Case study A comparative assessment of the physical and microstructural properties of waste garnet generated from automated and manual blasting process Kabiru Rogo Usman a,c , Mohd Rosli [107_TD$DIFF]Hainin a,b, *, Mohd Khairul Idham [108_TD$DIFF]Mohd Satar a , Muhammad [109_TD$DIFF]Naqiuddin Mohd Warid a , Aliyu Usman d , Zaid Hazim Al-Saffar a , Munder Abdullah Bilema e a School of Civil Engineering, Universiti Teknologi Malaysia, 81310, Johor Bahru, Johor, Malaysia b University Malaysia Pahang, 26600, Pekan, Pahang, Malaysia c Department of Civil Engineering Technology, School of Engineering Technology, Nuhu Bamalli Polytechnic Zaria, P.M.B 1016, Zaria, Kaduna State, Nigeria d Civil and Environmental Engineering Department, University Teknologi PETRONAS, Bandar Seri Iskandar, Perak, 32610, Malaysia e Department of Civil Engineering, Faculty of Engineering, Benghazi University, Benghazi, Libya ARTICLE INFO Article history: Received 3 September 2020 Received in revised form 21 November 2020 Accepted 11 December 2020 Keywords: Cold mix asphalt Automatic generated spent garnet Manually generated spent garnet Fine aggregate replacement Heavy metals Leachate ABSTRACT Cold mix asphalt (CMA) is an eco-friendly sustainable asphalt mixture, mostly for asphalt surface treatments (ASTs). However, material compatibility and poor adhesion leading to high voids, moisture damage susceptibility, and weak early strength remain challenging. Efforts to solve this limitation is beamed towards binder improvement and modification with modifiers, adhesion promoters, or polymers. Other forms of AST mixture improvement entail supplementary cementitious reinforcing or pozzolanic agents in the form of by-products. In this study, the physio-mechanical and microstructural desirability of spent garnet for use as fine aggregate in CMA was explored. Spent garnet is a by-product of abrasive blasting, often produced in large quantities and disposed of in landfills. Often, spent garnet waste gets contaminated with toxic elements either during usage or in landfills.ThisstudyaimedtoinvestigatethepropertiesofAutomatically(AG)andManually generated (MG) spent garnet grades. The physio-mechanical, morphologic, and chemical parameters of spent garnet were assessed to achieve this aim. The result compared with relevant specifications on cold mixtures plus Jabatan Kerja Raya (JKR) requirement. Moreover, crystallinity and composition were studied using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction(XRD), and X-ray Fluorescence (XRF). The presence of toxic heavy metals that often contaminate spent garnet deposits in landfills was evaluated too. Results suggested that both AG and MG’s high sand equivalent and least water absorption of 98 %, 89 %, and 0.14 %, 0.23 % accordingly, and can replace sand in CMA. However,MGspentgarnetisnotdesirableforchemicallysensitivematerials.TheAGgarnet was found to be Pyrope while the MG spent garnet is largely Almandine garnet – the strongest form of garnet, including traces of other garnet forms. © 2020 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). * Corresponding author at: School of Civil Engineering, Universiti Teknologi Malaysia, 81310, Johor Bahru, Johor, Malaysia. E-mail addresses: mrosli@utm.my, roslihainin@ump.edu.my (M.R. [107_TD$DIFF]Hainin). https://doi.org/10.1016/j.cscm.2020.e00474 2214-5095/© 2020 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/). Case Studies in Construction Materials 14 (2021) e00474 Contents lists available at ScienceDirect Case Studies in Construction Materials journal homepage: www.elsevier.com/locate/cscm