Preliminary studies were conducted on different types of sands, namely, fresh sand, facing sand and backing sand. The analytical investigations such as surface morphology obtained from Scanning Electron Microscope (SEM) and XRD patterns revealed that there is no significant change in the crystal structure of different types of sands mentioned above. It was important to investigate the changes taking place on the sand surface in the presence of sodium silicate which was added as a binder. Further, research was carried out to investigate the effect of this binder on silica sand at different temperatures. Batch experiments were carried out to clear the surface of the sand grain using different chemicals such as water, glucose, hydrochloric acid (HCl) and ammonium sulphate ((NH4)2SO4) with different concentrations. Thus, treated sand was checked for core hardness and compressive strength by making suitable sand molds. To understand the changes taking place on the surface of sand after treatment, Fourier Transform Infrared Spectroscopy (FTIR) was used. The change in the functional groups of facing sand and treated sand was analyzed. The sand treated with 0.5M Hydrochloric Acid (HCl), which showed best results in terms of compressive strength, was selected for FTIR analyses. The FTIR spectra of treated sand with 0.5M HCl showed the absence of the O–H stretch, which is an indication of the presence of free hydroxyl groups at the band 3640-3200.

Sand mining is the extraction of sand from their natural composition. Sand is used for many kinds of projects like construction, land reclamations, coastline stabilization and casting process in foundries. These projects have many economic and social benefits, but sand mining causes many environmental problems. Environmental problems occur when the rate of sand extraction exceeds the rate at which natural processes generate sand (Byrnes and Hiland, 1995).

Foundry technologies depend completely on sand as a component of multipurpose molding and core making. Casting production from sand molds was evaluated to about 80% of total world castings. Technologies which are developed in recent days are also using silica sand as base material in mold and core processes (Kanicki, 2000).

Foundries reuse sand many times. Sand is removed from the foundry when it can no longer be reused in the foundry, and is termed as Waste Foundry Sand (WFS) (Alonso-Santurde et al., 2012). Depending on the type of casting process and the industry sector, the physical and chemical characteristics of foundry sand can be determined. In modern foundry practice, sand is typically recycled and reused through many production cycles. American foundry industry estimates that approximately 100 million tons of sand are used in production annually, out of which, United States alone discards 6-10 million tons annually. The automotive industries and its parts are the major generators of foundry sand. Foundries purchase high quality size-specific silica sands for use in their molding and casting operations (Siddique, 2009).

Structural Engineering Journal, Foundry sand, Microscopic analysis, Treatment