Study On The Influence Of Mineral Admixtures On The Performance Of Machine-made Sand Dry-mixed Mortar

Dry-mixed sand mortar equivalence point,green ring equivalence point,revisited purpose-built tech business.Mineral admixtures have gradually become the focus of research in the field of cement-based materials in the process of mortar commercialization.Since industrial solid waste has good"morphological effect","micro-aggregate filling effect"and a certain"volcanic ash effect"potential,if it is used as a mineral admixture to replace part of cement,it can promote low-cost,high-performance dry mixing Research and development of mortar.This paper selects sulfur-fixing ash powder,steel slag powder,and ultra-fine limestone powder as the admixture of machine-made sand dry-mixed mortar.Through comparative experiments and orthogonal experiments,the three mineral admixtures are studied for single-mixing and compound-mixing against machine-made sand dry-mixing.Affect macroscopic properties of mortar and effect of mineral admixture micro cementing system using XRD and SEM-EDS detection methods,results showed that:Adding CFBCA alone can significantly improve the water retention and pore structure of the mortar,increase the strength of the mortar in the later stage,enhance the water resistance of the mortar,and reduce the loss of mortar consistency to a certain extent,increase the opening time of the mortar,and facilitate construction.The preferred dosage of single blending is 40wt%,and the 28d compressive strength of the mortar is increased by 31.07%;Steel slag powder as dry mixing mortar mixture improves the flowability of the mortar,reduce the water requirement of the mortar,increasing the water retention of the mortar,to extend the curing time,enhance the uniformity of the pore structure of the mortar,It increases the strength of the mortar in the average pore size,and the later stage of the pores.The single mixing ratio is 15wt%,and the 28d compressive strength of the mortar increases by 10.73%;a small amount of limestone ultrafine powder can improve Mortar fluidity,water retention,mortar pore structure and mortar strength,but as the dosage increases,the construction performance and mechanical properties of the mortar are significantly reduced,and the preferred dosage is 10wt%.The orthogonal test was conducted to study the influence of the compound mineral admixture on the performance of the machine-made sand dry-mixed mortar.The results showed that the best compounding combination was:the content of sulfur-fixed ash slag powder was 33.3wt%,and the content of steel slag powder was 16.7wt%;At the same time,it was found that effective compounding can increase the content of low-activity admixtures and reduce the production cost of mortars while ensuring the strength requirements of the mortar.According to XRD and SEM-EDS technical analysis,the mineral admixture-cement cementing system is similar to the cement hydration product,but the structure is different.The sulfur-fixing ash powder contains Ca O and anhydrite,which is beneficial to promote the formation of AFt,CH and CSH gels and improve the compactness of the microstructure;obvious defects and hydration reaction marks appear on the surface of steel slag particles;superfine limestone-cement system Monocarbon hydrated calcium aluminate appears in the hydration product,that is,ultrafine limestone powder with a specific surface area of 550cm~2/g has hydration activity,which promotes the early mechanical properties of the cementitious material..