Preliminary study of the effect of carbonation curing on geopolymers

Abstract

Carbonation curing differs from weathering carbonation since it is performed intentionally at the early ages of cement hydration. This cure involves applying different levels of CO2 (5% to 99%) to concrete for a short period of time, usually followed by conventional hydration. The objective of this article was to evaluate the carbonation curing in metakaolin-based geopolymer concretes, activated with NaOH and Na2SiO3, and compare them with Portland cement (PC) concrete. The following tests were applied: determination of pH, carbonation depth, water absorption by immersion, void index, and compressive strength. The results showed that after the carbonation curing, the geopolymer concrete had compressive strength and carbonation depth equivalent to the concrete with PC, but with a lower absorbed CO2 content. Although this type of cement absorbs less CO2 but is more sensitive to carbonation. The effect on the void ratio was not remarkable. Furthermore, the alkalinity of concretes can be partially recovered after subsequent curing by water immersion.

Carbonation Curing and Kinetics of Wood-Sodium Silicate Composites

“…In the presence of CO 2 , SS reacts to form silica gel with the subsequent removal of water to form a hardened glass material and a byproduct of sodium carbonate (Na 2 CO 3 ) and silica (SiO 2 ) as seen in chemical eq and stoichiometric eq . The dissolution behavior of Na 2 CO 3 contributes to the carbonation curing of the SS in the composite and facilitates bond formation. , When wood is added and treated with SS, CO 2 enhances the functional groups responsible for adhesion between the fibers and the matrix which can contribute to the existing properties and advantages of high strength, fire resistance, and durability as observed in a previous study normalN normala 2 normalO normalS normali normalO 2 ( aq ) + normalC normalO 2 → normalS normali normalO 2 ( aq ) + Na 2 CO 3 normalN normala 2 normalO · n normalS normali normalO 2 + 2 n normalH 2 normalO + normalC normalO 2 → normalN normala 2 normalC normalO 3 + n normalS normali false( normalO normalH false) 4 …”