Performance Of Low Quality Fly Ash Lignin Fiber Composite Plastering Mortar

With the rapid development of contemporary architecture,the plastering mortar workability,adhesive property and crack resistance requirements are getting higher and higher.The different kinds of admixtures are mixed in plastering mortar have been explored and researched,has become the hot spot of the research trends.In Ningxia area,a large number of low quality fly ash can not be used,which is piled up in the ash field,which is used to occupy the site and pollute the environment.How to effectively utilize low quality fly ash has become a hot research topic.Study on application of low quality fly ash in concrete has made gratifying achievements,low quality fly ash can improve the tensile and flexural properties of concrete but low quality fly ash for little related research of plastering mortar,plastering mortar without reinforcement and the strength requirements of low,low quality fly ash will be used in plastering mortar,to meet the requirements of strength,this paper puts forward the application research of low quality fly ash into plaster mortar,in order to provide reference for the effective utilization of low quality fly ash to improve the performance of the plastering mortar.In this paper,the grade M15 mortar is used as the research object,water binder ratio,replacement rate of low quality fly ash,super-mixing ratio of low quality fly ash,and lignin fiber content as factors,characteristics of low quality fly ash and lignin fiber plastering mortar were explored by orthogonal test.Experimental results results show that:(1)For the workability of mortar plastering,replacement rate of low quality fly ash,super-mixing ratio of low quality fly ash,and lignin fiber content can significantly improve the mortar workability;replacement rate of low quality fly ash and super-mixing ratio of low quality fly ash can increase the fluidity of mortar,lignin fiber content can improve the water retention property of mortar.(2)For the mechanical properties of mortar plastering,replacement rate of low quality fly ash has a negative effect on the strength of mortar,which has a great influence on the compressive strength and tensile bond strength,but has little effect on the tensile strength;The strength of mortar can be improved by adding low quality fly ash,positive effect of suitable excessive addition on strength can compensation,even more than the loss caused by equivalent replacement about compressive strength and tensile strength;Lignin fiber can improve the strength of plastering mortar,the bond strength and tensile strength of the enhancement effect was obvious.(3)For the drying shrinkage of mortar plastering,replacement rate of low quality fly ash or addition of lignin can effectively restrain the drying shrinkage of mortar,super addition of low quality fly ash slightly enlarges the shrinkage of mortar increase,however,the influence is not significant.(4)The least square method was used to build multiple nonlinear regression model for the workability,mechanical properties and drying shrinkage of plastering mortar,the significant of regression model is high,and the correlation is good.The results have important practical significance for the comprehensive utilization of inferior fly ash in Ningxia area,and improvement of plastering mortar and workability,adhesion and crack resistance.