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Additives added to the flexible pavement mixture aim to increase the strength of the pavement. Limestone which is a sedimentary rock consists of the mineral calcium carbonate (calcite) or the double carbonate of calcium and magnesium (dolomite). The use of limestone in pavement mixtures is expected to increase the performance of Marshall parameters. This study aims to determine the suitability of limestone as a filler for 3 types of pavement mixtures, namely Asphalt Concrete Wearing Course, Hot Rolled Sheet and Split Mastic Asphalt. In this study, the limestone used was sourced from Jorong Durian, Nagari Kamang Mudiak, Kamang Magek District, Agam Regency, West Sumatra Province. The tests were carried out using following variations of limestone; 0%, 25%, 50%, 75%, 100% of the total amount of filler in the mixture. The results of the study using limestone as filler obtained at an optimum content of 29% for AC-WC, 22% for HRS, and 82.5% for SMA. In addition, AC-WC pavement was found to the best increase in Marshall stability performance. Therefore, it can be concluded that limestone from Kamang Mudiak is most suitable to be added to AC-WC pavement mixtures.

Due to inadequate crude oil supply and a rising demand for petroleum asphalt in roadconstruction, the asphalt sector faces a continuing shortage. Continous research was conducted on renewable materials such as bio-oils derived via pyrolysis from local palm oil industries. Bio-oil is currently a viable option due to its renewability, environmental friendliness, and variety of sources. Despite numerous studies indicating that biooils enhance the properties of bitumen, the research on the effects of PKS biooil on bitumen properties is minimal and needed further investigations. The application of 2,4-diphenylmethane diisocyanate (MDI) in this study is established to enhance the properties of bio-oil modified bitumen. The objectives of this study are to analyse the relationship between the percentage andratio of PKS bio-oil and 2,4-diphenylmethane diisocyanate (MDI) of the modified bitumen, its physical and chemical effects and the optimization of bio-asphalt mixture after the 2,4diphenylmethane diisocyanate (MDI) has been blended with PKS bio-oil and bitumen. PKS bio-oil and MDI were applied into the bitumen as additive and replacement of bitumen at 3%, 5% and 7% with two different ratios; 1.0:0.6 and 1.0:1.0. The functional groups of the bitumen are identified using Fourier Transform Infrared (FTIR) analysis. The result generated from FTIR analysis showed that the modified bitumen samples were slightly different when compared to the conventional bitumen regarding the functional group. Response surface methodology (RSM)was implemented to determine the statistical analysis and optimum amount of PKS bio-oil and MDI content in the bitumen, through central composite design.

The presence of heavy metals affects the properties of soil due to a decrease in the dielectric constant, which increases the risk of contamination. Current conventional treatments are costly, slower, and environmentally unsustainable. Therefore, soil biocementation improvement using enzymatically induced calcium carbonate precipitation has gained attention due to its cost-effectiveness, sustainability, and environmental friendliness. This study investigates the effect of this technique on the retention and immobilization of heavy metal-contaminated mine waste sourced from Lohan Dam, Sabah, Malaysia, under different curing periods (1 and 3 days), degrees of compactions (70 and 80% of the maximum dry density), and curing temperatures (5 °C, 15 °C, and 25 °C) but at constant 1.0M cementation solution using inductively coupled plasma-optical emission spectrometry, acid washing test, and scanning electron microscopy. Results indicate that the treatment effect is immediate and able to increase the retention of heavy metals in the order of Ni> Cu > Pb, with the highest retention observed at 25 °C and higher retention at lower degrees of compaction. SEM images confirm the formation of calcite in soil particles. In conclusion, the optimum treatment conditions for a 1.0 M EICP cementation solution are 25 °C, 70% MDD, and 1-day curing.

