Stress-strain Relation Model And Failure Criterion Of Plastic Concrete Under Compression

Plastic concrete is a composite material lies between normal concrete and clay. With the advantages of nice working performance, low elastic modulus, great deform ability, good permeable performance and low engineering cost, plastic concrete has been widely applied in hydraulic engineering and has great developing potential and application prospect. Wide researches on the engineering application of plastic concrete have been taken since the appearance of plastic concrete, but insufficient in theoretical research.As the main part of the Properties of High-Performance Plastic Concrete Materials and its Cut-off Walls(NO.2010CB635118), this paper is supported by the earlier research project of 973 program. On the basis of the test of plastic concrete under axial and lateral tri-axial compression, the compression behavior of plastic concrete is emphatically studied, and the corresponding calculation models are established. Main research contents are as follows:(1) On the basis of the test of plastic concrete mixture, the influences of water cement ratio, sand ratio, cement content, clay content, bentonite content, type of bentonite on the density, bleeding rate, initial and final setting time, slump, spreading of plastic concrete mixture are studied, the relationship of the ratio of spreading to slump and the working performance of plastic concrete is analyzed, and the The formula of unit water use of plastic concrete is established..(2)On the basis of compression test and splitting tensile test of 396 plastic concrete specimens of 100mm×100mm×100mm and 150mm×150mm×150mm, and the bending test of 90 plastic concrete specimens of 100mm×100mm×400mm, the influences of water cement ratio, sand ratio, cement content, clay content, bentonite content, type of bentonite and curing age (including 540 days long curing age) on the compressive strength, splitting tensile strength and flexural strength of plastic concrete are studied, besides, the size effect of tension-compression ratio and compressive strength, splitting tensile strength of plastic concrete is analyzed, and the matheematical reeation model of compression strength of long curing age and other curing age are put forward.(3)On the basis of uniaxial compressive test of 87 plastic concrete specimens of 150mm×150mm×300mm, the effect of sand ratio, water cement ratio, cement content, clay content, bentonite content, type of sands and bentonite and curving ages on elastic modulus, peak stress, peak strain, energy taken in etc. of plastic concrete under axial compression are systematically studied, the mathematical relation models between elastic modulus,peak strain, stress-strain of contra flexure point, stress and strain of convergent point and peak stress are established, respectively. Then, the strain-stress relationship mathematical model of plastic concrete under axial compression is established.(4) On the basis of test of 36 plastic concrete specimens of 150mm×150mm×150mm under tri-axial compressive load, the influences of sand ratio, water cement ratio, cement content, clay content, bentonite content on tri-axial compressive strength and stress-strain relationship of plastic concrete are comparatively analyzed, and the strain-stress mathematical model of plastic concrete under tri-axial compression is established, besides, the failure criterion equation of octahedral stress space is put forward.