Engineered Concrete through Tailored Cementitious Materials by Tribochemistry, Surface Treatment and Activation

水泥是世界上使用最广泛的建筑材料，其产生的二氧化碳约占人类活动产生的总二氧化碳的5%。水泥/混凝土行业承诺通过减少混凝土中的水泥熟料数量来减少温室气体排放。其中一种方法是使用工业副产品(硅灰、矿渣、飞灰)中的辅助胶凝材料(SCM)和替代胶凝材料(ASCM：玻璃粉、偏高岭土、煅烧粘土)，它们可以部分或全部取代混凝土中的水泥。尽管掺SCM的混凝土可以产生与素混凝土相当或更高的性能，但其潜力尚未被充分挖掘。在任何情况下，都会出现早期强度低、凝结时间长、分散性差、反应速度慢、化学收缩和混凝土开裂的情况。这项研究计划专注于通过摩擦化学、表面化学活化、分散和堆积密度工具来优化SCM的性能，以设计耐用、可持续的混凝土结构。*类固体水泥和SCM的研磨会产生复杂的转变。机械能破坏材料的原子和分子结构，产生裂缝、微缺陷和新的表面。晶体结构中微缺陷中的能量可以修饰和复杂化固体颗粒的反应性和流变性。当不同的材料(熟料、SCM、ASCM)夹杂在一起时，这种效果会更加复杂。化学活化也可以用来增加SCM和ASCM的水化。在这个项目中，SCM将通过研磨和表面处理来定制，以设计具有高颗粒堆积密度的混凝土。研磨表面处理的混合物将用显微镜和光谱分析技术进行分析。将通过量热法、纳米压痕和电子显微镜测量来研究SCM对无水泥硅酸盐粘结剂的粘结剂水化和活化的摩擦化学效应。*了解材料研磨对颗粒表面(摩擦化学)和表面处理的影响，再加上优化的粘结剂堆积密度，将使您更好地掌握水化过程。这些协同效应将被调节，以量身定制具有最佳流变性、力学性能和耐久性的混凝土。*该模型的结果将在中试规模和现场试验混凝土上得到验证。*除了培训加拿大建筑业随时可用的HQP外，成果将是混凝土行业可以访问的主要数据库和模型，用于在加拿大建造耐用和可持续的基础设施。********

The production of cement—the world's most widely used construction material—causes about 5% of the total CO2 caused by human activity. The cement/concrete industries have committed to reduce their greenhouse emissions by reducing the amount of cement clinker in concrete. One such means is using supplementary cementitious materials (SCMs) from industrial by-products (silica fume, slag, fly ash) and alternative SCMs (ASCMs: glass powder, metakaolin, calcined clays) that can partially or totally replace cement in concrete. Although concretes with SCMs can yield equivalent or higher properties than plain concrete, their potential has yet to be fully be exploited. In any cases, low early strength, long setting time, poor dispersion, slow reactivity, chemical shrinkage, and concrete cracking are reported. This research program focuses on optimizing SCM properties with tribochemistry, surface chemical activation, dispersion, and packing-density tools to design durable, sustainable concrete structures. ***The grinding of solid-like cement and SCMs generates complex transformations. The mechanical energy disrupts the materials' atomic and molecular structures, producing cracks, micro-defects and new surfaces. The energy in the micro-defects of the crystalline structure can modify and complexify solid-particle reactivity and rheology. This effect is more complex when different materials (clinker, SCMs, ASCMs) are interground. Chemical activation can also be used to increase SCM and ASCM hydration. In this program, SCMs will be tailored through grinding and surface treatment to engineer concretes with high particle-packing densities. The milled surface-treated mixtures will be analyzed with microscopic and spectroscopic techniques. Tribochemical effects of SCMs will be investigated on binder hydration and activation of portland cement-free binders through calorimetry, nano-indentation, and electron-microscopic measurements. ***Understanding the effect of material grinding on particle surfaces (tribochemistry) and surface treatment coupled with an optimized packing density of the binder will provide better mastery over the hydration process. These synergetic effects will be modulated to tailor a concrete with optimized rheology, mechanical performances, and durability. ***Results obtained from this modeling will be validated on pilot-scale and in situ experimental concretes. ***In addition to train HQP readily available for the Canadian construction industry, the outcome will be a major database and model accessible to the concrete industry for building durable and sustainable infrastructures in Canada. ********