*Review* **Artificial Lightweight Aggregates Made from Pozzolanic Material: A Review on the Method, Physical and Mechanical Properties, Thermal and Microstructure**

**Dickson Ling Chuan Hao <sup>1</sup> , Rafiza Abd Razak 1,2,\*, Marwan Kheimi <sup>3</sup> , Zarina Yahya 1,2, Mohd Mustafa Al Bakri Abdullah 2,4, Dumitru Doru Burduhos Nergis 5,\* , Hamzah Fansuri <sup>6</sup> , Ratna Ediati 6, Rosnita Mohamed <sup>2</sup> and Alida Abdullah <sup>2</sup>**


**Abstract:** As the demand for nonrenewable natural resources, such as aggregate, is increasing worldwide, new production of artificial aggregate should be developed. Artificial lightweight aggregate can bring advantages to the construction field due to its lower density, thus reducing the dead load applied to the structural elements. In addition, application of artificial lightweight aggregate in lightweight concrete will produce lower thermal conductivity. However, the production of artificial lightweight aggregate is still limited. Production of artificial lightweight aggregate incorporating waste materials or pozzolanic materials is advantageous and beneficial in terms of being environmentally friendly, as well as lowering carbon dioxide emissions. Moreover, additives, such as geopolymer, have been introduced as one of the alternative construction materials that have been proven to have excellent properties. Thus, this paper will review the production of artificial lightweight aggregate through various methods, including sintering, cold bonding, and autoclaving. The significant properties of artificial lightweight aggregate, including physical and mechanical properties, such as water absorption, crushing strength, and impact value, are reviewed. The properties of concrete, including thermal properties, that utilized artificial lightweight aggregate were also briefly reviewed to highlight the advantages of artificial lightweight aggregate.

**Keywords:** artificial lightweight aggregate; geopolymer; aggregate crushing value; aggregate impact value; thermal properties; pozzolanic materials
