Study On Character Of Mineral Powder Produced In The Production Process Of Machine-made Sand And It’s Application In Concrete

In order to make full use of the mineral powder produced in the production process of machine-made sand,the mineral powder replace some cement in concrete has become an inevitable trend.In this paper based on the existing four mineral powder(the Limestone Flour,the Granite Powder,the Iron Ore Tailing,the Recycled Aggregate Powder)in Xi’an area as the research object,the basic properties of powders is analysed and the effect of powder content to the cement paste rheological properties and mortar liquidity and strength are syudied.Taking the Granite Powder as an example,the impact of the Granite Powder on the concrete is researched.Main contents and results are shown as follows:(1)The chemical composition and mineral composition and each performance index of the the four mineral powder in Xi’an area have been tasted.It shows that the Granite Powder,Iron Ore Tailing,and Recycled Aggregate Powder are Silica powder.Particle morphology experiment shows that the surface of the Limestone flour,Granite powder and Iron ore tailing are smooth,but the surface of the Recycled Aggregate Powder is uneven.Contact Angle test shows that Parent rocks are hydrophilic substances,the water absorption of bricks is strongest and that of limestone is the weakest.(2)Study on the basic properties of powder shows fine powder as admixture has contribution on Mortar strength.(3)The Zeta potential of “Mineral powder-Water reducer” system,rheological property of cement paste and the liquidity and strength of mortar are studied.Results of disturbance value show that the Limestone Flour and the Iron Ore Tailing have better adaptability with PCA,the Recycled Aggregate Powder is just the opposite.The workability keep significantly superiority in cement paste and mortar containing Limestone flour,Granite powder or Iron ore tailing by adding polycarboxylic superplasticizer(PCA)compared with naphthalene superplasticizer(FDN);when the mass fraction of those three powder in cement paste and mortar within 18%,the performance of cement paste and mortar is best.When the mass fraction of Recycled aggregate powder in cement paste and mortar with FDN less then 12%,the performance of cement paste and mortar is best.(4)Study on Workability,Strength and Early shrinkage of concrete with Limestone Flour.Results show that proper amount of the Limestone flour has a little effect on workability of concrete and the Limestone Flour can improve early strength of concrete.When the mass fraction of Limestone flour in concrete is 6% or 18%,7d early shrinkage of concrete is 150% of that without powder and it fit the standard demand.