Experimental Study On Mechanical Properties Of Dry-mixing Self-compacting Concrete

Dry-mixing self-compacting concrete (DSCC) is a kind of new concrete which based on free-vibration. It was prepared with the cement, the coarse aggregate and sand of high strength and some cement replacement materials (CRM) that was well-performing concrete with the good performance of fluidity, anti-segregation, tiny inflation and had the better crack resistance. In this paper, an extensive investigation was conducted to evaluate the working-performance and the mechanical behavior DSCC. The safety of DSCC beams designed according to the current valid Code GB50010. The following research work was carried out:(1) The various working-performances of DSCC were investigated according to Guide to Design and Construction of Self-Compacting Concrete (CCES02-2004). The test results indicate that the DSCC of water rates 13% had the better the working performance.(2) The cubical compressive strength and splitting strength characteristics of DSCC with The concrete was prepared with water rates of 12%, 13% and 14% were investigated through a series of experimental work with 330 cubes, mainly covered the effect of varying water rates, the effect of coarse aggregate ratios, the compressive strength and splitting strength development with age and the age factor, the relationship between compressive strength and density. It is shown from the test results that the compressive strength of DSCC generally increases of with increase of coarse aggregate ratio when coarse aggregate ratio is less than 30%. The added water ratio has a considerable influence on the compressive strength of DSCC. It is concluded that growth of earlier period strength of DSCC is more quickly, which has early strength performance.(3) The stress-strain relationship of DSCC with water rates of 12%, 13%, 14% wasstudied experimentally. The axial compressive strength, stress-strain curve, modulus of elasticity, Poisson's ratio and peak strain were evaluated in detail and an approximate stress-strain relation was proposed based on the regression analyses. It is found that the elastic modulus of DSCC is higher while f_c/ f_cu is lower than that of normal concrete.(4) With regard to the hardened properties of DSCC, the aim was to determine whether the commonly used equations for relating the properties of normal concrete, especially the relations between compressive strength, splitting tensile strength, flexural strength and modulus of elasticity, are valid for DSCC. It is found that the interrelationships between the mechanical properties of DSCC are different from those of normal concrete. Therefore, some alternative were proposed for the prediction of the properties of DSCC based on the statistical regression analysis.(5) Based on the hypothesized distribution parameters for the compressive strength, the safety of reinforced dry-mixing self-compacting concrete beams designed according to the current valid code GB50010 were assessed. Moreover, some recommendations for reliability design of DSCC elements are put forward.This may serve as useful background to further research on the possibilities ofdry-mixing self-compacting concrete.