Study On Mechanical And Thermal Properties Of Foam Concrete With Glass Fiber

The anti-frost heave of the channel is often used to lay extruded polystyrene insulation board(XPS)and then lay concrete on the insulation board.The construction is complicated,the durability of the insulation board is poor,and the project cost is high.In this paper,fiber foam concrete is used as the thermal insulation layer,combined with C20 ordinary concrete to form fiber foam concrete-C20 concrete to replace the channel insulation layer composed of extruded polystyrene insulation board(XPS)and ordinary concrete,which reduces the construction difficulty,improves the engineering economy and prolongs the service life of the channel.In this study,foamed concrete samples with dry density of 800kg/m~3and fiber content of 0,0.3%,0.4%,0.5%,0.6%and 0.7%were prepared.After 28 days of curing,the mechanical properties and thermal properties were tested,and the fiber content with the best thermal-mechanical performance was obtained.Then,the foam concrete under the optimal fiber content is combined with C20 ordinary concrete to form fiber foam concrete-C20 concrete.The mechanical properties and thermal properties of fiber foam concrete-C20 concrete are measured through experiments to explore the performance differences between fiber foam concrete-C20 concrete and ordinary concrete and foam concrete.ABAQUS software is used to simulate and compare fiber foam concrete-C20concrete and channel insulation board.The main conclusions are as follows:(1)The test results of different fiber content show that with the increase of fiber content,the compressive strength and flexural strength of foam concrete increase first and then decrease,and when the fiber content is 0.4%,the compressive strength and flexural strength of fiber foam concrete reach the maximum.The thermal conductivity shows an increasing trend;the water absorption rate shows a decreasing trend.According to the test results,the fiber foam concrete with 0.4%fiber content is selected as the thermal insulation material of the fiber foam concrete-C20 concrete structure.(2)With the increase of age,the compressive strength of fiber foam concrete-C20concrete,foam concrete and C20 ordinary concrete showed an increasing trend.The thermal conductivity of fiber foam concrete-C20 concrete and foam concrete shows a trend of decreasing and then increasing,and the thermal conductivity of C20 ordinary concrete shows a trend of increasing.The water absorption of fiber foam concrete-C20 concrete,foam concrete and C20 ordinary concrete shows an increasing trend.In terms of compressive strength,the compressive strength of C20 ordinary concrete is the largest,the compressive strength of fiber foam concrete-C20 concrete is the second,and the compressive strength of foam concrete is the smallest.In terms of thermal conductivity,the thermal conductivity of C20 ordinary concrete is the largest,the thermal conductivity of fiber foam concrete-C20concrete is the second,and the thermal conductivity of foam concrete is the smallest.In terms of water absorption,the water absorption rate of foam concrete is the highest,the water absorption rate of C20 ordinary concrete is the lowest,and the water absorption rate of fiber foam concrete-C20 concrete is between foam concrete and ordinary concrete.According to the test results,the fiber foam concrete-C20 concrete can replace the channel structure composed of extruded polystyrene insulation board(XPS)and ordinary concrete.(3)The ABAQUS software was used to compare and analyze the fiber foam concrete-C20 concrete and the channel lining structure composed of extruded polystyrene insulation board(XPS)and ordinary concrete.The simulation results show that in terms of temperature field,the heat transfer effect of fiber foam concrete-C20 concrete lining insulation layer and insulation board lining insulation layer is not much different.The frost depth line of fiber foam concrete-C20 concrete lining bottom slope is 0.789 m,the frost depth line of sunny slope is 1.44 m,and the frost depth line of shady slope is 1.41 m.The frost depth line of the bottom slope of the insulation board lining is 0.756 m,the frost depth line of the sunny slope is 1.35 m,and the frost depth line of the shady slope is 1.29 m.The frost depth line of the fiber foam concrete-C20 concrete lining is slightly deeper than that of the warm plate lining.In terms of displacement field,because the weight of the fiber foam concrete-C20 concrete lining is larger than that of the insulation board lining,the frost heave amount is slightly larger than that of the insulation board lining.The maximum frost heave amount of the fiber foam concrete-C20 concrete lining is 0.1129 m,and the maximum frost heave amount of the insulation board lining is 0.0916 m.Therefore,it is feasible to replace the channel lining insulation layer composed of extruded polystyrene insulation board(XPS)and ordinary concrete with fiber foam concrete-C20 concrete.