Agricultural wastes preparation, management, and applications in civil engineering: a review

The incineration of agricultural wastes (agro wastes) as a fuel, solid fuel, and/or for the same purposes, resulting in landfilled ash that in most cases makes an environmental problem due to disposal. These landfilled most of the time contain valuable elements such as silica and alumina which are promising alternatives to be used in value-added engineering products. With this regard, the optimal use of these wastes has always been a concern for researchers, and the utilization of them for different purposes is an effective way of management. Although in recent years, the beneficial use of agro waste ashes has been considered by many researchers in different engineering fields, according to the preparation conditions and activation techniques, different kinds of ashes are produces. Therefore, according to the composition of final product, various applications are considered including wastewater treatment, additive for cement industry, and alkali-activated materials, as an additive for production of glass, silicate, pure silica, silicon carbide, refractory materials, as filler in thermoplastics and rubbers, reinforcing agent, and adsorbent in polymer composites and epoxy thermostable polymers, for producing advanced materials such as Silicon nitrite (Si3N4) and magnesium silicide (Mg2Si), and many more. The present paper surveys the preparation steps and techniques for activation of rice husk ash as one of the most used agro waste ash and its applications in engineering fields.