Study On Mix Proportion Of Recycled Fine Aggregate Dry Mixed Masonry Mortar

At present, our country is in the process of municipal facilities and the construction of small cities and towns, faced with natural sand resources shortage and construction waste accumulation problem, looking for alternatives to the sand river has become the hotspot in the field of scientific research institutes, experts and regeneration fine aggregate as a kind of green building materials, the use can not only reduce the exploitation of river sand and alleviate the construction waste accumulation.In this paper, based on a concrete mixing station built a small scientific demonstration line project, the use by the conveying system, crushing, screening, dust removing system composed of abandoned concrete disposal utilization equipment preparation production rate of about 80% of the original recycled fine aggregate, the physical can test results show that the apparent density, bulk density, bulk porosity, water demand ratio, strength of cement mortar, the content of clay and powder content(MB), mass loss rate, crushing index are in line with the national standard II orⅢrecycled fine aggregate.According to the mortar of engineering application to M10 and M7.5 two strength levels of ordinary dry mixed mortar as a benchmark of recycled fine aggregate(original recycled fine aggregate and optimized regeneration fine aggregate) substitution rate of dry mixed masonry mortar performance impact. Test results show that the mortar consistency, consistency loss rate, water retention, setting time and table density are in line with the requirements of the national standard, and the mortar meet the 28 days compressive strength and good shrinkage rate of the premise, the original recycled fine aggregate and optimized regeneration fine aggregate in dry mixed masonry mortar(M10 and M7.5) in the best alternative rate was 25% and 35%, respectively.Through orthogonal test, and to explore the recycled fine aggregate replacement rate, the amount of limestone powder and thickening agent dosage of cellulose ether content respectively of dry mixed mortar(M10 and M7.5) performance. That the original recycled fine aggregate dry mixed masonry mortar(M10) optimum mix cement content is 18%, the amount of limestone powder for 3%, cellulose ether content 0.023%, natural sand content 55.30%, regenerating the original fine aggregate content 23.70%(alternative rate 30%); optimization of recycled fine aggregate dry mixed masonry mortar(M7.5) with the best ratio: the ratio of the amount of cement is 15%, the amount of limestone powder for 6%, cellulose ether content is 0.025%, natural sand content 59.25%, the optimized regeneration fine aggregate 19.75%(substitution rate of 25%). And set up the original recycled fine aggregate and optimized regeneration after fine aggregate replacement rate and the mixing between the 28 day compressive strength of masonry mortar(M10 and M7.5) relationship(y=-0.0112x2+ 0.5918x+15.453 and y=-0.0114x2+0.5047x+12.974), the optimal replacement rate of 30% and 25%, respectively.In this paper, the original recycled fine aggregate produced by the recycled fine aggregate production equipment system is simple and no need to be optimized to deal with(cost saving), the dry mixed masonry mortar(M10) can be prepared. Compared with the optimized recycled fine aggregate, not only the replacement rate has been improved, but also the compressive strength of masonry mortar is higher(5% more). The research results of this paper have reference value for the mix proportion design of recycled fine aggregate dry mixed masonry mortar.