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Sewage sludge as sustainable resource for lightweight aggregate

Event organised by ICE

08 September 2022

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Concrete is the most widely used construction material and, due to its high utilization, has led to the depletion of natural resources, such as conventional aggregates. Many countries in the world are also facing a shortage of high-quality natural aggregates to support local construction needs. Researchers in the construction industry have been developing a more sustainable approach in order to mitigate this issue. One such approach is the reuse of different solid waste materials including sewage sludge, oil-palm-boiler waste, oil palm shell (OPS), palm oil fuel ash (POFA), Ground Granulated Blast-furnace Slag (GGBS), Metakaolin, RHA, tires, and fly ash to produce artificial lightweight aggregates (LWA).

Two major forms, natural LWA and artificial LWA, can be grouped into LWA. The primary source for natural LWA, such as pumice and scoria, is volcanic origin. Artificial LWA, on the other hand, can be produced by thermal treatment of natural materials, industrial by-products, waste materials, etc.

Sewage sludge is an unavoidable by-product of wastewater treatment and can be abundantly found in all over the world. Insufficiencies of landfill sites and rigorous environmental regulations have created disposal problems of sludge. Most of the sludge is disposed of by landfilling and spreading on agricultural land as a fertilizer. All these disposal methods are directly related to the environmental impact such as air, river, sea and groundwater pollution. Studies have been carried out by many researchers to investigate the promising use of sludge and sludge ash as sustainable construction materials. The reuse of sewage sludge into construction materials not only improves disposal problems but also has economic, ecological and energy-saving advantages.


Dr Muhammad Rahman

Dr Muhammad Rahman

Engineers Australia

fellow and chartered professional engineer

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Dr Muhammad Rahman

Dr Muhammad Rahman received his PhD from the University of Dublin, Trinity College, Ireland. He is an active researcher with a significant number of papers in peer reviewed Q1 journals. He has a wide range of research interests, both of a fundamental and an applied nature, particularly in the areas of sustainable construction materials, computational structural mechanics, composite materials, energy, retrofitting and slope stabilization. Prior to his current appointment at Northumbria University UK, he served as a senior faculty member, Head of Department and Head of Materials & Structures Research Cluster at Curtin University, Malaysia.

He received eleven external grants from the Ministry of Higher Education, Malaysia and industry, and supervised three MPhil & seven PhD students and one post-doctoral research fellow. He was awarded the IMM Green Materials Award from the Institute of Materials Malaysia. He also had significant industrial experience in Dublin, Ireland. He is a Fellow of ICE and a Fellow and Chartered Professional Engineer with Engineers Australia. He is a member of the Nature group's scientific reports editorial board.

Professor Abdul Mannan

Professor Abdul Mannan



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Professor Abdul Mannan

Professor Abdul Mannan obtained BSc in Civil Engineering with First Class in 1986 (Rajshahi University, Bangladesh), MSc in 1994 (UKM, Malaysia) and PhD in 2001 (UMS, Malaysia). He started his career as lecturer at Bangladesh Institute of Technology, Rajshahi (now RUET) in 1986. He served as design engineer at AJP, consulting firm, Kuala Lumpur, Malaysia from 1994 to 1998 to design several structural and infrastructural projects including 25-storey Tower and RM60million infra. project. He served as academician at University Malaysia Sabah, UMS for 13 years (1999 to 2012). Now, he is at University Malaysia Sarawak, UNIMAS, Malaysia since May 2012.

Based on 36 years of experience in teaching, professional practice and research, his vision is to be excellent in research on Innovative Construction Material and Structure. He has supervised several PhD students, received several gold medals for his research work, and received several external grants. He has served on the Ministry's technical panel for research grants. He is an ICE Fellow.

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Joanne Topping