sustainability Article Sustainable Valorisation of Silane-Treated Waste Glass Powder in Concrete Pavement Mazen J. Al-Kheetan 1 , Juliana Byzyka 2, * and Seyed Hamidreza Ghaffar 3   Citation: Al-Kheetan, M.J.; Byzyka, J.; Ghaffar, S.H. Sustainable Valorisation of Silane-Treated Waste Glass Powder in Concrete Pavement. Sustainability 2021, 13, 4949. https:// doi.org/10.3390/su13094949 Academic Editor: Edoardo Bocci Received: 23 March 2021 Accepted: 26 April 2021 Published: 28 April 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). 1 Civil and Environmental Engineering Department, College of Engineering, Mutah University, Mutah, P.O. Box 7, Karak 61710, Jordan; mazen.al-kheetan@mutah.edu.jo 2 Civil Engineering Department, School of Science, Engineering and Environment, University of Salford, Newton Building, Crescent, Salford M5 4NT, UK 3 Department of Civil and Environmental Engineering, College of Engineering, Design and Physical Sciences, Brunel University London, Kingston Ln, Uxbridge, Middlesex UB8 3PH, UK; seyed.ghaffar@brunel.ac.uk * Correspondence: j.byzyka@salford.ac.uk Abstract: This research presents new insights into the utilisation of waste glass powder in concrete pavements. Two different types of glass powder were used as a partial replacement for sand: 10% neat glass powder (untreated) and 10% silane-treated glass powder. The interfacial bonding properties, physical properties, and mechanical properties of concrete pavement were assessed at 7 and 28 days. Results exposed a reduction of 5% and 2% in the compressive and flexural strengths, respectively, and an increase of 15% in water absorption after the addition of neat glass powder to concrete after 7 days of curing. This is due to weak interfacial bonding between the glass powder and cementitious matrix. However, the incorporation of silane-coated glass powder led to an increase in the compressive and flexural strengths by more than 22% and 28%, respectively, and reduced the water absorption of concrete by 8%, due to the coupling functionality of silane. After 28 days of curing, the compressive strength of concrete increased by 15% and 22% after the addition of neat glass powder and silane- treated glass powder, respectively. In addition, water absorption dropped by 5% and 7% after the incorporation of neat glass powder and silane-treated glass powder. Keywords: glass powder; sustainable development; concrete; silane; morphology; strength 1. Introduction The sustainable construction concept emerged two decades ago to ensure green de- velopment in the construction industry and to guarantee efficient use of resources in the industry [1–4]. However, the rise of sustainable construction involved many challenges throughout the design, management, implementation, operation, and maintenance phases of construction projects [1–6]. Moreover, moving toward sustainable construction, a signifi- cant challenge in material selection and valorisation was created, where the construction sector consumes more than 60% of natural resources as building materials [2,7–9]. Concrete is one of the construction materials that consumes more than 20 billion tonnes of raw material every year [10]. Aside from the high consumption of raw materials in the concrete production process, the manufacturing of its main constituent, cement, accounts for more than 80% of the total CO 2 emissions from concrete production [11–14]. Additionally, the production of coarse and fine aggregates is responsible for the other 20% of CO 2 emissions from concrete production [11,15]. As a result, researchers started to explore other alterna- tives, either by replacing cement and aggregate with environmentally friendly materials, or by replacing them with recycled materials [16–20]. In recent years, more research, considering the influence of highway construction on the environment, started to emerge, which highlighted its vulnerability and the environ- mental risks that pavement construction imposes on the ecosystem after the deterioration of pavements [21]. Therefore, the sustainable construction of highways has recently arisen Sustainability 2021, 13, 4949. https://doi.org/10.3390/su13094949 https://www.mdpi.com/journal/sustainability