Research On The Basic Mechanic Performance And Deformability Of Plastic Concrete

For a quite long time, stiff concrete has been the main cutoff-wall material. However, with the long-term application, it has been found that the characters of stiff concrete such as higher elastic modulus, greater rigidity, poorer deformability, higher cost, longer construction period affect its application effect as cut-off wall material. Plastic concrete is a soft material which is normal concrete added clay or bentonite, or both. When it is essential, some admixture or additive materials would also be added. Plastic concrete has the advantages of lower strength, lower elastic modulus, greater deformability, nice working performance, well conformability with the surrounding foundation or adjacent rock. So it is an ideal cutoff-wall material. Nowadays, plastic concrete has been applied to large dam engineering, cofferdam engineering, large dam repaired engineering, foundation engineering, and so on. Although both here and abroad have carried out many researches on plastic concrete, systematic research on basic performance and further research on testing methods of stress-strain relationship is still lack. Therefore, this dissertation is on the bases of the item of ZhaiKou Reservoir reinforced, and primary investigates are the basic performance and the testing methods of stress-strain relationship of plastic concrete. Main research subjects and results obtained are as follows:1. Through testing the work performance, compressive strength, splitting tensile strength, shear properties, permeability of seven mixture of plastic concrete, the effect of the experimental condition, water cement ratio, sand ratio, cement content, clay content, bentonite content, bentonite of different types, aggregate of different types, fly ash and admixture on basic mechania performance are studied;2. The stress-strain curves of 63 plastic concrete speciments of 150mm×150mm×150mm are tested in three loading speeds. The three loading speeds are 0.05MPa/s, 0.10MPa/s, 0.15MPa/s, then, the effect rule of loading speeds on plactic concrete and deformation is analyzed. The obvious area of the loading speed effect on strength and deformation of plactic concrete of different strength is put forward;3. The axial compressive stress-strain curves of 21 plastic concrete speciments of 150mm×150mm×300mm are tested, then, the curves are classiflied and segmented analyzed; what's more, the strain-stress mathematical relation model of plastic concrete is put forward;4. By means of analysis on experimental results, the calculating method of elastic modulus is discussed, then a more scientific and befitting calculating method of the elastic modulus of plastic concrete has been gained. The effect of ages on elastic modulus and elastic modulus-strength ratio is analyzed;5. Through testing stress-strain curves of plastic concrete in different measuring distance, the influence mechanism of measuring distance on elastic modulus is analyzed. By means of comparative analysis, it is suggested that the suitable measuring distance of the elastic modulus of plastic concrete should be whole length of plastic concrete speciments.