Preparation And Engineering Application Of Pozzolanic Composite Mineral Admixture Concrete

With the increasing use of concrete in the construction industry,mineral admixture resources have become increasingly scarce.In southeastern Chongqing,it is generally difficult to purchase high-quality fly ash and other traditional mineral admixtures,so local stone powdery materials have to be used,and the local industrial solid wastes have not been properly utilized.In this paper,the local pozzolanic materials and limestone materials that meet the admixture requirements in Youyang area are used as raw materials.By comparing the compressive strength,flexural strength and activity index of the mortar specimens,the composite ratio of the two materials is determined.Sorting,compounding and grinding to make pozzolanic composite admixture products.This not only alleviates the scarcity of local fly ash and other traditional admixtures,but also improves the performance deficiencies of single admixtures and meets the current development concept of green building materials.The prepared composite admixtures were subjected to laboratory concrete performance tests and on-site solid structure concrete application,quality control and acceptance evaluation.The quality control content is mainly composed of three parts:concrete production,on-site pouring and concrete specimen tracking of the mixing station.The compressive strength test of the two cube specimens of standard curing and the same condition curing is carried out,and the on-site solid structure is sampled and returned.Bouncing test.The acceptance process mainly refers to the relevant regulations of the concrete structure engineering construction,and explores the production quality control,project construction management,construction quality control and inspection of the mixing plant.The impact of the composite admixtures used in the local actual project in Youyang on the performance and structural reliability of concrete is evaluated,which is the basis for the qualification of the pozzolanic composite admixture product and the construction quality acceptance management system of the corresponding admixture concrete project.Improve and provide some experimental basis,and the conclusions are as follows:(1)The composite admixture has a more obvious effect on improving the mechanical properties of higher-strength concrete and the strength increase in the later curing period.The optimal content of C30 and C50 concrete is about 15%.The dosage should be controlled within 25% and 35% respectively;(2)When the compound admixture content is about 35%,the electric flux of the two strength grades of concrete has the largest decrease,which is more than 20% lower than the benchmark group,and the resistance to chloride ion penetration is increased by one level;(3)Taking the two common strength grades of mineral admixture concrete,C30 and C50,produced and used in Youyang local mixing station as the experimental object.The relationship and the law of increasing with the curing age between the four strength values,the "standard curing specimen strength" and "same condition curing strength","structural rebound value" and "core sample strength" are studied.The test results show that the four strength values have a strong correlation with the age.The strength of the solid structure pozzolanic composite admixture concrete increases with the logarithmic value of the age,and the later strength increases obviously and relatively stable,indicating the use The time for strength testing and structural acceptance of this type of admixture concrete should be appropriately extended.(4)The influence of the pozzolanic composite admixture on the anti-chloride ion permeability of concrete is also reflected in the later curing age.The electric flux of concrete shows a downward trend as the logarithmic value of age increases,and it has a good correlation with the value of concrete compressive strength.In the case of inaccurate strength value test results or indestructible solid structure,the electrical flux test result can be used as a reference for the construction quality acceptance of the pozzolanic composite admixture concrete with solid structure.(5)Through the experimental exploration of the performance,mechanical properties and durability of the composite admixture concrete mixture,as well as the quality inspection and acceptance evaluation for engineering use,it can be shown that the pozzolanic composite admixture in this paper can meet the requirements of engineering use.The composite admixture concrete can ensure the safety and reliability of the structure.