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

以玄武岩碎石为天然粗骨料,废弃混凝土为再生粗骨料,聚丙烯纤维为增强相,制备了不同聚丙烯纤维掺杂量的多孔生态混凝土,探究了聚丙烯纤维的掺杂量对多孔生态混凝土的物理性能、微观形貌、力学性能及抗冻性能的影响。结果表明,多孔生态混凝土的透水系数和孔隙率呈现出正向线性关系,随着聚丙烯纤维掺杂量的增大,混凝土的透水系数和孔隙率持续降低;适量聚丙烯纤维的掺杂能够在多孔生态混凝土中形成均匀致密的网格结构,当聚丙烯纤维的掺杂量为3%(体积分数)时,混凝土的致密度最高。随着聚丙烯纤维掺杂量的增大,混凝土的抗折强度先增大后降低,抗压强度先快速增大后缓慢增大。在28 d龄期下,当聚丙烯纤维的掺杂量为3%(体积分数)时,混凝土的抗折强度达到最大值4.68 MPa,对应的抗压强度为14.68 MPa。经历100次冻融循环后,当聚丙烯纤维的掺杂量为3%(体积分数)时,混凝土的质量损失率最低为2.17%,相对动弹性模量最高为84.81%,抗冻性能最佳。因此,聚丙烯纤维的最佳掺杂量为3%(体积分数)。

Porous ecological concrete with different polypropylene fiber doping levels was prepared using basalt crushed stone as natural coarse aggregate,waste concrete as recycled coarse aggregate,and polypropylene fiber as reinforcement phase.The influence of the doping amount of polypropylene fibers on the physical properties,microstructure,mechanical properties,and frost resistance of porous ecological concrete was explored.The results indicate that the permeability coefficient and porosity of porous ecological concrete exhibit a positive linear relationship,and as the doping amount of polypropylene fibers increases,the permeability coefficient and porosity of concrete continue decreasing.The moderate doping of polypropylene fibers can form a uniform and dense grid structure in porous ecological concrete.When the doping amount of polypropylene fibers is 3 vol%,the density of concrete is the highest.As the doping amount of polypropylene fibers increases,the flexural strength of concrete first increases and then decreases,and the compressive strength first increases rapidly and then slowly increases.At the age of 28 d,when the doping amount of polypropylene fibers is 3 vol%,the maximum flexural strength of concrete reaches 4.68 MPa,corresponding to a compressive strength of 14.68 MPa.After 100 freeze-thaw cycles,when the doping amount of polypropylene fiber is 3 vol%,the minimum mass loss rate of concrete is 2.17%,and the maximum relative dynamic elastic modulus is 84.81%,indicating the best frost resistance performance.Therefore,the optimal doping amount for polypropylene fibers is 3 vol%.