Development of expansive soil geopolymer binders for use in waste containment facility
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TECHNICAL PAPER
Development of expansive soil geopolymer binders for use in waste containment facility Jonah Chukwuemeka Agunwamba1 · Michael Ebie Onyia1 · Donald Chimobi Nwonu1 Received: 4 August 2020 / Accepted: 1 November 2020 © Springer Nature Switzerland AG 2020
Abstract Waste containment facilities require liners and covers for safe waste disposal, which can be efficiently achieved using robust green technologies. In the present study, a systematic approach was adopted towards the development of reliable expansive soil geopolymers suitable for waste containment application. Various factors that influence geopolymerisation were considered including the precursor type (PT), precursor content, liquid alkali hydroxide type (LT), activator-to-precursor ratio (A/P) and method of preparation. Multiresponse optimisation for permeability, volumetric shrinkage and unconfined compressive strength was executed to achieve soil geopolymers that satisfy the regulatory requirement as hydraulic barrier materials. This was done using a robust experimental design and the utility concept to prescribe a framework for achieving reliable soil geopolymers. The results obtained show that significant interactions between the factors (PT × LT) and (PT × A/P) affected the response characteristics and consequently the soil geopolymer performance. The aptness of the multiresponse optimisation was confirmed at 95% confidence interval, which revealed that the developed soil geopolymers can be used in waste containment facility under certain conditions. Evidence of the geopolymerisation process was clarified using microstructural analyses. Scanning electron microscopy and energy-dispersive spectroscopy supported the formation of N–A–S–H and K–A–S–H gels. Moreover, diffraction patterns for new minerals such as muscovite and crystobalite were formed, with the disappearance of clay minerals. The presence of aluminosilicate gel binding systems was revealed by Fourier transform infrared spectroscopy. The participation of clay minerals in the geopolymerisation distinguishes the developed expansive soil geopolymer from the conventional geopolymers developed for concrete applications. Keywords Expansive soil · Geopolymer · Microstructure · Palm oil fuel ash · Quarry fines · Waste containment
Introduction In geoenvironmental practice, the use of hydraulic barrier materials is conventional for the containment of various wastes (which could be in the form of municipal solid waste, industrial effluent or other hazardous materials). Safe disposal of the various wastes is intended to be expediently done through landfill disposal systems, specially constructed and lined with liner and cover materials. The production of * Donald Chimobi Nwonu [email protected] Jonah Chukwuemeka Agunwamba [email protected] Michael Ebie Onyia [email protected] 1
Civil Engineering Department, University of Nigeria, Nsukka 410001, Enugu State, Nigeria
various wastes has surged lately due to increased urbanisation, industrialisation and poor envir
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