Experimental Study On The Ordinary Dry-mixed Mortar Which Made By The Recycled Sand

With the rapid development of our economy,more and more resources are consumed.The shortage of resources has become an important part of the inhibition of today's social development.At the same time,the structure of building also produce a large number of construction,and the unreasonable stacking of construction waste has caused great damage to society.To ensure the development of society,we need find a way to solve this problems.In recent years,it has some related research of the recycled concrete used recycled coarse aggregate,but for construction waste broken of fine aggregate study is relatively small,the problem of shortage of natural sand resources is not effectively alleviated.In the national natural science foundation of China(51378270),this article has carried on the research work:(1)Using the mechanism of sand and f reclaimed fine aggregate which from waste concrete,and use regeneration of ash powder and fly ash as mineral admixtures to replace cement to the preparation of ordinary dry mixing masonry mortar.The consistency of mortar control to determine within the range of 70~80mm and determine the water consumption,and study the water retention,apparent density,2h loss rate of consistency,compressive strength and frost resistance performance.(2)Using the mechanism of sand and f reclaimed fine aggregate which from waste concrete,and use regeneration of ash powder and fly ash as mineral admixtures to replace cement to the preparation of ordinary dry mixing masonry mortar.The consistency of mortar control to determine within the range of 70~80mm and determine the water consumption,and study the water retention,apparent density,2h loss rate of consistency,compressive strength,14 d tensile adhesive strength,28 d shrinkage and frost resistance performance.(3)To break all waste concrete to made reclaimed sand,and as fine aggregate for mortar preparation,with different dosage of fly ash replacing cement preparation of ordinary dry mixing masonry mortar,the consistency of mortar control to determinewithin the range of 70~80mm and determine the water consumption,and study the water retention,apparent density,2h loss rate of consistency and compressive strength,etc.The research results show that: the bibulous rate of reclaimed sand is significantly larger than natural sand(the bibulous rate of reclaimed sand is about 10%),and aggregate grading is poorer.Using reclaimed sand as fine aggregate to preparation of mortar easy bleeding isolation.As recycled fine aggregate has strong water absorption ability,the 2h loss rate of consistency is not easy to meet the specification requirements.By using three kinds of bonding mortar in dry mixing,Water retention is worse than natural sand.Increase water thickening agent can improve the water retention of mortar.Three kinds of water retention of the slurry from large to small is ? reclaimed sand,? reclaimed,mechanism of sand.Therefore,the use of reclaimed sand preparation of dry mortar must be to control aggregate grading,we should from increasing the amount of cementing material,or adding suitable amount of water thickener to meet the performance requirements for mortar.Considering the cost problem of mortar,in the experiment we used large dosage of fly ash to replace cement used for the preparation of dry mortar,it also can satisfy the use requirement of mortar.Use of reclaimed sand preparation common bonding mortar,in order to best meet the performance requirements for mortar and economic benefit,according to the different strength grade of cement mortar suggest using this proportion:cement sand ratio between 1:3~1:4,fly ash account for 35% ~ 60% of the total cementitious materials,water reducing agent accounted for 0.5% of gelled material,water thickening agent is about 0.3% of the total gelled material,the fineness modulus of sand should be controlled between 2.6~2.8,the powder content is 1%~2% of fine aggregate.