Innovative and sustainable shrinkage-compensating concretes

该项目是CRIB拉瓦尔（拉瓦尔大学）持续努力的一部分，旨在帮助建立混凝土维修作为一个合法的工程学科。最终，基本目标是为维修行业提供实施合理设计方法和维修规范所需的知识。在这方面，实现尺寸兼容性仍然是最重要的考虑因素之一，以便始终实现持久的维修工作，而不会发生有害的开裂。波特兰水泥混凝土的干燥收缩通常是不可避免的，尽管其幅度可以通过优化或修改组成参数来减小，但其仍然显著大于其极限拉伸应变。相反，通过使用矿物膨胀剂，收缩补偿混凝土（ShCC）的使用可以允许实现相对于干燥收缩的零维平衡。近年来在拉瓦尔大学进行的评估收缩补偿混凝土（ShCC）作为修补材料的潜力的实验工作，实际上已经取得了相当有前途的结果。然而，需要更多的研究，把ShCC系统变成一个真正可靠和多功能的维修选择。在尚未解决的问题中，维修收缩补偿过程背后的工程技术尚未开发。需要深入研究膨胀过程的类型及其对各种水泥/粘结剂系统的有效性的总体影响。预期的研究工作将为优化规范、构造和施工方法（修补厚度、粘结或锚固、材料选择、养护技术和持续时间等）提供依据。ShCC维修需要解决的另一个方面是缺乏合适的测试方法来表征ShCC，以指导规格和进行质量控制。将致力于调整或开发旨在更好地捕获ShCC的特定体积变化行为的测试程序。虽然研究计划将主要致力于开发更耐用和可持续的收缩补偿修复混凝土，但研究的目的是评估收缩补偿是否可以成功地用于其他专业混凝土。最终，研究结果预计将有利于整个混凝土建筑行业的可持续发展。

This project is part of a continuing effort at CRIB Laval (Laval University) intended to help establishing concrete repair as a legitimate engineering discipline. Ultimately, the fundamental objective is to provide the repair industry with the knowledge required to implement rational design methods and specifications for repairs. In that quest, the achievement of dimensional compatibility remains one of the most important considerations in order to consistently achieve lasting repair works that do not undergo harmful cracking. Drying shrinkage of Portland cement concrete is generally inevitable and, although its magnitude can be reduced by optimizing or modifying the composition parameters, it remains significantly larger than its ultimate tensile strain. Conversely, the use of shrinkage-compensating concrete (ShCC) may allow to achieve a zero-dimensional balance with respect to drying shrinkage, through the use of a mineral expansive agent. The experimental work carried out in recent years at Laval University to evaluate the potential of shrinkage-compensating concretes (ShCC) for use as repair materials has in fact yielded quite promising results. Nevertheless, more research is required to turn ShCC systems into a truly dependable and versatile repair option. Among the issues still unresolved, the engineering behind the shrinkage compensation process for repairs has yet to be developed. The overall influence of the type of expansive processes and their effectiveness with a variety of cement/binder systems needs to be investigated in depth. The anticipated research work will provide a basis for optimizing specifications, detailing and construction methods (repair thickness, bonding or anchoring, material selection, curing technique and duration, etc.) of ShCC repairs. Another aspect that needs to be addressed is the lack of suitable tests methods to characterize ShCC, to guide the specifications and to perform quality control. Efforts will be devoted to adapt or develop test procedures intended to better capture the particular volume change behavior of ShCC's. While the research program will be primarily dedicated to the development of more durable and sustainable shrinkage-compensating repair concretes, an objective of the research is to evaluate whether shrinkage compensation can be successfully exploited in some other specialty concretes. Ultimately, the findings are expected to benefit the overall concrete construction industry towards sustainability.