Study On Mechanical Properties And Freeze-thaw Resistance Of Polymer Mortar With Silica Fume And Tailing Sand

Polymer mortar is a kind of mortar material based on the aluminosilicate mineral materials through the alkali activation effect of the alkali activator,after a series of depolymerization and polycondensation reactions,the amorphous sodium aluminum silicate gel is formed.It has green environmental protection and other characteristics,which can replace cement mortar for hole filing and window sill,balcony plastering and other projects.In order to realize the reuse of industrial wastes of silica fume and tailing sand,this research uses sodium silicate and sodium hydroxide as alkali stimulants,slag and metakaolin as mineral materials,and introduces silica fume to replace mineral materials and tailing sand replace river sand of same quality.Explores the preparation process of M20 polymer mortar with good test performance.Mainly studied the following contents of polymer mortar mixed with silica fume and tailing sand:(1)Use single factor method on the main factors.It shows that: 1)When the proportion of silica fume increases from 0% to 10%,the strength of the polymer mortar first increases and then decreases.The performance is better at 5%,and silica fume can improve the early compressive strength.2)Single factor study of slag: In metakaolin,the larger the proportion of slag,the higher the compressive strength and the lower the flexural strength.3)When the modulus of sodium silicate increases from 1.3 to 1.6,the strength first increases and then decreases,and the performance is better at 1.5.4)When the proportion of tailing sand increases from 0% to 30%,the strength first increases and then decreases,and the performance is better at20%.Using the tailing sand,the compressive strength of the later period is improved obviously.(2)In the orthogonal test of four factors and three levels,the order of the degree of influence of the main factors on the strength of polymer mortar analyzed by the range variance method is: sodium silicate modulus> tailing sand proportion> silica fume proportion> slag:metakaolin,However,the best mix proportion in the horizontal range is: 1.5 sodium silicate modulus,20% tailing sand proportion,5% silica fume proportion,7:3 slag: metakaolin.According to this,the 28 d compressive strength of the polymer mortar reached 26.5MPa,which was 9.1% higher than the comparative cement mortar,and the 28 d flexural strength reached4.9MPa,which was 11.4% higher than the comparative cement mortar.(3)In the freeze-thaw resistance test,the sodium silicate modulus was increased from 1.3to 1.5,and the strength loss rate was reduced by 5.7%;the proportion of silica fume was increased from 0% to 5%,and the strength loss rate was reduced by 0.6%;the proportion of tailing sand was reduced from 0 % Is increased to 20%,and the strength loss rate is reduced by1.1%.Both silica fume and tailing sand can improve the freeze-thaw resistance,and the polymer mortar meets the freeze-thaw resistance index required by the specification.(4)The phase composition is studied by XRD,and the study shows that the appropriate amount of silica fume and tailing sand can consume more unreacted mineral materials,improve the formation efficiency of amorphous sodium aluminum silicate gel,and improve the strength and freeze-thaw resistance.The analysis of the formation mechanism of polymer mortar is: the mineral materials are stimulated by alkali to continuously dissolve the silico-aluminum material,the aluminosilicate undergoes depolymerization reaction in an alkaline environment,and the resulting product is aluminosilicate oligomer,which is in polycondensation.In the reaction,the aluminosilicate oligomers were polycondensed into an amorphous sodium aluminosilicate gel.This kind of product has a great increase in strength and freeze-thaw resistance.The polymer mortar formed by mixing fine aggregates with unreacted quartz and other crystalline materials of the mineral materials has higher strength and good freeze-thawa resistance.Through the research of this article,it is found that silica fume and tailing sand can improve the strength and freeze-thaw resistance of polymer mortar.The prepared polymer mortar has better strength and durability,which provides a good opportunity for the promotion of polymer mortar in engineering as reference.