Preparation Of Road Geopolymer And Study On Properties Of Grouting Material

There are some problems such as low bonding strength,high porosity and poor fluidity in the traditional cement-based grouting material.Compared with this,geopolymer has the advantages of high temperature resistance,high early strength,corrosion resistance and low reaction heat.At present,the low mobility and high price of geopolymer limits its promotion in engineering.In view of this,in this paper,fly ash,metakaolin and slag were used to prepare geopolymer as the raw material.The micro and macro properties are analyzed to select the raw material and the mix ratio,so as to improve the fluidity and reduce the price of the polymer under the requirements of mechanical strength.At the same time,in this paper,it has made the grouting material and semi flexible pavement material based on the geopolymer made of metakaolin and fly ash.Specific work and conclusions are as follows:First of all,in order to study the effects of water-binder ratio,modulus of alkali activator,curing time and temperature on geopolymer,in this paper,it adopted some indexes such as mobility,time of coagulation and mechanical strength to evaluate it.The research showed that the ratio of water to binder was the most important factor affecting the fluidity and time of coagulation,and the modulus of alkali activator was the most important factor affecting the mechanical strength of geopolymer.The water binder ratio should be controlled at 0.35 to 0.40.The smaller the modulus of alkali activator was,the stonger the mechanical strength of geopolymer was.With the incorporation of fly ash and slag,the fluidity of the geopolymer basd on metakaolin increased by 4.0%to 10.7%,tht setting time increased by 8.3%to 200%,the compressive strength decreased by 5.0%to 41.0%,and the flexural strength decreased by 4.8%to 24.2%.Secondly,in order to find the evidence of the macroscopical properties of different materials,understand the association mechanism of them and optimize the.formula,the microproperties of the polymer made from five different substrates were studied in this paper.Through the analysis of the molecular structure,phase composition,thermal stability,micromorphology and crystal structure of geopolymer,the gel quantity,absorption exothermic temperature and micropore were observed,and the evidence for the macro properties of different materials and the two relatedmechanisms were obtained.The research showed that the amount of gel generated by the geopolymer which was made of metakaolin was more than others.The amount of the generated gel indicates the degree of polymerization.The thermal stability of the geopolymer made of metakaolin was the strongest.What’s more,the net structure of microspace of it was denser than others and its porosity was the lowest.With the incorporation of fly ash,the amount of gel of geopolymer based on metakaolin was slightly reduced and the thermal stability was declined.However it can improve the fluidity and setting time.So it made the decition that fly ash and metakaolin were used as the raw material to prepare the geopolymer.Thirdly,it adopted some indicators such as fluidity,time of coagulation,bleeding rate,swelling rate and mechanical strength to study the effect of sand binder ratio,the dosage of water reducer and the dosage of expansive agent on the properties of the mortar grouting material which was made of the geopolymer based on metakaolin and fly ash.The research showed that the sand binder ratio was the most important factor affecting the fluidity and mechanical strength of geopolymer grounting material,and the dosage of expansive agent was the most important factor affecting its expansion rate.The larger the sand binder ratio was,the stronger the mechanical strength of geopolymer was and the poorer the fluidity was.The compressive strength of grouting material was 66%higher than that based on the cement,and the flexural strength was 49%higher than that.Lastly,in this paper,based on the matrix asphalt mixture designed with different porosity and different gradation types,and poured into the geopolymer paste and mortar for the preparation of semi flexible pavement material,it studied the mortar filling rate of different porosity and the water stability and high temperature stability of the simi flexible material to evaluation its performance.The research showed,with the increase of designed porosity,the connectivity porosity of the bituminous mixture was increased,the sealing porosity was decreased,and the stability and flow value of the asphalt mixture were decreased.The grouting rate was increased so that the grounting effect was better.The marshall stability of semi flexible pavement material based on geopolymer can be increased by 38%to 91%and dynamic stability can be increased by 40%to 129%,compared with cement base.Above all,in order to solve the problem of low fluidity and high price of geopolymer,the use of low price fly ash to replace the high price metakaolin preparing geopolymer can improve the fluidity and lower the development cost of it.The grouting material and semi flexible asphalt mixture based on geopolymer conform to the standard requirements and the performance are better than the cement based grouting material and semi flexible asphalt mixture.It is suggested to develop cost-effective alkali activators and deepen the research on road performance of geopolymer.