Effect On Basic Mechanical Behavior And Permeability Of Bentonite Plastic Concrete With Bentonite Content Hanging

Based on experimental tests of150specimens, the mechanical behavior, deformation performance and permeability of plastic concrete with bentonite content changing are systematically studied. From these experimental studies, various conclusions can be drawn as follows:(1) On condition that cement content, sand percentage and water-cement ratio remain the same, the standard cubic compressive strength, standard cubic splitting tensile strength and prismatic axial compressive strength of plastic concrete all decrease when bentonite content increases. The basic mechanical strength of plastic concrete decrease rapidly when bentonite percentage is more than0but less than0.375. The basic mechanical strength of plastic concrete, however, on contrary, stay the same or decrease limitly when bentonite percentage goes over0.5but not surpass0.55.(2) The tensile-compressive ratio decreases and the prismatic axial compressive strength to standard cubic compressive strength ratio increases when the compressive strength of plastic concrete is increased.(3) The elastic modulus and bulk modulus of plastic concrete all decrease as bentonite content increases, and all increase as the standard cubic compressive strength is increased. Poisson’s ratio of plastic concrete calculated by elastic modulus and bulk modulus is0.22, which is much more larger than that of ordinary concrete. It means transverse deformation of plastic concrete is more significant when it is compressed.(4) Both plastic concrete and ordinary concrete all have the similar unconfined compressive failure process, but plastic concrete compressive strain-stress curve has initial compressive stage, its peak strain and ultimate strain are larger than that of ordinary concrete. With the increase of bentonite content, plastic concrete compressive stress-strain curve gradually become plump, its peak stress decreases and initial loading stress-strain curve segments tends to be extended, its proportional elastic limit point moves slightly to the right and strain-stress curve nearby the peak point has a tendency to platform.(5) On condition that cement content, sand percentage and water-cement ratio remain the same, as bentonite content increases, peak stress of plastic concrete compressive strain-stress curve decreases and peak strain of that increases. The reduction magnitude of peak stress is less than the growth magnitude of peak strain when bentonite percentage is less than0.375, and the reduction magnitude of peak stress is larger than the growth magnitude of peak strain when bentonite percentage exceeds0.375but is still less than0.5, however, peak stress and peak strain stay the same or decrease limitly when bentonite percentage is between0.5and0.55.(6) On condition that cement content, sand percentage and water-cement ratio remain the same, as bentonite content increases, plastic concrete anti-permeability is enhanced, and its relative permeability coefficient is reduced.