Carbonation of cementitious building materials with CO2 at elevated pressure or in the supercritical state

这项研究建议是基于DFG项目的第一部分的结果，该项目名为在高压或超临界状态下用二氧化碳碳化胶凝材料。在研究工作中出现了新的问题，这些问题将通过进一步的调查得到澄清，目的是利用碳化的积极影响生产具有特定性能的创新胶凝材料，这些材料在处理后立即可用。在第一阶段的资助中，硬化水泥浆体试件的碱含量、初始孔隙率(W/C比)和含水率等参数以及CO2处理的压力和持续时间都有所不同。此外，还研究了磨细高炉渣、石灰石和白云石粉等添加剂对碳化过程和碳化材料性能的影响。这项拟议的研究涉及在超临界或气态二氧化碳处理过程中和处理后的物相、强度和体积的演变的开放问题。以及高压下的气态二氧化碳。研究重点是硅酸盐水泥的细度和矿物组成(C3A和C4AF含量，Na2O当量)的影响。[CO2(超临界或气态)-气孔溶液-水泥浆体相]体系的热力学计算将进一步加深对不同条件下碳化机理的理解。未来一个可能的实际应用是处理多孔性水泥基预制构件，如水泥防火墙板或墙板。特别是，为了确定碳化作用对玻璃纤维增强材料的粘结性能和有效性的影响，需要研究玻璃纤维增强材料和硬化水泥浆体基质之间的接触区。

This research proposal is based on the results of first part of the DFG project entitled carbonation of cementitious materials with CO2 at elevated pressures or in the supercritical state. New issues have emerged in the research work which are to be clarified by further investigations aimed at the utilisation of the positive effects of carbonation for the production of innovative cementitious materials with defined properties which are immediately available after treatment. In the first period of funding, parameters such as alkali content, initial porosity (w/c ratio) and moisture content of the hardened cement paste specimens were varied as well as the pressure of the CO2 treatment and its duration. Moreover, the effect of additions such as ground granulated blast-furnace slag, limestone and dolomite flour on the carbonation process and the properties of the carbonated material was investigated. The proposed research deals with open questions on the evolution of phases, strength and volume during and after treatment with supercritical or gaseous CO2. and gaseous CO2 at elevated pressures. The investigations focus on the effect of the fineness and mineralogical composition of Portland cement (C3A, and C4AF content, Na2O eq.). Thermodynamic calculations for the system [CO2 (supercritical or gaseous) - pore solution -hardened cement paste phases] will further the understanding of the mechanisms of carbonation under different conditions.One possible practical application in the future is the treatment of porous cement-based prefabricated elements such as cementitious fire protection panels or wall boards. In particular, the contact zone between a fibreglass reinforcement and the hardened cement paste matrix is to be investigated in order to determine the effect of carbonation on bonding behaviour and the effectiveness of fibreglass reinforcement.