Research On The Performance Influenced By Composition And Structural Of EPS Lightweight Aggregate Concrete

With the experiments of compressive strength, equal strain static loading, thermalconductivity, dry shrinkage, impermeability, scanning electron microscopy, and the method offinite element analysis, data fitting, the composition and structure impact on performance ofexpanded polystyrene (EPS) lightweight aggregate concrete (PAC) is studied. The results areas follow:high density PAC and low density PAC individually. The formula has following advantages.The key factors, matrix strength and porosity, which affect PAC compressive strength areconsidered in the two formulas. With clear meaning, the formula is applied to strengthprediction or to mix design of PAC. EPS particle size, EPS type, matrix, and other factorswhich could affect the relationship of the concrete compressive strength and the relativedensity can be adjusted by the parameter β1of the formula.With the increase of EPS content, the inflection point of stress–strain curve graduallybecome unclear. Descent stage of the curve goes flattened, and the residual relative stress isimproved. This indicates that the rate of energy release and crack propagation slows downwhen the concrete is after the ultimate stress, and the toughness of PAC is improved with theincrease of EPS content. When the concrete bulk density is less than900kg/m3, pore brittlecollapsed destruction of PAC appears, and the inflection point of stress–strain curvedisappears.Digital model analysis and experimental study show that the important factors that PACcompressive strength decreases rapidly with the increase of EPS dosage are due to thethinning of the pore wall, both ends constraints reduced, and horizontal and vertical bardamaged at the same time besides real pressure area reduction. particle size of1.5~5.0mm is proposed. The formula is applied to EPS dosage determinationaccording to the thermal conductivity of PAC, or to estimate the thermal conductivity of PACaccording to EPS dosage.The results show that the increase of shrinkage of PAC without gravel in pace with theincrease of EPS dosage is partially offset, because the cement dosage decreases with theincrease dosage of EPS, and matrix shrinkage reduces accordingly. The resistance of PAC towater penetration and to chloride penetration decrease with the increase of EPS dosage. Thisis due to interface defects between the EPS and matrix, EPS particles uneven distribution andloose matrix.Through the investigation of the relationship of composition, structure and performanceof PAC, the formulae of thermal conductivity-relative density, and compressive strength-relative density are summarized. PAC mix design method based on the two formulas isproposed. The method can be used to design PAC mixture meeting the requirements ofthermal conductivity, bulk density and compressive strength at the same time.