A mixture of sewage sludge and red gypsum as an alternative material for temporary landfill cover

This study proposed the recycling of sewage sludge (SS) and red gypsum (RG) as potential temporary landfill cover materials. Mixtures with different SS and RG compositions were prepared and tested in determining the most suitable design mix based on the resulting physical, mechanical, and geotechnic...

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Bibliographic Details
Published in:Journal of environmental management 2020-06, Vol.263, p.110420-110420, Article 110420
Main Authors: Rosli, Nor Azalina, Aziz, Hamidi Abdul, Selamat, Mohamad Razip, Lim, Leonard Lik Pueh
Format: Article
Language:English
Subjects:
Compressive strength
Hydraulic conductivity
Landfill cover
Plasticity
Red gypsum
Sewage sludge
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Summary:This study proposed the recycling of sewage sludge (SS) and red gypsum (RG) as potential temporary landfill cover materials. Mixtures with different SS and RG compositions were prepared and tested in determining the most suitable design mix based on the resulting physical, mechanical, and geotechnical properties, namely the hydraulic conductivity, compressive strength, and plasticity. A maximum compressive strength of 524 kPa was achieved for the optimum SS:RG composition of 1:1, corresponding to Ca:Si composition of 2.5:1, which was appropriate to form the calcium silicate hydrate (CSH) gel. The SS and RG compositions did not affect the hydraulic conductivity, which was in the order 10−5 cm/s for all mixtures. Mixtures with RG greater than SS in composition exhibited plastic behaviour due to the Fe content in the RG, which helped minimize the risk of cracking. The optimum mixture had compressive strength greater than the specified minimum of 345 kPa, medium hydraulic conductivity, and moderate plasticity, thus appropriate for application as an alternative material for the temporary landfill cover in the tropics. •A mixture of sewage sludge (SS), and red gypsum (RG) as temporary landfill cover was investigated.•Optimum mix at SS:RG ratio of 1:1 achieved 345 kPa and 10−5 cm/s.•SS:RG ratio of 1:1 corresponded close to Ca:Si ratio of 2.5:1for hydration to form CSH gel.•Fe in RG contributed to the plastic behaviour of the mix.•SS:RG ratio of 1:1 is appropriate for application as a temporary landfill cover material.
ISSN:0301-4797
1095-8630
DOI:10.1016/j.jenvman.2020.110420