can improve the mechanical properties of grouting material with meeting the requirement of enough flowability.The growth of in-situ growth carbon nanotubes and the surface morphology of nano-silica,fly ash-based in-situ growth of carbon nanotubes in grouting material was analyzed by SEM,TEM,thermogravimetry,mercury intrusion.And the change of the pore structure of the grouting material was obtained through the mercury intrusion.4.The experimental results show that different types of sleeves have a great influence on the performance of joints,and different sizes of steel bars do not affect the failure form of joints.Tensile test and fatigue test are used to test the performance of different grouting materials.Finally,the performance comparison and cost accounting are carried out with the commercial high strength grouting material and the optimal formula.The results show that the optimal formula has excellent performance,high cost performance and certain market competitiveness.