| As a new construction material, fiber reinforced concrete (FRP) has been widely used in the domain of civil engineering. Durability characteristics of material including freeze-thaw resistance, infiltration resistance and erosion resistance are crucial to the function and security of concrete structures, therefore a great deal of attention has been given to the investigation on the durability of concrete. The project studies on the fiber influence on the freeze-thaw behaviour and early-age plastic shrinkage properties of fiber reinforced high performance concrete (FRHPC). In this test, fiber types are including high alkali-resistant glass fiber, steel fiber and hybrid fiber (high alkali-resistant glass fiber and steel fiber), and the advantages of high performance concrete are well workability and higher strength.Based on the investigations on the workability, air content and compressive strength of FRHPC, this paper analyses the influence of high alkali-resistant glass fiber, steel fiber and hybrid fiber on the early-age shrinkage cracking, and also compares the compressive strength, splitting tensile strength and flexural toughness of FRHPC before and after 200 freeze-thaw cycles, using the rapid freezing and thawing method. The test methods are adopted from Technique Regulations for Fiber Concrete Structure of China and international guidelines. Meanwhile, the paper analyses the concrete samples with different fiber content and dosage before and after freeze-thaw test using scanning electron microscope, in order to discuss the influence of freeze-thaw cyclings on the microcosmic structure of FRHPC.The study on the early-age (0～20h) plastic shrinkage cracking of FRHPC shows that hybrid fiber reduces the area and width of shrinkage cracks of high performance concrete remarkably, and the efficiency degree of hybrid fiber reinforced high performance concrete is higher than that of mono fiber reinforced high performance concrete. Steel fiber which fiber dosage is 20kg/m~3 or 30kg/m~3, is more effective to restrain the initiation of early-age cracking than glass fiber which fiber dosage is less and equal than 6kg/m~3.The study on the freeze-thaw test of FRHPC shows that steel fiber, especially hybrid fiber, improves scaling resistance, compressive strength, splitting tensile strength, flexural toughness and brittleness of high performance concrete remarkably both before and after freezing and thawing test, and glass fiber has the advantage of improving the splitting tensile strength of high performance concrete before and after freezing and thawing cyclings. |
