| High strength concrete has high strength and compactness and has wide application prospect in coastal engineering.Although high-strength concrete has the advantages of high strength and good durability,the increase of strength is accompanied by the increase of brittleness.At the same time,with the growth of service time of coastal engineering structures,the late strength of high-strength concrete in wet environment decreases,affecting the safety of structures.The strength and toughness of high strength concrete can be improved effectively by adding synthetic fiber with high strength and good corrosion resistance under standard curing condition.But for now,at home and abroad for wet synthetic fiber reinforced high strength concrete under the environment of late performance research is in its infancy,therefore,in this paper,the wet and heat curing and seal curing late synthetic fiber reinforced high strength concrete under the condition of basic mechanical properties,resistance to permeability and the microcosmic structure to carry out the test and research,to explore the synthetic fiber on the properties of high strength concrete in the late,The specific research contents are as follows:Five groups of different fiber volume dosage were set,which were 0%,0.5%,1.0%,1.5%and 2.0%,respectively.The standard curing period was 7d,28 d and 60 d,and 1d,2D,3D,5d,9d and 14 d were moist-heat curing and sealing curing after 60 d of standard curing.The compressive and splitting tensile strength tests of synthetic fiber reinforced high strength concrete were carried out.The results show that the compressive strength and splitting tensile strength of synthetic fiber reinforced high strength concrete increase to the peak at first and then decrease to a certain extent with the growth of age under humid heat curing condition.At the same time,the compressive strength of concrete increases with the increase of fiber content.When fiber content is 1.5%,the compressive strength of concrete is the best,and its value is 124.5MPa.When the content of synthetic fiber continues to increase to 2.0%,the compressive strength decreases to a certain extent.The splitting tensile strength increased with the increase of fiber content.When the fiber content was 2.0%,the splitting tensile strength reached the highest value of 8.46 mpa.Under the condition of sealed curing,the specimen with fiber content of 2.0% shows better mechanical properties in all ages compared with the specimen without fiber.The chloride penetration resistance test and water absorption test were carried out for each group of synthetic fiber reinforced high strength concrete.The results show that the impermeability of high strength concrete reinforced with synthetic fiber increases firstly and then decreases with the increase of the content of synthetic fiber.Meanwhile,the impermeability of the specimen in sealed curing condition is better than that in moist and heat curing condition.Mercury injection test was used to analyze the pore structure of synthetic fiber reinforced high strength concrete.The results show that the addition of fiber changes the internal pore structure of concrete and increases the porosity and average pore diameter of synthetic fiber reinforced high strength concrete.Meanwhile,the proportion of harmful and harmless pores increases with the increase of fiber content. |
