Reaction and alteration of mudstone with Ordinary Portland Cement and Low Alkali Cement pore fluids

普通ポルトランドセメント及び低アルカリセメントの間隙水と泥岩との反応と変質挙動

Bateman, K.; 天野 由記   ; 久保田 満*; 大内 祐司*; 舘 幸男  

Bateman, K.; Amano, Yuki; Kubota, Mitsuru*; Ouchi, Yuji*; Tachi, Yukio

The alkaline fluid arising from the cement-based materials will react with host rock to form a chemically disturbed zone around the geological disposal repository. To understand how these conditions may evolve, a series of batch and flow experiments were conducted with Horonobe mudstone and fluids representative of the alkaline leachates expected from both Ordinary Portland Cement (OPC) and Low Alkali Cement (LAC) leachates. The impact of the LAC was more limited, compared to the OPC leachates. Ion exchange reactions had an impact initially but thereafter the reaction was dominated by primary mineral dissolution, and in the case of OPC leachates precipitation of secondary C-S-H phases. The flow experiments revealed that precipitation of the secondary phases was restricted to close to the initial contact zone of the fluids and mudstone. The experimental results demonstrate that a combination of both batch and flow-through experiments can provide the insights required for the understanding of the key geochemical interactions and the impact of transport, allowing the spatial as well as temporal evolution of the alkaline leachate / mudstone system to be determined.