Combination Effect of Rice Husk Ash and Eggshell Ash as Cement Replacements in Concrete: A Review
Background: Waste materials from the agricultural and industries can cause problems to human health and the environment when improperly disposed and managed. Due to rapid development in construction, the demand of cement in concrete has increased dramatically. Therefore, wastes such as rice husk, eggshell, glass, fly ash and many more can be used in construction industry to minimize the environmental impact and producingnew material on construction industry. Many studies have been conducted as an effort to find replacement materials to substitute cement in concrete. 
Keywords: rice husk ash, eggshell ash, cement replacement, environment