Solidification/Stabilization (S/S) method with cement as a binder to remediate metals in petroleum sludge has been successfully proven. However, this technique has not yet been explored to remediate organic contaminants since a high concentration of Total Petroleum Hydrocarbon (TPH) was also detected in the sludge. This study focuses on remediating 16 Polycyclic Aromatic Hydrocarbons (PAHs) compounds in raw petroleum sludge with Portland cement as a binder using the S/S method. The initial concentration of 16 PAHs in the raw sludge was first measured before the performance of the S/S method to remediate the PAHs were evaluated. The S/S matrices were tested for leaching behavior and strength after 7 and 28 days by air curing. The leaching test was measured using the Toxicity Characteristics Leaching Procedure (TCLP), and the remaining PAHs concentration in the matrices was analyzed using a Gas Chromatography-Mass Spectrometer (GC-MS). In the raw sludge, all 16 PAHs compounds were below the standard limit except for Benzo(a)anthracene, Benzo(a)pyrene, Dibenzo(ah)anthracene, and Indeno(1,2,3- cd_ pyrene), which are considered as high rings PAHs. The high rings PAHs show lower concentration in leachate than low rings PAHs, which indicates the potential of the S/S method in remediating high rings PAHs. The high sludge ratio in S/S matrices has shown that the percentage strength is increasing, similar to Portland cement. Therefore, this study contributed to the possibility of the S/S method in the remediation of PAHs in petroleum sludge by using only Portland cement as a binder.

The disposal of industrial steel mill sludge in landfills has frequently received significant concern as the sludge has a very notable potential to contaminate soil surface and groundwater in the long run. Recently, the incorporation of industrial steel mill sludge into fired clay brick has become one of the promising alternative methods as it could produce a lightweight product while minimizing the environmental impact of the waste used. In this study, fired clay bricks as the most common building material were incorporated with 0%, 5%, 10% and 15% of steel mill sludge and fired at 1050°C (heating rate of 1°C/min). The manufactured bricks were subjected to physical and mechanical properties such as firing shrinkage, dry density, and compressive strength while the Toxicity Characteristic Leaching Procedure (TCLP) was conducted to analyze leaching behavior from the manufactured bricks. The results demonstrated that incorporation up to 15% of steel mill sludge reduces the properties up to 27.3% of firing shrinkage, 8.1% of dry density and 67.3% of compressive strength. The leaching behavior of Zn and Cu from steel mill sludge was reduced up to 100% from 7414 to 9.22 ppm (Zn) and 16436 to 4.654 ppm (Cu) after 15% of sludge incorporation. It was observed that high temperature during the firing process would improve the properties of bricks while immobilizing the heavy metals from the waste. Therefore, recycling steel mill sludge into construction building materials could not only alleviate the disposal problems but also promote alternative new raw materials in building industries.

The density, compressive strength, and thermal insulation properties of fly ash geopolymer paste are reported. Novel insulation material of glass bubble was used as a replacement of fly ash binder to significantly enhance the mechanical and thermal properties compared to the geopolymer paste. The results showed that the density and compressive strength of 50% glass bubble was 1.45 g/cm3 and 42.5 MPa, respectively, meeting the standard requirement for structural concrete. Meanwhile, the compatibility of 50% glass bubbles tested showed that the thermal conductivity (0.898 W/mK), specific heat (2.141 MJ/m3K), and thermal diffusivity (0.572 mm2/s) in meeting the same requirement. The improvement of thermal insulation properties revealed the potential use of glass bubbles as an insulation material in construction material.

In this globalized era, building materials play an essential role in the civil engineering field. Nowadays, with the increase in population, the demand for construction activities is also increasing. Polyethylene (PET) bottles are among the most widely used materials and cause an abundance of non-degradable waste, at about 0.94 million tonnes in Malaysia. One of the alternatives to reduce this waste's environmental impact is to incorporate it inside building materials such as brick and concrete. As PET bottles' recycling is highly promoted, the physical and mechanical properties of building materials made from PET bottles have also been reviewed. The data analysis shows that the compressive strength, flexural strength, split tensile strength and density of building materials decreases as the percentage of PET waste increases. However, other properties such as water absorption, initial absorption rate, and firing shrinkage increase proportionally with the PET waste. Besides, heavy metals in these building materials comply with the United States Environmental Protection Agency (USEPA) standards. It can be concluded that the percentage of PET waste incorporated into brick and concrete must be less than 5% and 2%, respectively, to produce suitable materials to provide alternatives in reducing and recycling PET waste.