Investigation of sulfates effects in perlite‐based geopolymer

Abstract

Condition deterioration of the concrete, especially in corrosive environments, is one of the most common imperfection and disadvantages of reinforced concrete structures. Sulfates' main damages are expansion and loss of strength. Geopolymers are one of the newest structural materials that have been widely developed in recent years for use in sustainable designs. Geopolymers are environmentally friendly and considered as green materials since they are effective in sustainable and eco‐friendly material design concept. One of the most important matters in the sustainability of structural materials is their resistance against sulfates. So far, the durability of perlite‐based geopolymers against sulfates and acids has not been investigated. In this research, the fineness influence, curing conditions, duration of maintaining in the sulfate environment at different weight percentage in solution (i.e., 2.5, 5, 7.5, and 10%) have been investigated. Compressive strength and microstructure changes of geopolymer samples have been assessed in this research. As a result, optimum increase in perlite fineness causes increase in compressive strength and durability of samples against sulfate attack. Also, samples that have been cured by autoclave method have better mechanical properties and better durability. It is hoped that by filling these deficiencies and gaps, a positive step can be taken to accelerate attempts for finding a suitable replacement for ordinary Portland cement.

Strength Development and Durability of Metakaolin Geopolymer Mortars Containing Pozzolans under Different Curing Conditions

“…It generally contains more than 70% silica and can be used in plaster, concrete, mortar, and ceiling flooring [23,24]. When heated up to 800-1150 • C, its volume increases by 10-30% and turns into low-density, high-heat-resistant, and white-colored expanded perlite (EP) [25,26]. EP is used as a heat and sound insulation material in the construction industry [26,27].…”

“…Recent studies have shown that ground calcined perlite (GCP) can be used in the production of geopolymers [26,27]. Increasing perlite fineness improves the compressive strength of geopolymer and chemical resistance to aggressive environments [1,25]. In general, fine perlite reduces pores in geopolymer, creates a more compact structure, and provides more strength [27].…”

“…In general, fine perlite reduces pores in geopolymer, creates a more compact structure, and provides more strength [27]. The mechanical properties of geopolymers can be enhanced by increasing the curing temperature and duration as well as the activator molarity [23][24][25][26][27]. The addition of kaolin or metakaolin improves mechanical properties [25].…”

“…The mechanical properties of geopolymers can be enhanced by increasing the curing temperature and duration as well as the activator molarity [23][24][25][26][27]. The addition of kaolin or metakaolin improves mechanical properties [25]. However, compressive strength decreases as a result of the increase in the amount of perlite used during the synthesis of geopolymers containing fly ash or GGBF [23].…”

Introduction of a mineral powder as a type of natural cementitious material in concrete: An experimental program

“…Test results indicate that the usage of waste marble improves concrete permeation properties . The mechanical properties of concrete improve by the use of perlite‐based geopolymer, or binary and ternary mixes of fly ash and silica fume, or scoria aggregates . The usage of metakaolin and diatomite in concrete with water reducing agent, to adjust workability instead of water, promotes an improvement in both the microstructure and the hardened state features such as porosity and mechanical strength .…”