Autoclaved Concrete Mix Design Study Based On The Surplus Coefficient Of Volume

Concrete mix has always been a significant issue in concrete engineering. Whether it be on the mix proportion design of ordinary concrete, or mix proportion design of high-performance concrete, or mix proportion design of speciale concrete, or the optimized mix design, previous results give us very good guide and reference and provide a good basis for the better mix design. Through the study on the mix proportion design of our predecessors, mechanical properties and durability of high performance concrete and other aspects of the changes became more and more clear. However, due to the variety of building materials and a large regional and time complexity of concrete composition, many mix designs do not completely meet modern concrete mix design requirements, so research on mix proportion design still has a very strong value now.This article study of mix proportion design method autoclaved concrete--autoclaved concrete mix design study based on the surplus coefficient of volume, its specific steps are:determine the aggregate amount, the surplus coefficient of volume of stone is1, the surplus coefficient of volume of sand is k1, use formula to find out the amount of sand and stone; determine amount of cementitious materials, use formula to find out the amount of cementitious materials based on the surplus coefficient of volume of cementitious materials k2; determine the relationship between strength of concrete and the proportion between admixture and cement k3, determine admixture dosage; determine the additive dosage and water-Binder ratio.In this paper, limestone crushed stone test blocks and crushed pebble test blocks had reached maximum intensity when k1is1.05. To limestone crushed stone test blocks, with the increasing of k2, density, compressive strength, shear strength gradually increased, it was the maximum shear strength when k2was2.5, and density, compressive strength was maximum value when k2was2.8. To crushed pebble test blocks, with the increasing of k2, test blocks densities were essentially the same and its compressive strength was increased and stabilized, and reached the maximum value when k2was2.8. The strength of concrete is the maximum value when k3was1/3, so k3is about1/3.It was basically no effect by the mixed of different water reducing agent for strength of limestone crushed stone autoclaved concrete. Using silicon fume as admixture, the change of mixing amount of silicon fume did not influence density, but with the increasing of mixing amount of silicon fume, flexural strength and compressive strength of test block was declining trend, and test blocks became parched, and the granular becoming clear. Water-Binder ratio has no effect on the density of the concrete. Using polycarboxylate water-reducer, flexural strength and compressive strength of concrete reached maximum value at0.27water-binder ratio. Using FDN water-reducer, flexural strength and compressive strength of concrete reached maximum value at0.29water-binder ratio.When aggregate was limestone crushed stone, the maximum value of compressive strength of autoclaved concrete test block was between80MPa and100MPa,and when aggregate was crushed pebble,the maximum value of compressive strength of autoclaved concrete test block could be more than100MPa or120MPa.