Experiment And Research Of Cut-off Wall Low Elastic Modulus Concrete Properties

Mix proportion and physical and mechanical properties are studied on tow typesof cut-off wall concrete which properties are completely different.--One is highstrength,low elastic modulus and high impermeability concrete suitable to the high dam with deep foundation that can bear high level and stress,and the other is low strength,low elastic modulus and high impermeability concrete suitable to the low level dam and temporary cofferdam.Ideas and crucial technologies are put forward to mix these two types of concrete.In the developing process of concrete cut-off wall,ordinary concrete cut-off wall is prone to rupture because of stress concentration when it endures load.This is mainly because ordinary concrete's strength is relatively low and elastic modulus comparatively high. So it can't deform conformably with the foundation.Therefore,lowering concrete's elastic modulus is critical to solve this problem.To prevent the rupture of concrete cut-off wall ,cut-off wall concrete's properties have to be improved.It is very necessary to develop two new types of concrete cut-off wall material which properties are completely different and that can be applied to different engineering conditions.They are high strength and low elastic modulus concrete and low strength and low elastic modulus concrete.In the developing process of new types of concrete cut-off wall material,the specific requirement to these two types of concrete's properties is not identical because specific engineering conditions are different. High strength and low elastic modulus concrete and low strength and low elastic modulus concrete are all applied to a hydropower station engineering. High strength and low elastic modulus concrete is used in dam and low strength and low elastic modulus concrete is used in cofferdam.To meet construction requirement,the strength development process of high strength and low elastic modulus concrete have to be different from ordinary concrete. Its early strength have to rise quite slowly,7d compressive strength can't exceed 10MPa,and 28d compressive strength can't exceed 25MPa.To endure quite high load,long age strength should be high enough and 90d compressive strength have to reach 45MPa.Meanwhile,to make the reformation conformable in cut-off and dam foundation,90d elastic modulus of cut-off wall concrete can't exceed 3 X 10~4MPa and the ratio of compressive strength to elastic modulus is only 733.To strengthen the impervious effect, low strength and low elastic modulus concrete...