Md. Maniruzzaman A. Aziz

Potentials of steel slag and copper mine tailings as construction materials

Abstract The present rate of utilisation of mine waste in a country like Malaysia is rather below expectation compared with some advanced countries. Many studies concentrate on a better way to increase the usage of industrial byproducts in order to ease disposal problems. Enormous quantities of steel slag and copper mine tailings are deposited in yards, polluting the environment. Researchers need to pay attention to the effective use of industrial byproducts in construction to address economic and environmental concerns. The potential uses of copper mine tailings and steel slag need to be explored and the negative impact of mine tailings should be reduced by exploring potential uses of these waste materials in the construction industry. Although copper tailings have negative effects on the environment owing to their acidic content, they also have some great economic value in terms of valuable metal contents. The engineering properties of steel slag and copper mine tailings were reviewed and their various areas of application are highlighted.

Characterisation and utilisation of steel slag for the construction of roads and highways

Abstract Steel slags are by-products from steel industries which can be used for the construction of roads and highways. Most of the physical and mechanical properties of steel slags are similar or better compared to conventional crushed stone aggregates. Most of the developed countries have successfully incorporating steel slags as an aggregate in hot mix asphalt, road base, sub-base and soil stabilisation in road works. This paper is a review of the physical, mechanical and chemical characteristics of steel slags and its utilisation in road pavement works. This paper highlights the flaws that need to be addressed, and further studies are required to develop an understanding of the potential of steel slag as a construction material. Hydrophobic property of steel slag provides a good adhesion with bitumen binder and helps to resist against the stripping and other defects of roads. Thus, it enhances a sustainable cost-effective green pavement in highway industry.

Effect of Aging on the Resilient Modulus of Stone Mastic Asphalt Incorporating Electric Arc Furnace Steel Slag and Copper Mine Tailings

Currently, the cost of production of stone mastic asphalt (SMA) is relatively high for paving roads and highways. One means of reducing the cost is to use relatively low cost by-products as aggregates and fillers. The main purpose of this study is to appraise the effect of aging on resilient modulus of SMA incorporating electric arc furnace (EAF) steel slag and copper mine tailing (CMT) as binary industrial waste materials. To achieve this aim, four mix designs consisting of EAF steel slag and CMT at various percentages were investigated. Marshall stability, drain down and indirect tensile resilient modulus tests were conducted. The indirect tensile resilient modulus test was carried out to assess the stiffness of SMA mixture at 25 and 40 °C. Stiffness variation in asphalt mixtures play a vital role in inflicting cracking and rutting in pavement. While some samples were unaged, equal numbers of samples were subjected to short term and long term oven aging. The results show that incorporating EAF steel slag and CMT into SMA mixture has a substantial positive effect on the drain down and resilient modulus of SMA. Thus, the study has contributed to the reuse of economical and environmentally friendly metallurgical and mining by-products in roads and highway industries.

Performance of warm-mix asphalt in the highway industry

Abstract Warm-mix asphalt (WMA) technologies could address the problem of deterioration of roads, reduce escalated energy costs and increase environmental awareness. This technology allows significant reduction in temperature for construction and paving of roads compared to conventional hot-mix asphalt (HMA) paving. In HMA production, the quarry mixing and paving temperatures are equivalent to bitumens viscosity of 170 and 280 cP, respectively, for a proper coating of aggregates and field paving. But in WMA, the viscosity of bitumen is reduced and increases the workability of the mixture. Sasobit and asphamin are the two major additives used with bitumen or in batching plant for the production of WMA. Besides, complex shear modulus (G*) is used to determine the rutting (G*/Sinδ) and fatigue factors (G*Sinδ) to control the deterioration of roads. A further study is needed to monitor the overall performance of WMA in the context of pavement temperature.

Performance of Kaolin Clay on Hot-mix Asphalt Properties

Kaolin clay is a waste product with numerous applications in construction. This study explored the addition effect of kaolin clay on the properties of hot-mix asphalt. Four replacement levels of kaolin clay were considered by weight of binder, i.e., 2%, 4%, 6%, and 8%. The performance of kaolin clay on the hot-mix asphalt was evaluated through a Marshall stability and flow test, including stiffness, density, voids in total mix, and voids in filled with asphalt. Test results showed that kaolin clay can be satisfactorily used as filler replacement material to increase the asphalt mixture properties. Generally, asphaltic concrete with 2% kaolin clay replacement level exhibits excellent performance with good stability and stiffness.

Optimisation of a modified submerged bed biofilm reactor for biological oleochemical wastewater treatment

Oleochemicals industry effluence mainly contains a high chemical oxygen demand (COD) in a range of 6000-20,000 ppm. An effective biological wastewater treatment process must be carried out before wastewater is discharged into the environment. In this study, a submerged bed biofilm reactor (SBBR) was adapted to the biological oleochemical wastewater treatment plant observed in the present study. The effect of wastewater flow rate (100-300 mL/min), Cosmoball® percentage in the SBBR system (25-75%), and percentage of activated sludge (0-50%) were investigated in terms of COD reduction. The Box-Behnken design was used for response surface methodology (RSM) and to create a set of 18 experimental runs, which was needed for optimising the biological oleochemical wastewater treatment. A quadratic polynomial model with estimated coefficients was developed to describe COD reduction patterns. The analysis of variance (ANOVA) shows that the wastewater flow rate was the most effective factor in reducing COD, followed by activated sludge percentage and Cosmoball® carrier percentage. Under the optimum conditions (i.e., a wastewater flow rate of 103.25 mL/min a Cosmoball® carrier percentage of 71.94%, and an activated sludge percentage of 40.50%) a COD reduction of 98% was achieved. Thus, under optimum conditions, as suggested by the BBD, SBBR systems can be used as a viable means of biological wastewater treatment in the oleochemicals industry.

Thin cold-mix stone mastic asphalt pavement overlay for roads and highways

Abstract This paper presents the latest development in the design of thin cold-mix stone mastic asphalt (SMA) pavement using modified bitumen emulsion that addresses the topmost global issues, environmental pollution and energy crisis. The hot-mix asphalt (HMA) pavement is generally known to have higher strength and is more durable compared to others, but have some disadvantages on environment, economy and safety-related issues. Cold-mix asphalt (CMA) pavements are widely used because of its simple technique and easy to construct. Currently, there are no established standards and specifications of mix design for CMA, especially for gap-graded pavement in Malaysia, and the laboratory test results are inconsistent. The use of 4·75mm nominal maximum aggregate size (NMAS) for the HMA has the highest potential for preventive and reactive maintenance of roads. Further study is needed to design and develop 4·75mm NMAS cold-mix SMA pavement in order to achieve and produce a cost-effective sustainable pavement.