It is not uncommon for mining activity to generate wastes associated with negative engineering impacts include susceptibility to runoff due to the absence of vegetation, erosion, and sinkhole. Due to their high degree of permeability, movement of heavy metal contaminants in waste soils and aquifers occurs actively along with the hydrogeological parameters, and research on using biocementation methods such as enzyme induced calcite precipitation (EICP) to reduce the hydraulic conductivity is therefore beneficial. Mine waste soil collected from a copper mine in Lohan Dam, Sabah is characterized physically, morphologically, and chemically then treated with EICP under different operational parameters include curing duration (1,3,7 days), curing temperatures (5, 10, and 25 oC ), and relative density (70 and 80 %). The hydraulic conductivity was then tested using a constant head permeability test and the calcium carbonate content (%) is determined using the HCL washing method. Properties of the Lohan Dam wastes are found to be predominantly coarse grain soil of low plasticity, high specific gravity, high permeability, acidic in nature, and low organic content. Morphologically, they are composed of powdered and hardened particles with dark brown color with high amount of irregular-shaped particles. Mineralogical, Lohan Dam soil wastes contain a high level of heavy metals beyond the safety level of the Department of Environmental Malaysia. EICP treatment had to change the degree of permeability from ‘high and medium’ to ‘low’ with a 94-97% reduction in hydraulic conductivity corresponding to the amount of calcium carbonate content produced ranging 6.94-9.63%. In conclusion, relative density shows the marginal effect, curing duration, and temperature shows a more significant impact on the treatment effectiveness.

Mining wastes are known to be harmful to the environment especially when unregulated, untreated, or abandoned. The first step in their remedial action is the characterization of the geotechnical properties. The aim of this research is to investigate the properties of two Copper mine wastes obtained from Lohan and Bongkud in Sabah, Malaysia, for potential biocementation treatment. The methodology includes soil classification, determination of engineering properties, geochemical properties, and microstructure fabric. Classification results indicated that while both soils can be classified as SM and A-4 according to USCS and AASHTO respectively, Lohan waste has higher coarse-grained particles (69.8%) compared to Bongkud (58.1%). Both soils have a low liquid limit (LL<50), low plasticity (PI <7) and low liquidity (LI<1), and a close range of specific gravity (2.65-2.71). However, Bongkud has higher pH (5.27) and natural moisture content (28.14%) due to its higher organic content (1.27%). In terms of engineering properties, Lohan and Bongkud have MDD at 1640 and 1700 kg/m³ and OWC at 16 and 15%, respectively, with low cohesiveness and a high angle of friction. With hydraulic conductivity, k falls within the range of 10-2 cm/s, and these soils are classified as having a medium degree of permeability. Geochemical analysis indicated the presence of nine heavy metal elements with Pb (0.535 mg/L) and Ni (1.092 mg/L) exceeded the safety level in Lohan and Bongkud, respectively. SEM analysis shows both soils have a high degree of disorientation. In conclusion, both soils can be benefitted from biocementation treatment due to the SM classification, medium degree of permeability, and high heavy-metal contaminations. [ABSTRACT FROM AUTHOR]

Most of the road constructions in Riau Province are built on problematic and poor peat soil that resulted in the roads in this province do not last long according to their design. The aim of this research is to improve the engineering properties of the peat soil obtained from Rimbo Panjang, by using lightweight materials such as Bagasse and Sawdust Ash mixed with Portland Cement so that they meet the conditions stipulated as subgrade for road pavement layer. The tests conducted include determination of the physical properties of the peat soil such as Moisture Content, Organic Content, Ash Content, Unit Weight, Specific Gravity, Atterberg Limit and Dry Density, and engineering properties such as CBR and Unconfined Compressive Strength. A total of 18 CBR and 24 Unconfined Compressive Strength samples were prepared and tested. Results obtained showed the increases in the Dry Density, CBR value, and Unconfined Compressive Strength value. The highest increment is observed on peat soils that mixed with 15% Cement with Unconfined Compressive Strength of 92 kN/m2, Dry Density of 0.53 gr/cm3, and CBR value of 4.67 %. It is followed by peat soils that mixed with 15% Cement and 30% Bagasse Ash with Unconfined Compressive Strength of 90 kN/m2, Dry Density of 0.5 gr/cm3, and CBR value of 4.56%. It can be concluded that Bagasse Ash shows a better result than Sawdust Ash in stabilizing Rimbo Panjang peat soils. [ABSTRACT FROM AUTHOR]