Potential applications for geopolymers in carbon capture and storage

Review on Geopolymers as Wellbore Sealants: State of the Art Optimization for CO2 Exposure and Perspectives

“…This is produced by the calcination of kaolinite, a clay mineral, at temperatures between 500 and 800 °C . Compared to GPs based on uncalcined kaolinite, metakaolin-based systems benefit from higher precursor reactivity (due to its amorphicity), leading to faster rates of dissolution/gelation and higher compressive strengths. ,, Compared to other GP precursors, metakaolin-based GPs also take advantage of the simplest alkali activation process required for GP synthesis, and their three-point flexural strengths are close to those of OPC (5–6 MPa). , However, in general, metakaolin-based GPs show lower durability, mainly caused by the plate-like shape (and thus higher surface area) of metakaolin particles, the resulting higher water demand, and, consequently, higher risks of drying shrinkage and cracking (Figure ). ,, Furthermore, the plate-like shape of metakaolin particles results in delayed setting and strength development, which can in turn lead to the evaporation of the hardener phase prior to the occurrence of full polycondensation.…”

“…However, the use of alkali carbonates and alkali aluminates has also been reported . The major roles of alkali reactants are (a) to provide high pH conditions required for the activation of the raw aluminosilicate precursors and (b) to provide alkali cations that can balance the negative charges induced when AlO 4 tetrahedra are incorporated into the cross-linked 3D network structure of the GPs. ,,,,, …”

“…Although the modern development of AAMs goes back to 1959, the study of GPs as green alternatives to OPC started coming into focus approximately 40 years ago. − Since then, the notable features of GPs have attracted the attention of academic and industrial sectors, resulting in increasing research intensity as well as progressively extensive application of GPs, such as in concrete, coating applications, refractory materials, insulation, and fire-resistant materials. , GPs have also been recognized as suitable candidates for zonal isolation of CCS wellbores mainly because of their lower permeability and lower Ca content compared to OPC-based sealants. ,− However, serious challenges to the use of GPs in zonal isolation of CCS wells do exist and need to be dealt with. Key issues noted in the literature include the sensitivity of GP activation and polymerization to water content, the viscosity profile, controlling thickening time, efflorescence (alkali leaching) and/or carbonation, and the low tensile strength of GPs. − Moreover, due to the system complexity caused by the wide range of parameters involved in GP synthesis, development of standard mix designs is still in its primary stage (laboratory scale). The need for liquid alkali-based activators with high pH imposes further challenges due to safety issues, and studies working on reducing the need for such activators are broadly welcomed. , Finally, while GPs have been recognized as potential wellbore sealant materials, and despite the extensive research conducted on the development of GP systems and a noticeable number of reviews published on various aspects of these materials, ,,,− the zonal isolation potential of GP systems in CCS operations has not been addressed as thoroughly.…”

Performance of lightweight cement pastes under CO2 storage conditions

“…In the past decades, since the industrial revolution, the greenhouse gas (GHG) concentration in the atmosphere has notably increased because of human activities [1]. Among all the emitted GHG, the most abundant one is CO2, which presents its highest concentration in the atmosphere in thousands of years [2]. The average global warming is about 1.0ºC since the pre-industrial era.…”

“…Given the high amount of energy production and other human activities, it is highly likely that by 2050 this value will reach 1.5ºC [3]. Therefore, some short and midterm solutions should be applied to improve the current situation, for which carbon capture and storage (CCS) arises as one of the main possible solutions since it could reduce GHG emissions by almost 90% [2], [4].…”