Study On Solid Preparation Of Concrete For CFG Pile

The utilization rate of red mud was the lowest among the wastes in the nonferrous metal smelting industry,and the pollution during storage was serious.Affected by traditional industries,the stock and output of fly ash were still increasing.The waste clay bricks produced in the demolition and reconstruction of old buildings were mostly piled up in the open air,and the treated aggregate had certain strength and could be reasonably utilized.The use of solid waste is in urgent need of research in sustainable development.If we could find a reasonable way,we could better protect the environment and save resources.In this paper,three kinds of solid wastes were used to replace cement and coarse aggregate to test the mechanical and durability of concrete.Combined with the laboratory test and finite element simulation of CFG pile composite foundation,a comparative analysis was made,and the economy of solid waste concrete and ordinary concrete applied to CFG pile was discussed.The specific research results were as follows:(1)Mechanical and durability testing of solid waste concrete.The changes of cube compressive strength and frost resistance after red mud and other solid wastes were applied to concrete were studied.It was found that the excessive use of three materials would weaken the strength to some extent.Although red mud had a certain excitation effect,the reduction of hydration products and the defects of recycled brick aggregate would still cause the frost resistance to decrease.After many times of freezing and thawing,some specimens could still meet the basic strength requirements of pile concrete.Finally,the relative optimal substitution rate was determined as 10% of red mud,10% of fly ash and 50% of recycled brick aggregate.(2)CFG pile composite foundation test and finite element analysis.During the test,when the load was small,the load-settlement curve showed a linear relationship.And under the maximum load of 38.89 k Pa,the settlement was 3.12 mm,which was close to the calculated value of the code.The stress distribution on the pile tended to the upper part,and the deformation in the upper part was greater than that in the lower part.The axial force decreased with the increase of the depth of the measuring point,reaching the maximum value at about 1/5 of the pile top.The lateral friction was exerted within the whole length of the pile body,and there was no negative friction.Composite foundations with different pile types showed similar bearing capacity in finite element analysis.(3)Economic analysis.Through the cost analysis of the two pile types,it was found that the cost of applying solid waste concrete to CFG pile was about 6% lower than that of ordinary CFG pile,which had practical value and environmental significance for the resource utilization of solid waste.