• Ayyub, Muhammad Faisal
• Afzal, Muhammad
• Rehman, Safi Ur
• Ng, Hei Yi
• Eddie, Lam Siu Shu

Abstract

<jats:p>This study aims at the sustainable valorization of eggshells (ES) from different countries of origin in cement concrete as a cement replacement for Hong Kong. For this purpose, sixteen different eggs from different regions across the world were selected from the local market. Firstly, the extent of uniformity in the weight and mineral content of sampled eggshells were assessed by a specific gravity test and thermogravimetric analysis (TGA), respectively. It was found that specific gravity varies between 2.02 and 2.39, with an average value of 2.20 &amp;plusmn; 0.01, whereas CaCO3 varies between 94.65% and 97.23%, with an average value of 96.33%. These values were a bit lower than those of extra-pure limestone (LS) because of the organic part and the porous structure of eggshells. Secondly, three different eggshells were selected for cement replacement in cement concrete, both in the uncalcined and calcined states, based on having the highest, medium, and lowest CaCO3 content, respectively. To get the calcined eggshells, the eggshells were calcined at 800oC for three hours. It was found that the strength of eggshells varies with CaCO3, but the variation was acceptable. The calcined eggshells showed comparatively more compressive strength and were close to the LS because of the free CaO and the absence of an organic part. In general, the variation in the basic properties of eggshells from different regions across the world is negligible and suitable to use as a cement replacement with acceptable variation in strength in Hong Kong.</jats:p>

Topics

• porous
• impedance spectroscopy
• mineral
• strength
• cement
• thermogravimetry
• laser sintering