Mix Proportion Optimization Design Research Of Green Ecological Concrete

Green ecological concrete is a kind of new type concrete material, which owns the performance between ordinary concrete and cultivated soil, and can adjust the ecological balance, landscape the environment, achieve the coordination between human and nature; it also meets the inevitable requirement of building a resource-saving and environment-friendly society in China. Based on Materials Science, Ecology, Botany and other basic theory science, drawing on the idea of the mix proportion design method of ordinary concrete, taking rheological parameter optimization of cement-based cementitious materials paste as the point cut, the article proceeds the effect that the factors such as water-cement ratio, the material composition and content, and superplasticizer have on performance of green ecological concrete in depth. Using MATLAB programming, the relationship between raw materials and properties of green ecological concrete has established; then the mix proportion of green ecological concrete has been optimized by the sequential quadratic programming and optimization toolbox of MATLAB.The main conclusions are as follows:(l)When the dosage of single mixing fly ash (FA) ranges from 20% to 40%, as the shear rate increases, the paste appears shear thickening at first and shear thinning later, as the FA dosage increases, the degree of shear thickening and shear thinning reduce first and increase later; When the dosage of single mixing slag(SG) ranges from 20% to 40%, as the shear rate increases, the paste appears shear thinning at first and shear thickening later, and as the SG dosage increases, the degree of shear thinning increases gradually while the degree of shear thickening reduces gradually.(2) When the dosage of double mixing FA and SG remain 30% and double mixed ratio ranges from 1:2 to 2:1, as the shear rate increases, as the rheological curves are similarly to the curves while single mixing fly ash, the pastes appear shear thickening at first and shear thinning later; and that indicates FA has a larger effect on the rheological property of cement-based paste than SG. But different from single mixing FA, the degree of shear thickening and shear thinning of double mixing FA&SG pastes reduce gradually as the FA dosage increases and the SG dosage reduces.(3) Based on the Herschel-Bulkley model, under the condition of the water-cement ratio of 0.29, admixture combination that makes the rheological properties of cement-based cementitious material paste meet the requirements of that of green ecological concrete(ie, yield stress is relatively small and moderate viscosity) were optimized:the mixing ratio of FA&SG was 1:1 or 2:1.(4) According to Taylor series formula, the relationship between performance (compressive strength and porosity) and the material (water-cement ratio, the composition and amount of cementitious materials, the super-plasticizer dosage) of green ecological concrete have been established when the range of coarse aggregate size is 16.0～19.Omm or 19.0-26.5mm.(5) According to the sequential quadratic programming method, based on MATLAB toolbox, targeted the 28d compressive strength and porosity of green ecological concrete, within the optimal ranges of raw materials dosage, the optimum mix proportion of green ecological concrete has obtained when the range of coarse aggregate is 16.0-19.0mm or 19.0～26.5.(6)With effective porosity of 27.1%,28d compressive strength of 9.1MPa, coarse aggregate of 16.0～19.0mm,Bermuda grass is seeded on the green ecological concrete of optimization; That bermuda grass grows well indicates green ecological concrete has been produced successfully.