**Abstract**

The construction industry requires natural sand for many applications. The recycled sand obtained from industrial operations can also be utilized in construction activities. Many industries generate waste sand as a byproduct. The material generated from this discarded molds and cores is usually known as "used foundry sand," "waste foundry sand," or "spent foundry sand." A vast quantity of used foundry sand is generating and heaping globally in a day-by-day manner. In this review article, an attempt is made to explore the characteristics and various utilizations of this recycled sand from the foundry industry as a valuable resource material in construction activities. From the analysis of the multiple types of research done so far on the reuse of waste foundry sand, it is found that the waste foundry sand is reusable in different civil engineering applications with added advantages. The advantageous applications of used foundry sand are ranging from the road base material to the substitute to fine aggregate in high-performance self-compacting concrete. More generally used foundry sand in the range of 10–30% is best suitable as a partial substitute to regular sand in mortar and concrete making. The use of recycled sand such as waste foundry sand in the construction industry can not only eliminate the problems of waste management and environmental impacts but also substantially boost up the sustainable developmental activities by way of reducing the consumption of natural resources.

**Keywords:** concrete, mortar, road base, used foundry sand, workability

## **1. Introduction**

From the early civilization of humankind, as a construction material, sand is used extensively. In clay bricks, mud mortars, and lime mortars, the sand finds applications. When the concrete emerged as a construction material, the sand became an integral part of this versatile material. After the stone age, metals were used in making the tools and utensils. For the production of metal items, foundry operations are invariably required. For mold making, the sand has been used from the beginning of the usage of metals in the day-to-day life of the human being. The foundries utilize the sand for two critical applications of mold making and core making. As stated by Javed and Lovell [1], the mold is the outside container of the casting, and the core is the form for achieving the internal shape and cavities within the casted metal structure. Now also, the sand is the primary constituent matter of the mold or core making materials. Silica sand, along with binders

such as clay or sodium chemical binders, is used for the making of the mold for metal casting. Sand with clay is naturally available and is abundantly used in mold making. As per the Bureau of Indian Standards IS 3343 [2], original molding sand used in foundries has clay content varied from 5 to 20%. Dogan-Saglamtimur [3], from the research on the reuse of the waste foundry sand in the manufacture of geopolymer concrete, depicted that foundry sands have a loose structure in nature. After several cycles of reuses, the molding sand or foundry sand from the released molds and cores discarded and becomes industrial wastes. A large quantity of such industrial waste sand is generated from foundries all over the world. U. S. Department of Transportation [4] estimated that 1 ton of casting requires 1 ton of foundry sand approximately. American Foundry Society [5] reported that 100 million tons of sand are using and reusing in foundries per annum in the United States itself. The sand from industrial wastes can be recycled for applications in civil engineering and is called "used foundry sand," "waste foundry sand," or "spent foundry sand."

As the quantity of the used foundry sand is so enormous, the disposal of used foundry sand in landfills is significantly affecting the ecology and the environment. Hence, the reuse of waste foundry sand in civil engineering applications other than a land filling is much beneficial to the society from both economical and environmental point of view. The research on the reuse of waste foundry sand in the construction industry is very much crucial as it is the largest consumer of the virgin sand. As a matter of fact, the natural sources of sand are being affected due to the overconsumption and now facing depletion. Every step toward reducing the use of natural sand by adopting waste foundry sand as a full or partial substitute to natural sand will lead to the preservation of the natural resources and the safe disposal of the industrial waste sand to a beneficial application safeguarding the ecology and the environment. In the following paragraphs, the used foundry sand and their properties are discussed in detail. Also, the utilization of used foundry sand recommended by various researchers in a variety of fields related to the construction industry is addressed with sufficient experimental findings. Since concrete plays a significant role in the construction industry, an extensive study of properties of concrete incorporating used foundry sand is also appended for the easy understanding of the applicability of the used foundry sand in concrete making.
