关键词: 聚丙烯纤维;水泥砂浆;数字散斑;变形场演化;塑性

Abstract: In order to study the deformation damage law of cement mortar samples mixed by polypropylene fiber under different curing ages, uniaxial compression test was conducted for cement mortar samples.Lateral deformation field was observed by digital speckle correlation method, and fracture morphology was observed by scanning electron microscope.The results show that compressive strength increases first and then decreased with the increase of polypropylene fiber content at the same curing age.In the range of variable gradient, the optimum quantity of polypropylene fiber is 0.5%.In post-peak, the samples containing polypropylene fiber exhibited a obvious plastic characteristics and the generalized stiffness coefficient changed greatly.The evolution of lateral deformation field was divided into four stages, uniform stage, nucleation stage, deformation localization stage and failure stage.Bond strength of polypropylene fiber and cement mortar was weaker than that of sand and cement.The failure mode of polypropylene fiber samples exhibited fissure but continuous.The microscopic bond contact model put forward in this research can be used to explain the characteristics of plastic improvement of polypropylene fiber samples in post-peak.

Key words: polypropylene fiber;cement mortar;digital speckle;deformation field evolution;plasticity