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

本研究建议是基于DFG项目的第一部分的结果，该项目题为在高压或超临界状态下用CO2对胶凝材料进行碳酸化。在研究工作中出现了新的问题，这些问题将通过进一步的研究来澄清，这些研究旨在利用碳酸化的积极影响来生产具有规定性质的创新胶凝材料，这些材料在处理后立即可用。在第一阶段的资金，参数，如碱含量，初始孔隙率（w/c比）和水分含量的硬化水泥浆试样，以及二氧化碳处理的压力和持续时间。此外，还研究了磨细粒化高炉矿渣、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。拟议的研究涉及的阶段，强度和体积的演变过程中和超临界或气态CO2处理后的开放性问题。和高压下的气态CO2。研究的重点是波特兰水泥的细度和矿物组成（C3 A和C4 AF含量，Na 2 O当量）的影响。对系统[CO2（超临界或气态）-孔隙溶液-硬化水泥浆相]的热力学计算将进一步理解不同条件下的碳化机理。未来一个可能的实际应用是处理多孔水泥基预制构件，如水泥防火板或墙板。特别是，接触区之间的玻璃纤维增强和硬化的水泥浆基质进行调查，以确定碳化的粘结行为和玻璃纤维增强的有效性的影响。

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.