Affiliations 

  • 1 Faculty of Engineering, Universiti Malaysia Sarawak, 94300, Kota Samarahan, Malaysia; School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300, Nibong Tebal, Pulau Pinang, Malaysia. Electronic address: [email protected]
  • 2 School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300, Nibong Tebal, Pulau Pinang, Malaysia; Solid Waste Management Cluster, Engineering Campus, Universiti Sains Malaysia, 14300, Pulau Pinang, Malaysia. Electronic address: [email protected]
  • 3 School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300, Nibong Tebal, Pulau Pinang, Malaysia; Solid Waste Management Cluster, Engineering Campus, Universiti Sains Malaysia, 14300, Pulau Pinang, Malaysia. Electronic address: [email protected]
  • 4 Faculty of Engineering, Universiti Malaysia Sarawak, 94300, Kota Samarahan, Malaysia. Electronic address: [email protected]
J Environ Manage, 2020 Jun 01;263:110420.
PMID: 32883483 DOI: 10.1016/j.jenvman.2020.110420

Abstract

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.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.