Effect Of Undisturbed Phosphogypsum On Properties Of Ceramsite Concrete

Since entering the 21st century,with the rapid development of China’s society,the construction industry has also undergone earth shaking changes.In recent years,the increasing requirements for building materials and environment have made it difficult for ordinary concrete to meet the needs of all buildings.Therefore,lightweight aggregate concrete has gradually entered the construction industry,opening the era of rapid development of lightweight aggregate concrete.In addition,with the increasing awareness of green environmental protection,the recycling and reuse of industrial waste as mineral admixtures for concrete has received widespread public attention.The rational utilization of these industrial by-products not only alleviates the problem of industrial waste disposal,but also follows the green environmental protection concept of waste reuse,becoming an important research direction in modern concrete technology.From the perspective of reducing the energy consumption in the construction process,and combining the characteristics of fly ash,phosphogypsum and slag micro powder,which are solid wastes integrated by modern industrial production,this paper attempts to explore the use of the above three minerals to replace a certain amount of cement glue,forming a composite glue system,and mixing it with ceramsite lightweight aggregate to prepare lightweight ceramsite concrete with light weight and high strength,And experimental research was conducted on the relevant properties of concrete.The main research content and conclusions of this article are as follows:(1)Tested the performance indicators of aggregates.The test results of parameters such as bulk density,compressive strength,and water absorption of ceramic coarse aggregate are as follows: the bulk density is 820Kg/m3,compressive strength is 6.6Mpa,and water absorption is 2% after 1 hour.(2)By controlling factors such as cementitious materials,water cement ratio,and sand ratio,the mix design and optimization of concrete are carried out to obtain the benchmark mix ratio for the final test.Test benchmark ratio: cement 460Kg/m3,water160Kg/m3,sand 790Kg/m3,ceramic particle 620Kg/m3,and water reducing agent18.4Kg/m3.The water cement ratio is 0.34,the sand ratio is 42%,and the total volume of coarse and fine aggregates is 1.3.(3)Taking Lc30 concrete as the benchmark,the following tests were carried out in turn: single addition of phosphogypsum,compound addition of fly ash and phosphogypsum,compound addition of mineral powder and phosphogypsum,and triple addition of orthogonal tests to analyze the influence of admixtures on the workability and strength of ceramsite concrete.The results show that: 1)the workability of concrete mixed with phosphogypsum and other minerals is good and meets the mixing requirements;2)When phosphogypsum is added alone,4% is the optimal amount;when fly ash and phosphogypsum are mixed together,15% of fly ash and 4% of phosphogypsum are the optimal amount;when mineral powder and phosphogypsum are mixed together,20% of mineral powder and 4% of phosphogypsum are the optimal amount.Through the calculation and analysis of the range of orthogonal test,the optimal mixing amount of fly ash,phosphogypsum and mineral powder is determined as 15%,2% and 25% respectively.(4)Conducted durability tests and insulation performance tests on ceramsite concrete.Different groups of concrete were subjected to freeze-thaw cycles to test their frost resistance under different mineral admixtures.The experiment showed that there were differences in the number of freeze-thaw cycles and the frost resistance of concrete specimens was different;The influence of phosphogypsum on the shrinkage of ceramsite concrete was tested;The thermal conductivity test of concrete insulation was conducted,and the results showed that the thermal conductivity of concrete thermal conductivity boards with different mix proportions was between 0.19 and0.22(W/m·K).(5)SEM tests were conducted on specimens with single,compound,and triple mineral admixtures.The SEM results indicate that mineral admixtures are added to their own particles to fill the gaps in the aggregate,enhancing the compactness of the cementitious material matrix in concrete;And the products involved in the hydration reaction will also enhance the adhesion between the aggregate and the adhesive material.The research and utilization of industrial wastes such as phosphogypsum,fly ash and mineral powder can achieve multiple benefits of reducing waste accumulation,improving ecological environment,raising the level of industrial waste utilization and realizing the sustainable development of resources.