Structural lightweight concrete based on coal ashes (containing undesirable radionuclides) and waste of stone quarries

Utilisation of coal combustion by-products (bottom ash and fly ash) generated at power stations and stone quarries waste (unprocessed crushed sand), for the production of lightweight concrete is being studied at the Research Authority of The College of Judea and Samaria (Ariel, Israel). One of the main contributions of this study is the manufacturing of ecologically friendly lightweight concrete using coal ashes containing different quantities of natural radionuclides. For this goal, a technology for the production of a ternary lightweight concrete based on the use of above-mentioned waste was developed. The conducive features of each material are used in an optimum manner that enables the production of an ecologically friendly concrete with desirable building characteristics. Bottom ash is used as a porous lightweight aggregate. A mixture of the fly ash with the cement forms a dense matrix, which compensates for the low strength of bottom ash particles. Unprocessed crushed sand is used as a diluting non-radioactive material, which reduces the radioactivity of the concrete to a safe level. It is used also to farther increase the strength of the lightweight concrete. Based on laboratory and field studies, the technology that has been developed can be recommended for production of structural lightweight concrete, which complies with the requirements of present standards related to strength and density, as well as to radiological characteristics.