Multi-scale investigation of the performance of limestone in concrete
Multi-scale investigation of the performance of limestone in concrete
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DOI：
10.1016/j.conbuildmat.2014.10.042
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发表时间：
2015-01-30
影响因子：
7.4
通讯作者：
Weiss, W. Jason
中科院分区：
文献类型：
--
作者：
Bentz, Dale P.;Ardani, Ahmad;Weiss, W. Jason
石灰石（碳酸钙，CaCO 3）长期以来一直是混凝土的关键组分，无论是作为水泥生产的主要原料，添加到粘合剂组分中的细粉，还是细骨料和/或粗骨料的来源。本文着重于后两个例子，提供了一个多尺度的研究细石灰石粉和常规石灰石骨料对混凝土性能的影响。方解石形式的细石灰石粉末为早期硅酸钙水合物凝胶的成核和生长提供了有利的表面，加速和放大了硅酸盐水合作用，并且是碳酸根离子的来源，以参与与水泥（和粉煤灰）中存在的铝酸盐相的反应。相反，碳酸钙的文石多晶型物表现出不同的晶体（和表面）结构，因此在相似的粒度/表面积下既不加速也不放大硅酸盐水合。然而，由于这两种形式的碳酸钙在水中具有相似的溶解度，文石有助于增强所研究的系统中的铝酸盐相的反应性，主要是通过形成碳铝酸盐。在100%普通波特兰水泥（OPC）混凝土中，10体积%的OPC可以用等体积的石灰石粉末代替，同时保持可接受的性能。石灰石和硅质骨料之间的比较表明，前者往往提供更高的测量抗压强度在同等水平的水化，即使当两种骨料类型表现出类似的弹性模量。这表明，石灰石基混凝土中的界面过渡区表现出更高程度的结合，可能是由于石灰石表面的有利的物理（纹理）和化学性质。这些观察结果加强了利用石灰石的价值，以提高性能和21世纪世纪混凝土建筑的可持续性。爱思唯尔有限公司出版
Limestone (calcium carbonate, CaCO3) has long been a critical component of concrete, whether as the primary raw material for cement production, a fine powder added to the binder component, or a source of fine and/or coarse aggregate. This paper focuses on the latter two of these examples, providing a multi-scale investigation of the influences of both fine limestone powder and conventional limestone aggregates on concrete performance. Fine limestone powder in the form of calcite provides a favorable surface for the nucleation and growth of calcium silicate hydrate gel at early ages, accelerating and amplifying silicate hydration, and a source of carbonate ions to participate in reactions with the aluminate phases present in the cement (and fly ash). Conversely, the aragonite polymorph of CaCO3 exhibits a different crystal (and surface) structure and therefore neither accelerates nor amplifies silicate hydration at a similar particle size/surface area. However, because these two forms of CaCO3 have similar solubilities in water, the aragonite does contribute to an enhancement in the reactivity of the aluminate phases in the investigated systems, chiefly via carboaluminate formation. In 100% ordinary Portland cement (OPC) concretes, 10% of the OPC by volume can be replaced with an equivalent volume of limestone powder, while maintaining acceptable performance. A comparison between limestone and siliceous aggregates indicates that the former often provide higher measured compressive strengths at equivalent levels of hydration, even when the two aggregate types exhibit similar elastic moduli. This suggests that the interfacial transition zone in the limestone-based concretes exhibits a higher degree of bonding, likely due to the favorable physical (texture) and chemical nature of the limestone surfaces. These observations reinforce the value of utilizing limestone to increase the performance and sustainability of 21st century concrete construction. Published by Elsevier Ltd.