聚丙烯纤维改性多孔生态混凝土的制备及性能研究

Preparation and performance study of polypropylene fiber modified porous ecological concrete

以聚丙烯纤维为增强相,制备了聚丙烯纤维改性多孔生态混凝土,研究了纤维掺杂量对混凝土微观形貌、力学性能、抗冻性能的影响。结果表明,适量的聚丙纤维掺杂到多孔生态混凝土中后被混凝土基体紧密包裹,在混凝土内部形成了稳固的纤维网络结构,使混凝土粗骨料之间的胶结力得到提高,抗变形能力增强,裂纹和骨料脱落的现象减少。当聚丙烯纤维掺杂量为0.9%(体积分数)时,混凝土的抗压强度、抗折强度、峰值应力和挠度均达到最大值,分别为29.95,5.04,28.00 MPa和6.8 mm。混凝土残余承载力从大到小依次为PP-0.9%>PP-0.6%>PP-0.3%>PP-1.2%。150次快速冻融测试后,随着聚丙烯纤维掺杂量的增多,混凝土的质量损失率先减小后增大,相对动弹性模量先增大后降低,当聚丙烯纤维掺杂量为0.9%(体积分数)时,混凝土的质量损失率最小为1.38%,相对动弹性模量最大为90.45%。综合可知,聚丙烯纤维掺杂量0.9%(体积分数)的混凝土的力学性能和抗冻性能最优。

Polypropylene fiber was used as the reinforcing phase to prepare polypropylene fiber modified porous ecological concrete.The effect of fiber doping on the microstructure,mechanical properties,and frost resistance of the concrete was studied.The results showed that the appropriate amount of polypropylene fibers were tightly wrapped in the concrete matrix after being doped into the porous ecological concrete,forming a stable fiber network structure inside the concrete,which improved the bond strength between the coarse aggregates of the concrete,enhanced the resistance to deformation,and reduced the phenomenon of cracks and aggregate detachment.When the doping amount of polypropylene fiber was 0.9 vol%,the compressive strength,flexural strength,peak stress and deflection of concrete all reached their maximum values,which were 29.95,5.04,28.00 MPa,and 6.8 mm,respectively.The residual bearing capacity of concrete decreased in the order of PP-0.9%>PP-0.6%>PP-0.3%>PP-1.2%.After 150 rapid freeze-thaw tests,with the increase in the amount of polypropylene fiber doping,the concrete quality loss first decreased and then increased,and the relative dynamic elastic modulus first increased and then decreased.When the amount of polypropylene fiber doping was 0.9 vol%,the minimum concrete quality loss rate was 1.38%,and the maximum relative dynamic elastic modulus was 90.45%.From the comprehensive analysis,it can be concluded that the mechanical properties and frost resistance of concrete with a polypropylene fiber doping content of 0.9 vol%are the best.