Effect Of Limestone-Volcanic Ash Combination Admixture On Concrete Performance And Its Engineering Application

In recent years,with the reform of China’s economic system,the traditional"three high"industry-cement is in urgent need of transformation and development.The rapid economic development cannot do without the construction of infrastructure,which cannot do without the concrete demand,therefore the green concrete field of our country rapid development,utilization of tailings and other abundant and cheap resources as admixture has become an industry trend.However,slag,fly ash and silica fume and other commonly used high quality admixture resources is deficient,and limestone,volcano ash is widely distributed in China,and the price is low,the admixture is of great significance to replace the concrete with fly ash and slag etc..This theory is based on the project application,using C30 mass concrete as the research object,through the research on the concrete slump,strength,impermeability and hydration heat and other factors,determine the optimal mix of limestone volcano ash composite admixture for preparing C30 large volume concrete,and should be used in engineering practice,made good effect.On the basis of a lot of preliminary exploratory experiments,the orthogonal experiments were carried out with water consumption,sand rate,limestone powder content and specific surface area,the amount of volcanic ash and the specific surface area as the influencing factors.The study showed that the 10%volcano ash and 10%limestone powder replacing 20%of the cement can be prepared,excellent performance,reasonable C30 limestone volcano ash mass concrete,the best matching ratio for 285kg/m~3 cement,limestone 35.7kg/m~3,35.7kg/m~3 volcano ash,sand gravel975kg/m~3,900kg/m~3,168kg/m~3 and 7.14kg/m~3 water reducing agent.This study utilizes limestone-volcano ash ratio of doped 1:1 composite material prepared by partial replacement of cement concrete,the replacement rate were 0%,10%,20%,30%and 40%,with superplasticizer on concrete strength,slump loss,impermeability and bleeding rate of test.The results show that the strength and impermeability of concrete decrease obviously with the increase of substitution rate,but the performance can meet the requirement of production.For mass concrete,the incorporation of mineral admixtures is the main measure to reduce the hydration heat.It can avoid the excessive amount of cement and cause too much hydration heat to form the temperature difference cracks.The composite mixture of limestone and pozzolanic mass ratio of 1:1 can replace 20%of cement in concrete production,and the performance of the concrete can meet the requirements,and the economic benefits are obvious.On the basis of experimental research,the limestone volcano ash composite admixture C30 large concrete material used for the preparation of the construction project of Guangxi Du’an Yufeng Xijiang India Cements Limited Nissan 6000 tons of cement production line,the site of application for large volume concrete foundation member kiln head and tail,and pre tower clinker silo.All the properties of the condensate meet the requirements of the technical specifications,and provide reference and experience for the application of limestone-ash powder composite admixtures in large-scale engineering projects.