Advances in geopolymer materials: A comprehensive review

Geopolymer is a new environment-friendly cementitious material, and the development of geopolymer can reduce the carbon dioxide emission caused by the development of cement industry. Geopolymer materials not only have excellent mechanical properties, but also have a series of excellent properties such as fire resistance and corrosion resistance. Most industrial solid waste and waste incineration bottom ash are piled up at will, which not only occupies land resources, but also has a bad impact on the environment. Recycling them can be used as raw materials for preparing geopolymers. Geopolymer materials can effectively adsorb heavy metals, dyes, and other radioactive pollution, which is very beneficial to society's future development. However, due to the excellent properties of geopolymer materials, its application goes beyond that. Some useful information about geopolymer materials was introduced in this paper. The paper included the geopolymerization, the source of raw materials, the types of activators, the preparation methods, and the different application fields of geopolymer materials. The factors affecting the fresh properties and mechanical properties of geopolymer materials were discussed. In this paper, the shortcomings and application limitations of geopolymer materials were summarized, and their progress was summarized to lay a theoretical foundation for the long-term development of geopolymer materials.

Comparison and assessment of carbon dioxide emissions between alkali-activated materials and OPC cement concrete

Geopolymer concrete(GPC)has been developed as a sustainable alternative to traditional cement-based concrete using industrial waste materials.Thus,reducing greenhouse gas emissions in concrete production can be expected.This study employed the life cycle assessment(LCA)method to evaluate geopolymer concrete's cost and life-cycle carbon dioxide(CO_(2))emissions.Moreover,the critical transportation radius of the geopolymer is estimated.Then,evaluation results were compared with ordinary Portland cement(OPC),considering three concrete construction methods:cast-in-place,ready-mixed,and precast.In particular,the service life of two types of concrete in sulfuric acid environments is considered.Compared with OPC concrete,the results show that geopolymer concretes can significantly reduce the cost and CO_(2)emissions when one or a small amount of alkali activator is used or alkali-containing materials are used to replace some alkali activators.However,the advantages would be reversed by the rising alkali dosages,which account for cost increases and carbon emissions.When considering the service life in special environments,geopolymer concrete in sulfuric acid environments corresponds to fewer carbon emissions,94%-97%decreased compared with OPC concrete.Finally,compared with OPC concrete,the newly developed limestone calcined clay cement(LC3)avoids high-temperature calcination and dramatically reduces carbon dioxide emissions.Compared to OPC concrete,LC3 concrete has a 19%reduction in CO_(2) emissions.And geopolymer concrete that takes alkali-activate materials for superseding alkalis also produces less carbon dioxide emissions.In particular,CO_(2) emissions from FA-SF geopolymer concrete are approximately 50%lower than OPC concrete.In addition,the use of alkali activators significantly weakens the cost advantage of geopolymers.But after accounting for waste disposal costs,the average net cost of fly ash-based geopolymer concrete can be more than 30% lower than that of OPC concrete.The average net cost of slag-based geopolymer concrete is 7%-45%lower than that of OPC concrete.The findings of this work provide the basis for further development of geopolymer concretes obeyed environmental protection.