人工砂中游离云母含量对碾压混凝土性能的影响研究

Study on the Influence of Free Mica Content in Artificial Sand on the Performance of Roller Compacted Concrete

采用4种不同游离云母含量的人工砂分别拌制碾压混凝土,研究游离云母含量对碾压混凝土VC值、力学性能、耐久性能及干缩变形性能的影响规律。结果表明:随人工砂中游离云母含量增高,碾压混凝土拌合物VC值明显增大,工作性能降低且云母含量越高影响越显著,当云母含量从0%增加到8.7%时,VC值从4.5 s增加到9.3 s;抗压强度、轴拉强度及静压弹模随云母含量增高均呈下降规律,且云母含量越高强度降低率越大,后期强度降低率相比早期更大,轴拉强度降低率略大于抗压强度。抗冻性能随云母含量增高呈逐渐降低趋势,当云母含量不大于3.9%时,混凝土抗冻性能尚能满足F200级抗冻要求,当云母含量达到8.7%时抗冻性能出现明显劣化;抗渗性能随云母含量增高总体呈下降趋势,但影响的程度较小,4组不同云母含量碾压混凝土均能满足W6抗渗等级要求;云母含量对碾压混凝土干缩变形性能影响不大。

Four types of artificial sand with different free mica contents are used to make roller compacted concrete,and the influence of free mica content on the VC value,mechanical properties,durability,and dry shrinkage deformation performance of roller compacted concrete is studied.The results show that as the free mica content in artificial sand increases,the VC value of the RCC mixture significantly increases,and the working performance decreases.The higher the mica content,the more significant the impact.When the mica content increases from 0%to 8.7%,the VC value increases from 4.5 seconds to 9.3 seconds;the compressive strength,axial tensile strength,and static elastic modulus all decrease with the increase of mica content,and the higher the mica content,the greater the strength reduction rate.The strength reduction rate at late stage is greater than the early stage,and the axial tensile strength reduction rate is slightly greater than the compressive strength.The frost resistance of concrete gradually decreases with the increase of mica content.When the mica content is not more than 3.9%,the frost resistance of concrete can still meet the requirement of Grade F200.When the mica content reaches 8.7%,the frost resistance performance shows significant deterioration;the anti-permeability performance generally decreases with the increase of mica content,but the impact is relatively small.All four groups of roller compacted concrete with different mica content can meet the requirements of W6 anti-permeability grade;the mica content has little effect on the dry shrinkage deformation performance of roller compacted concrete.