Fired-Siltstone Based Geopolymers for CO2 Sequestration Wells : A Study on the Effect of Curing Temperature

Wellbore integrity during Carbon Dioxide (CO2) storage in deep aquifers is a major problem as the currently used well cement will lose its integrity at higher temperatures and eventually leads to CO2 leakage into the atmosphere. Researchers have conducted several studies in order to find a proper well cement material and have tested several types of geopolymers mixing fly ash and different type of cements with an alkaline solution curing in different temperatures. This paper presents a study on geopolymer composites made from fired siltstone, slag as well as alkaline liquid which were cured at temperatures ranging from 23°C to 80°C. Five different types of geopolymer were prepared with ratios of fired siltstone (to 700 oC) and slag as 0:100, 20:80, 30:70, 40:60 and 50:50, separately. After preparing samples with various proportions under different temperatures, the mechanical properties of them were compared. The experimental results reveal that optimum curing temperature range is 50 to 70°C and addition of higher proportion of slag would help geopolymer gain better performance on mechanical strength compared to other geopolymer materials.