Study On The Influence Of Undisturbed Phosphogypsum On Concrete Performance

In recent years,with the continuous improvement of people’s awareness of green environmental protection,the application of mineral admixture and admixture especially industrial waste residue in concrete has been widely concerned.Phosphogypsum is a kind of industrial waste residue with low utilization rate,its annual discharge is very high,but the comprehensive utilization rate is less than 30%,so it brings many ecological and environmental problems.The application of phosphogypsum as mineral admixture in concrete can change phosphogypsum from industrial waste to valuable concrete admixture,which has double significance of reducing energy consumption and environmental pollution.This will be a subject worth studying.The research content and main conclusions of this paper are as follows:(1)The effect of phosphogypsum on mechanical properties of different age and curing conditions of colloidal sand and its mechanism were analyzed through colloidal sand test.Main research and conclusions are as follows: 1)Through single phosphorous gypsum mortar test,double phosphorous gypsum and fly ash mortar test study on single phosphorous gypsum,double phosphorous gypsum and fly ash on the mechanical behavior of mortar,the results show that mortar compressive flexural strength increased with the increase of dosage of phosphogypsum are declining,but is less than 4% of phosphorus gypsum content small impact on the mortar strength;2)The orthogonal test of mortar was carried out by taking the different dosage of phosphogypsum,fly ash and mineral powder as three factors to study their influence on the mechanical properties of mortar.The optimal dosage of mortar was found to be 15% of fly ash,20% of mineral powder and 2% of phosphogypsum;3)Comparing the strength of mortar under die curing and standard curing,the results show that the strength under die curing is higher than standard curing,but the strength increases slightly;4)The influence mechanism of phosphogypsum on mechanical properties of colloidal sand was analyzed by SEM.(2)Based on C30 concrete and the conclusion of mortar test,the orthogonal test of concrete with three factors and four levels was carried out with the content of phosphogypsum,fly ash and mineral powder as three factors to study the influence of admixtures on the working performance,mechanical properties and durability of concrete.The results show that: 1)The concrete mixed with phosphogypsum,fly ash and ore powder has good workability,fly ash is beneficial to improve the slump of concrete,but phosphogypsum and ore powder are not conducive to the improvement of the slump of concrete;2)Through the range calculation and analysis of the orthogonal test,it is found that the optimal mixture ratio of concrete is 10% fly ash,20% mineral powder and 2% phosphogypsum;3)Curing with mold is more beneficial to improve the compressive strength of concrete cube than curing with mold removal;4)The mixture ratio of four groups of concrete with high compressive strength selected from orthogonal test meets the requirements of anti-freezing and anti-seepage properties of concrete.(3)The optimum mix ratio obtained in the orthogonal test of concrete is taken as the reference mix ratio,and different amounts of phosphogypsum are added to make concrete-filled steel tubular members.The axial compression test of concrete-filled steel tubular short columns is carried out to study the influence of phosphogypsum content on the ultimate bearing capacity of concrete-filled steel tubular short columns.The results show that 2% phosphogypsum content can improve the ultimate bearing capacity of CFST short columns to a certain extent,and the ultimate bearing capacity of specimens beyond this range will reduce the load-strain curve obtained by analyzing the test,so as to understand the working process of CFST short columns in the axial compression test.The study of phosphogypsum application can improve the level of resource utilization and industrial scale of industrial waste residue,improve the ecological environment,have great practical significance to promote sustainable development.