**2. Used foundry sand**

Used foundry sand (UFS), waste foundry sand (WFS), or spent foundry sand (SFS) is obtained from the released waste molds and cores from the foundries. The released molds' and cores' size and shape are different depending on the casting. The discarded molds and cores can be directly used for filling low lying areas. However, there may be a chance of contamination of the water sources due to the chemicals present in the waste foundry sand. To employ the used foundry sand for other civil engineering applications, further processing is required.

It should be noted that the waste foundry sand may contain metal and debris present in the discarded molds. However, as per the reports of the American Foundry Society [5], in most of the foundries, sand reclamation units are employed for the removal of metal particles and debris from the waste foundry sand for advanced applications. Two types of foundry sand are generated from foundries. These are named "green sand" and "chemically bonded sand," depending on the binders used in the production of mold or core. About 90% of the used foundry sand comes under the category of green sand only. Processed used foundry sand as per Salim et al. [6] is shown in **Figure 1**.

**5**

1554 kg/m3

*A Review on the Usage of Recycled Sand in the Construction Industry*

*DOI: http://dx.doi.org/10.5772/intechopen.92790*

**3. Properties of used foundry sand**

discussed in detail below.

**Figure 1.** *Used foundry sand.*

**3.1 Physical properties**

The used foundry sand has varied physical, chemical, and mechanical properties. In an examination of the characteristics of waste foundry sand and its leachate, Siddique et al. [7] emphasized that the physical and chemical properties of the used foundry sand mostly depend on the industrial segment for which the casting is made. The physical, chemical, and mechanical properties of used foundry sand are

The physical properties of used foundry sand are showing much diversity across the globe. The green sand and chemically bonded sand have different colors. As per the reports of Federal Highway Administration [8], the color of the green sand is gray or black, and the chemically bonded sand has an off-white or medium tan color. Usually, the size of the majority of the particles in the used foundry sand is in the range of 600–150 microns. The U. S. Department of Transportation [4] stated that the used foundry sand has moderately uniform particle size distribution, with just about 85–95% of the particles between 600- and 150-micron sizes and 5–12% of the particles having less than 75-micron sizes. Usually, the used foundry sand consists of subangular to round-shaped particles. The specific gravity of the used foundry sand depends on the properties of the virgin sand and the type of the binders used. Generally, the specific gravity of spent foundry sand has many variations from foundries to foundries. Javed and Lovell [1] stated that the specific gravity of spent foundry sand varies from 2.39 to 2.55. Bulk density of used foundry sand also depends on the properties of virgin sand and the materials used as binders. Naik et al. [9] reported that the bulk density of used foundry sand varies from 1052 to

. The percentage of the mass of water absorbed to the dry mass of the

material is water absorption. As per the values of water absorption results from the earlier studies reported by Javed and Lovell [1], American Foundrymen's Society [10], and Johnson [11], the used foundry sand has water absorption of 0.45%. Later, it was revealed that the water absorption values of used foundry sand have much

*A Review on the Usage of Recycled Sand in the Construction Industry DOI: http://dx.doi.org/10.5772/intechopen.92790*

**Figure 1.** *Used foundry sand.*

*Sandy Materials in Civil Engineering - Usage and Management*

or "spent foundry sand."

**2. Used foundry sand**

per Salim et al. [6] is shown in **Figure 1**.

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,"

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.

Used foundry sand (UFS), waste foundry sand (WFS), or spent foundry sand (SFS) is obtained from the released waste molds and cores from the foundries. The released molds' and cores' size and shape are different depending on the casting. The discarded molds and cores can be directly used for filling low lying areas. However, there may be a chance of contamination of the water sources due to the chemicals present in the waste foundry sand. To employ the used foundry sand for other civil engineering applications, further processing is required. It should be noted that the waste foundry sand may contain metal and debris present in the discarded molds. However, as per the reports of the American Foundry Society [5], in most of the foundries, sand reclamation units are employed for the removal of metal particles and debris from the waste foundry sand for advanced applications. Two types of foundry sand are generated from foundries. These are named "green sand" and "chemically bonded sand," depending on the binders used in the production of mold or core. About 90% of the used foundry sand comes under the category of green sand only. Processed used foundry sand as

**4**
