The Influence Of Light-weight Aggregates On The Mechanical Properties Of Self-Compacting Concrete

It becomes a hotspot nowdays for the researchers to develop the new kinds of civil-engineering materials with both high static and dynamic mechanical performances because of the human activities and nature disasters like earthquake. Based on the present researches at home and abroad, the properties of light-weight aggregates and self-compacting concrete, this paper studied the workability, the compressive strength, the dynamic elastic modulus, the fundamental frequency of vibration, the dynamic shear modulus, the dynamic poisson’s ratio and the damping ratio of self-compaction concrete with different aggregate systems (ceramsites, rubber particles, EPS particals, the double-doped and the multi-doped of that tree kinds of light-weight aggregates). Meanwhile, in order to give a technical support for the researches of new cement based materials with good workability and dynamic performance, this paper also analyzed the correlations between the compressive strength reduction rate and the volume fraction of light-weight aggregates, the dynamic elastic modulus reduction rate and the volume fraction of light-weight aggregates, the dynamic elastic modulus and the compressive strength, the damping ratio and the compressive strength.The results of the experiments and calculations showed that,(1) the ceramsites, rubber particals and EPS particals have different influences on the workability of self-compacting concrete. With the help of water reducing agent and thickening agent, it can keep the fresh self-compacting concrete, which are with double-doped and multi-doped light-weight aggregates, a good work performance.(2) At the age of28days, the compressive stregth reduction rates of self-compacting concrete with light-weight aggregates have a positive linear correlation with the volume fraction of light-weight aggregates. Within the same volume fraction of light-weight aggregates, the self-compacting concrete with rubber particals and those with EPS particals have a similar effect on the reduction of compressive strength, while the self-compacting concrete with ceramsites have a much less reduction of the compressive strength. The multi-doped light-weight self-compaction concrete have a higher compressive strength compared to the concrete with other kinds of aggregate systems.(3) With the increase of the light-weight volume fraction, the dynamic elastic modulus, vibrational frequency and shear modulus of self-compacting concrete with different light-weight aggregate systems decrease. It’s verified that there is a positive linear correlation between the reduction of dynamic elastic modulus and the light aggregate volume fraction. Close linear correlation between compressive strength and dynamic elastic modulus was also revealed in self-compacting concrete with light aggregate while the differet light aggregate systems have different influences on the decrease of dynamic elastic modulus of concrete.(4) Poisson ratio of self-compacting concrete with light aggregates was irrelevant to age and volume fracion of light aggregates, and remained within the normal fluctuation range of0.25±0.02.(5) Damping ratios of self-compacting concrete drastically reduced with the increasing number of vibration cycles within the first40cycles, and showed stable tendency until the40th vibration cycle. Damping ratios of self-compacting concrete with light aggregate at28d were apparently smaller than that at7d. At the same age, damping ratios of self-compacting concrete varied with the light aggregate systems. Damping ratio of self-compacting concrete decreased with the increase of compressive strength. However, damping ratio and compressive strength were poorly linear correlated.