Study On The Properties Of Concrete Mixed With Rice Husk Ash

Cement is one of major building materials,but its production consumes lots of natural resources and generates many pollutants.Rice husk ash is agricultural solid waste residue after burning of rice husks,while slag and fly ash are industrial solid waste residue from steelmaking and coal-fired power generation.Concrete preparation with solid waste residue instead of traditional materials can reduce environmental pollution,save resources,reduce costs and improve concrete properties.This paper aims to combine pollution-free rice husk ash and alkali-activated concrete and replace microsilica and cement with rice husk ash and alkali-activated cementitious material to research paste,concrete and foam concrete as follows:First,the law by which rice husk ash affects the compressive strength and flexural strength of cement paste and alkali-activated paste were researched.It was found that the addition of rice husk ash promotes the development of compressive strength and flexural strength of cement paste and alkali-activated paste.The recommended optimal substitution rate of rice husk ash for cement paste is 20%,and that for alkali-activated paste is 10%.Second,the law by which rice husk ash affects the physical properties,mechanical properties and durability of cement concrete and alkali-activated concrete were researched.It was found that the addition of rice husk ash promotes hydration reaction and improves early strength;as rice husk ash increases,concrete improves its mechanical properties and resistance to sulfuric acid corrosion and carbonization but its shrinkage increases;despite the similar properties,rice husk ash is more applicable for alkali-activated concrete than microsilica.Third,the law by which rice husk ash affects the physical properties and mechanical properties of cement foam concrete and alkali-activated foam concrete were researched.It was found that alkali-activated foam concrete prepared with rice husk ash has better properties than cement foam concrete,so it has feasibility of practical application.Fourth,mercury intrusion method and scanning electron microscopy were used to research the effects of rice ash ash on the pore structure and microstructure of cement paste and alkali-activated paste and reveal the mechanism of the effects of rice husk ash on concrete properties.