红黏土及水泥掺量对塑性混凝土性能影响研究

Influences of red clay and cement content on concrete performance

本文研究结合云南红土地区,采用3个系列15组配合比,通过进行塑性混凝土抗压强度、劈裂抗拉强度、抗折强度、弹性模量及渗透系数试验,对比研究红黏土及水泥掺量对塑性混凝土性能的影响。3个系列对应的水泥掺量分别为120 kg/m3、150 kg/m3和180 kg/m3,每个系列下的5组红黏土掺量分别为0 kg/m3、50 kg/m3、100kg/m3、150 kg/m3和200 kg/m3。试验结果表明：当水泥掺量相同时,随着红黏土掺量从0 kg/m3增加至200 kg/m3,N1、N2、N3系列塑性混凝土弹性模量分别降低了45.3%、23.0%和14.6%,渗透系数分别降低了57.8%、56.6%和78.1%,均呈显著下降,28 d抗压强度、28 d劈裂抗拉强度和28 d抗折强度亦呈不同程度下降;当红黏土掺量相同时,随着水泥掺量从120 kg/m3增加至180 kg/m3,不同系列塑性混凝土弹性模量分别增加了107.6%、116.7%、149.2%、184.8%和224.5%,28 d抗压强度、28 d劈裂抗拉强度和28 d抗折强度强度增幅均超过30%,上升显著。其中,当水泥掺量超过150 kg/m3时,28 d抗压强度、28 d劈裂抗拉强度和28 d抗折强度增幅变大,弹性模量增幅明显变小,渗透系数降幅明显变大。研究发现,当水泥掺量在150~180 kg/m3,红黏土掺量在150~200 kg/m3范围内,塑性混凝土性能最优。研究成果对塑性混凝土在云南红土地区水利工程中应用,具有重要的理论意义和应用价值。

This paper presents a comparative experimental study on the influences of red clay and cement content on concrete performance, comparing three series and fifteen sets of different mix proportion, focusing on the behaviors of plastic concrete in compressive strength, splitting tensile strength, bending strength, elastic modulus, and permeability coefficient, and considering the soil areas in Yunnan. The cement content of the three series was 120, 150 and 180 kg/m3; the red clay content of five sets for each series 0, 50, 100, 150 and 200 kg/m3. Test results showed that for the plastic concrete of the three series with a certain fixed cement content, as its red clay content was increased from 0 to 200 kg/m3, its elastic modulus was decreased by 45.3, 23.0 and 14.6% for respectively, and its coefficient of permeability decreased by 57.8, 56.6 and 78.1% respectively, showing a steep dropping trend. And its corresponding compressive strength, splitting tensile strength and bending strength at 28 d age, all showed dropping trends but at different rates. For the plastic concrete of different series with a certain fixed red clay content, as its cement content was increased from 120 to 180 kg/m3, its elastic modulus was increased by 107.6, 116.7, 149.2, 184.8 and 224.5% respectively and a significant increase of more than 30% observed in these three strength parameters. In particular, when its cement content exceeded 150 kg/m3, all its strength parameters took a larger increasing rate, its elastic modulus decreased much slower, and its permeabilitycoefficient grew at a considerably greater rate. Furthermore, the plastic concrete achieved an optimal performance in the condition of cement content of 150 - 180 kg/m3 and red clay content of 150 - 200 kg/m3. This study would provide an important technical support to the application of plastic concrete to water conservancy projects in the Yunnan red clay areas.