A Comparative Review of Polymer, Bacterial-based, and Alkali-Activated (also Geopolymer) Binders: Production, Mechanical, Durability, and Environmental impacts (life cycle assessment (LCA))

A Comparative Review of Polymer, Bacterial-based, and Alkali-Activated (also Geopolymer) Binders: Production, Mechanical, D ...
	1 Introduction
	2 Alternative binding agents
		2.1 Polymer binders for concrete production
		2.2 Bacterial binders
		2.3 Alkali-activated materials and geopolymer binders
			2.3.1 Notes on terminology
			2.3.2 Common precursors used in alkali-activated binders
			2.3.3 Common activators used in alkali-activated binders
			2.3.4 Alkali-concentration
			2.3.5 Safety Considerations for Alkali-activated Binders
			2.3.6 Potential Applications of Alkali-activated Binders
	3 Influential parameters on alternative binding agents
		3.1 Aggregate
		3.2 Curing of alternative binding agents
	4 Fresh Properties
	5 The effect of alternative binders on mechanical properties of concrete
		5.1 Compressive strength
		5.2 Elastic modulus
		5.3 Toughness and cracking
	6 The effect of alternative binding systems on durability properties of concrete
		6.1 Porosity and its functionality
		6.2 Shrinkage
		6.3 Water absorption
		6.4 Chloride resistance
	7 The Effect of alternative binders on environmental footprint of concrete and sustainability
		7.1 Introduction to environmental footprint of binders
		7.2 Environmental footprint of polymer binders
			7.2.1 Epoxy
			7.2.2 Polyester
			7.2.3 Vinyl ester resins
		7.3 Analysis of the environmental impacts of polymer binders
		7.4 Environmental footprint of alkali-activated binders
		7.5 Environmental footprint of bacterial binders
	8 Recent research directions and research gaps in alternative binding systems
		8.1 Recent research direction in the area of polymer binder-based concrete (Polymer Resin)
			8.1.1 Manufacturing technologies
			8.1.2 Recycling of polymer resins and sustainability
			8.1.3 Hybrid Multi-functional Materials
			8.1.4 Nano and micro design of polymer resins and durability enhancements
			8.1.5 Additive manufacturing (3D Printing)
		8.2 Recent research direction in the area of bacterial concrete (or Self-healing Bio-concrete)
			8.2.1 Effectiveness of bacterial strains and healing efficiency
			8.2.2 Novel bacterial strains and applying methods
			8.2.3 Compatibility with cementitious materials and long-term efficiency
			8.2.4 Commercialization and regulatory considerations
		8.3 Recent research direction in the area of alkali-activated materials and geopolymer
			8.3.1 Environmental impact and sustainability
			8.3.2 Standardization and modeling of alkali-activated materials
			8.3.3 Uncovering reaction mechanisms of alkali-activation and geopolymerization
			8.3.4 Multi-functionality of alkali-activated materials and geopolymers in advanced digital technologies
	9 Discussion and future projections
	10 Conclusion
	Funding
	CRediT authorship contribution statement
	Declaration of Competing Interest
	Data Availability
	Acknowledgement
	References