单掺黏土的塑性混凝土配合比试验研究

Experimental study on mix proportion of plastic concrete with clay

针对设计方提供的塑性混凝土的性能要求,采用工程类比法,设计了22组配合比进行塑性混凝土力学性能试验,以立方体抗压强度、弹性模量、三轴抗压强度和渗透系数为评价指标,着重研究了单掺黏土条件下塑性混凝土配合比的设计及原材料、龄期对塑性混凝土性能的影响,结果表明单掺黏土的配合比方案能够满足工程要求。当黏土含量在一定范围内(小于80 kg/m^3)时,塑性混凝土强度随着黏土含量增加而减小,弹性模量随着黏土含量增加而增大。当黏土含量高于80 kg/m^3后,黏土含量继续增加,塑性混凝土强度变化不明显,弹性模量在一定范围内波动;塑性混凝土强度和弹性模量与水泥含量呈明显正相关关系,与膨润土含量呈负相关关系;在三轴围压条件下,两组优选配合比90 d龄期相对28 d龄期抗压强度平均增长19%;90 d龄期渗透系数相对28 d龄期渗透系数有所减小。

Experimental tests on plastic concrete are conducted in this study by using engineering analogy method and comparing 22 sets of different mixing proportion under its performance requirements provided by the designer.We focus on the concrete’s design schemes of single clay mixing and the influence of raw materials and age on the performance,using four evaluation indexes,i.e.,cubic compressive strength,elasticity modulus,triaxial compressive strength,and permeability coefficient.Results show that all of these schemes can meet the engineering requirements.And when the clay content is within a certain range(<80 kg/m3),concrete strength is reduced with an increase in it while elastic modulus varies in the opposite trend;when the content is bigger than 80 kg/m3,a further increase causes elastic modulus to fluctuate within a certain range but no significant change in concrete strength.The concrete strength and elastic modulus are positively correlated with the cement content,while negatively correlated with the bentonite content.Under triaxial confining pressure,the two sets of optimal mix proportion feature a compressive strength increased by 19%on average at the 90 d age compared to the28 d age,and their permeability coefficients at 90 d age are lower than those at 28 d age.