Influence of Gypsum Waste Utilization on Properties and Leachability of Fired Clay Brick

Abstract

Wastewater treatment activities in the chemical industry have generated abundant gypsum waste, classified as scheduled waste (SW205) under the Environmental Quality Regulations 2005. The waste needs to be disposed into a secure landfill due to the high heavy metals content which is becoming a threat to the environment. Hence, an alternative disposal method was evaluated by recycling the waste into fired clay brick. The brick samples were incorporated with different percentages of gypsum waste (0% as control, 10, 20, 30, 40 and 50%) and were fired at 1050 °C using 1 °C per minute heating rate. Shrinkage, dry density, initial rate of suction (IRS) and compressive strength tests were conducted to determine the physical and mechanical properties of the brick, while the synthetic precipitation leaching procedure (SPLP) was performed to scrutinize the leachability of heavy metals from the crushed brick samples. The results showed that the properties would decrease through the incorporation of gypsum waste and indicated the best result at 10% of waste utilization with 47.5% of shrinkage, 1.37% of dry density, 22.87% of IRS and 28.3% of compressive strength. In addition, the leachability test highlighted that the concentrations of Fe and Al was significantly reduced up to 100% from 4884 to 3.13 ppm (Fe) and from 16,134 to 0.81 ppm (Al), respectively. The heavy metals content in the bricks were oxidized during the firing process, which signified the successful remediation of heavy metals in the samples. Based on the permissible incorporation of gypsum waste into fired clay brick, this study promised a more green disposing method for gypsum waste, and insight as a potential towards achieving a sustainable end product.

Assessment of Limestone Waste Addition for Fired Clay Bricks

“…We suggest that the maximum amount of limestone waste to be used in combination with the high CO2 emissions is around 5%. Linear decrease in compressive strength as function of used waste (marble waste [35]; municipal solid waste [36]; TFT glass [37]; fly ash [38]; gypsum waste [39]; tuff [28]; limestone waste-present work).…”

“…Some opportunities for and threats of using the limestone waste as an admixture in the clay matrix are summarized in Table 3. [35]; municipal solid waste [36]; TFT glass [37]; fly ash [38]; gypsum waste [39]; tuff [28]; limestone waste-present work).…”

“…In order to compare the magnitude of the reduction in the compressive strength, the slope of the linear regression of the data presented in Figure 9 [28,[35][36][37][38][39] was compared with the data in the literature of other commonly used waste. The positive slope indicated that the waste increased the compressive strength.…”

“…Figure 9. Linear decrease in compressive strength as function of used waste (marble waste[35]; municipal solid waste[36]; TFT glass[37]; fly ash[38]; gypsum waste[39]; tuff[28]; limestone waste-present work).…”

Acoustic Properties of Autoclaved Aerated Concrete (AAC) Based On Gypsum-Ceramic Waste (GCW)

“…Although gypsum waste has been recognized as hazardous waste but the gypsum material has also been approved to have a good building material due to its lightweight, excellent moldability, fire resistance, and sound absorption [7]. Gypsum materials have large uses in material building such as dry wallboards [8], clay brick [9] and fire clay brick [10]. According to Lushnikova and Dvorkin (2016) gypsum materials also have large uses in building materials such as autoclaved cement cellular concrete, non-autoclaved cement cellular concrete, claydite cement concrete, hollow limesand brick, hollow clay brick, ordinary clay brick, cellular gypsum blocks, gypsum concrete blocks (hollow) and gypsum concrete blocks (solid) [11].…”