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Effect of magnesium-bearing additives on the properties of a granite-based geopolymer sealant for CCS
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 84th EAGE Annual Conference & Exhibition, Jun 2023, Volume 2023, p.1 - 5
Abstract
Among the major challenges in Carbon Capture and Storage (CCS) is maintaining the integrity of injection wellbores, as the degradation of Ordinary Portland Cement (OPC) in the presence of rich CO2-brine systems may result in leakage. Geopolymers (GPs) are promising alternatives for OPC that can be synthesized through the alkali activation of low Ca-content aluminosilicate precursors. Research has shown the notable impact of system chemistry (Si/Al, Si/(Na+K), Si/Ca, etc.) on the setting time, rheology, permeability, and mechanical durability of GP systems. However, merely a limited number of studies has investigated the role of Mg-content in determining the properties of GPs. This research aims to fill the gap through analyzing the impact of various Mg-bearing additives (Mg(NO3)2, MgSO4, and MgO) on a granite-based GP system, taking into account the consistency of the fresh mix, and uniaxial compressive strength (UCS) development. In addition, the morphology of the materials was examined through scanning electronic microscopy (SEM). Results showed that MgO caused acceleration of GP setting, while Mg(NO3)2 acted as a retarder and MgSO4 did not affect the setting behavior of the GP system. In addition, only Mg(NO3)2 had a non-negligible impact on mechanical strength, causing a 22.51 % reduction in UCS.