Technical Study On Manufactured Sand Application In Concrete In Tianjin Municipal Engineering

As the rapid development of our economy and the importance to environmental protection, manufactured sand is not satisfy the demand of the engineering .Under this special circumstance ,as one of the material for construction ,manufactured sand is generally used in concrete.In the process of manufactured sand production ,it is inevitable to generate some definite tiny grain which is less than 0.075㎜ and such grain is called– micro fines ,which is also one of the most obvious difference .In contrast to natural sand ,manufactured sand has properties such as :inferior rank ,large thin-mode ,course surface ,many–sided ,pointedness .Manicipal projects require high quality raw material for concretes ,because of high suffer when being used ,the complicated forces suffered ,high strength ,but manufactured sand has such adverse characters,thus it is still in doubts in municipal projects that using manufactured sand in concrete universally .On the basis of disposing municipal engineering by employing manufactured sand ,with the connection between the quality of manufactured sand and natural sand in Tianjin ,dispose mixed sand with favorable rank ,the thin–mode about 2.7 according to definite which satisfy working property of concretes ,and investigates the effects of high ,middle ,and low intensity–rank concretes on emphasis .on working property ,strength ,the mode of elasticity ,and contrac-tility .It indicates through experiments that :high quality mixed sand of manufactured sand and natural sand with utilization of micro fines at about 5-8%,can dispose C50 tank– beam concrete ;with utilization less than 15% can dispose C25 and C30 concretes ;for those low grade concretes ,the utilization has no obvious effects on the strength ,and on the promise of satisfying the working property of concretes ,it has no requests on the utilization of manufactured sand .The application in the municipal engineering ,further validates that :if only we control the utilization of manufactured sand in different intensity ranks of concretes strictly ,it can be applied in the construction of the municipal engineering .