Research And Development Of Gneiss Powder As Composite Mineral Addition And Application In Concrete

It has huge research and application potential because stone powder as raw materials has a very wide distribution and has a low processing costs.With the rapid development of the infrastructure construction of civil engineering,water conservancy,and transportation industries in recent years,the construction scale and files has rapidly expand after "One Belt and One Road" strategy has been provided.It's obviously that manufactured sand in place of nature sand.In addition,the traditional high-quality mineral admixtures such as fly ash and slag have become increasingly scarce.So it is necessary to study the application of stone powder to prepare green concreteThe article combined with the situation of Shanxi Province aims at use the large amount of gneiss powder produced by producing mechanism sand.Systematically studies the technical features of gneiss powder and the effect of gneiss powder as composite mineral addition on the performance,mechanical properties,long-term performance,and durability of concrete.We proposed reasonable suggestions for the use of gneiss powder as composite mineral addition in concrete,which provided a theoretical basis and technical support for the efficient application of gneiss powder in concrete.The main research contents of this article include:1)Research on the technical characteristics of gneiss powder,including basic performance,fineness,mica content,the effect of the amount on the performance of cement mortar,the study of the adsorption performance of stone powder,and the performance of gneiss powder and limestone powder.The results show that the increase of the content of gneiss powder and the increase of mica content will reduce the performance of the cement mortar,and increase the fineness of the gneiss powder,which increases the filling effect of the micro-aggregate and improves the properties of the cement mortar.2)The results show that composite mineral admixtures can be prepared by combining gneiss powder with fly ash and slag powder.The composite effect of gneiss powder,coal ash and slag powder with the ratio of 6:2:2 is the best.3)The effects of single-doped gneiss powder and gneiss powder as composite mineral addition on the work performance,mechanical properties,long-term durability and durability of concrete were studied.The results show that single-doped gneiss powder has the low performance about concrete than single-doped mineral additions,the dosage of single-doped gneiss powder is recommended to be controlled within 20% of the cementitious material.It is not obvious to improve the performance of concrete through increase the fineness of gneisspowder.The gneiss powder can compound with fly ash or slag powder to improve the workability and mechanical properties of the concrete.The gneiss powder: fly ash: slag powder = 6:2:2 has better performance in improving all aspects of the performance of the concrete.4)The chemically bonded water of cement paste mixed with gneiss powder was studied,as well as the hydration performance of cement hydration products and hydration conditions,and compared with the cement paste mixed with granite powder.When the specific surface area does not differ greatly,the degree of hydration of cement with gneiss powder is higher than that of cement with granite powder.Increase the specific surface area of stone powder and the degree of hydration increase.The small-grained stone powder acts as a dispersive filler,and the large-grained stone powder is a hydration product-dependent scaffold.The inert stone powder acts as a dispersing agent,but excessive stone powder can weaken the concrete performance.