Strength, porosity and life cycle analysis of geopolymer and hybrid cement mortars for sustainable construction

• Published in: The Science of the total environment Vol. 907; p. 167839
• Main Authors: Raza, Muhammad Huzaifa, Khan, Mahram, Zhong, Ray Y.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 10.01.2024
• Subjects: Environmental impact; Geopolymers; Hybrid cement mortars; Life cycle analysis; Sustainable construction; Hybrid cement mortars; Geopolymers; Sustainable construction; Environmental impact; Life cycle analysis
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2023.167839

Owing to the application of industrial wastes, geopolymers are generally regarded as a sustainable alternative to traditional construction materials. However, their lack of adoption on the industrial scale demands detailed investigations. This study conducts a comparative analysis of the compressive strength of different geopolymer and hybrid cement mortars with varying proportions of sodium hydroxide (from 5 to 25 wt%) and ordinary Portland cement (OPC) (from 15 to 35 wt%), respectively. The porosity of all designed mixtures was also analyzed using X-ray computed tomography (XCT) and water absorption tests. ReCiPe 2016 Midpoint (H) method was used for the Life cycle analysis of the geopolymer and hybrid cement mortars. Multi-criteria decision making (MCDM) approach was used to assess the sustainability potential of the designed mixtures based on compressive strength, porosity and overall environmental impact. Experimental results revealed that the increase in sodium hydroxide in geopolymer mortars up to 15 wt% offered its maximum compressive strength. Superior compressive strength was obtained at 35 wt% of OPC in hybrid cement mortars due to the formation of more C-S-H, C-A-S-H and N-A-S-H gels which fill up the voids and pores. Analysis of the macro and micro-porosity revealed that hybrid cement mortars yield denser structure than geopolymer mortars. Life cycle analysis based on 8 distinct impact categories showed that hybrid cement mortars outperform the geopolymers in all impact categories except ‘mineral resource scarcity’. However, the overall environmental impact assessment using the ‘coefficient of performance’ depicts that hybrid cement mortars offer a significantly lower environmental burden than geopolymers. MCDM analysis shows that hybrid cement mortar with 5 wt% of sodium hydroxide and 35 wt% of OPC is the best choice for construction applications. This idea of sustainable hybrid cement mortar will be helpful for the construction industry to limit the environmental impact without compromising their structural performance. [Display omitted] •Comparative sustainability analysis of geopolymer and hybrid concretes with varying proportion of NaOH and OPC respectively.•To analyze the 180-day compressive strength, the impact of NaOH and OPC on mechanical properties of various mortars materials was assessed.•Analysis of porosity of different geopolymer and hybrid cement mortars through XCT and water absorption.•Cradle to gate life cycle analysis performed to investigate the environmental sustainability of different materials.