Effect Of Particle Size Distribution Of Fly Ash On Mechanical Properties Of Low Temperature Mortar

The particle size distribution of mineral admixture is an important factor affecting the strength of cement mortar.It has good pore structure and hydration performance and can significantly improve the mechanical properties of cement mortar.Fly ash can be used as an excellent mineral admixture,its main component is amorphous SiO2 and Al2O3,which can not only play a good role in the cement mortar to provide micro-aggregate effect and pozzolanic effect,but also solve China's power production environment conflicts between pollution and lack of resources.By changing the particle size distribution of fly ash to improve its own activity,rather than using high-energy ultra-fine grinding technology and high-cost chemical excitation means,the final the pore structure parameters and pore size distributionwereoptimized.Therefore,the study of the particle size distribution of fly ash cement mortar pore structure and mechanical properties is of great significance.Firstly,the influence of particle size distribution of fly ash on the strength of cement mortar was studied.Secondly,the pore size distribution of fly ash-cement mortar was studied from the microstructure,the pore structure,microstructure and hydration characteristics of the impact of further explain the changes in the size distribution of fly ash on the strength of cement mortar;Finally,in order to clarify the correlation between the particle size distribution of fly ash and mechanical properties of cement mortar,multivariate linear regression analysis of the theory of pulverized coal was used,and the correlation coefficient between each particle size distribution and cement mortar strength was studied,the mathematical model the particle size range of fly ash,the strength of cement mortar and the pore structure was established.The effect of fly ash particle size distribution on the strength of cement mortar was studied.The results show that most of the particle size distribution of fly ash can improve the strength of cement mortar under the condition of standard curing or low temperature-10?,and the degree of improvement is different.Among the standard curing conditions,ash distribution was F(1)the compressive and flexural strength of cement mortar to improve the most obvious;and at low temperature-10? curing conditions,Andersen fly ash cement mortar strength to improve the most obvious.The effect of fly ash particle size distribution on the microstructure of cement mortar was studied.The results of pore structure analysis show that,except for the cement mortar with Andersen distribution of fly ash at the standard curing conditions,the porosity of the other distributed cement mortars has been reduced,followed by the increase of the volume of harmless pores.The cement mortar hole was structure significantly improved.The effect of improving particle size distribution of fly ash on the porosity of cement mortar under the condition of-10?curing is less,but the proportion of harmful pores and multi-poisonous pores is obviously decreased,which is beneficial to improve the strength and frost resistance of cement mortar.The SEM results show that the degree of hydration maintained under-10?,and the hydration process is improved with the increase of the ulof the cement mortar under standard curing conditions is higher than that of the cement mortar trafine fly ash content of the fly ash.The results of micromorphology analysis showed that the degree of internal hydration of cement mortar under standard curing conditions was higher than that of cement mortar under-10?,and water was increased with the appropriate increase of fly ash particle size distribution process.Hydration performance analysis results show that the change of particle size distribution of fly ash can increase the hydration exothermic rate and the total amount of exothermic heat of cement mortar.With the increase of the content of small particle of fly ash,the hydration of cement mortar curing at the early stage was improved.The internal pore structure and hydration exothermic properties of cement mortar affect its strength.Based on the theory of gray multiple linear regression analysis,the correlation between the particle size distribution of fly ash and the strength of cement mortar and the mathematical model for establishing the size range of fly ash,cement mortar strength and pore structure were studied.The results show that the content of fly ash in the four granularity ranges of 3?5?m,5?8?m,8?10?m and 10?15?m has a good correlation with the strength of cement mortar,and the strength was greatly improved.According to the standard curing conditions of the fly ash particle size interval,the strength of cement mortar and pore structure parameters,the mathematical model was established to predict the strength of cement mortar under low temperature-10 ? curing conditions,the prediction effect is better.