Multi-functional aggregates for enhanced concrete performance and its application

混凝土材料作为一种建筑材料，由于其多功能性和成本效益，在发达国家无处不在，但其增加功能的巨大潜力仍未得到充分开发。“多功能”混凝土的前景并不新鲜；报告的研究实例包括光催化和导电混凝土以及具有增强热学和声学性能的混凝土。多功能主题的重要性已经推动了一些重要的商业利益，一些项目甚至已经发展到规模示范和商业结构。混凝土由粘合剂（水泥）、骨料（不同大小的石头）和水组成。可能会有额外的添加剂来提供设置控制。将功能材料掺入混凝土的传统方法通常侧重于对粘合剂相（水泥粉）进行改性或添加。活性添加剂的分散性差或被水泥水化产物遮挡会严重影响其性能。本文提出的新方法是在聚合体上分散活性添加剂（光催化剂或导电材料）。初步实验表明，与传统的功能化方法相比，该方法在性能上有了重要的改进。这在很大程度上可归因于活性添加剂分散在湿混凝土搅拌之前的稳定性。在搅拌和浇筑过程中，骨料的空间分布得以保留，在某些情况下，骨料的孔隙率控制有望限制水泥的封堵程度。对于导电材料，整个基体的接触连续性是很重要的。通过将导电骨料与常规混合的导电材料结合在粘结剂中，可以获得更连续、因此更导电的基体。该项目汇集了中英两国在光催化和材料化学方面具有互补专业知识的团队，并专注于光催化和导电混凝土。每一种都有潜在的高社会和经济影响的应用。一种可以通过电来感知自身结构缺陷或无需使用除冰盐即可自行除冰的混凝土将具有明显的优势和环境效益，其改进的电磁屏蔽特性对加强信息安全可能很重要。英国和中国都有高人口密度和空气污染的中心。中国也在迅速发展其已建成的基础设施，提供了与受污染的大气密切接触的大量且不断增长的混凝土表面积，并为光催化剂的支持提供了极好的机会。这在清除环境污染物方面是有效的，特别是在已知车辆交通排放（含挥发性有机碳和氮氧化物）对人口健康有不利影响的城市地区。

Concrete materials are ubiquitous in the developed world due to their versatility and cost-effectiveness as a construction material, but their great potential for increased functionality remains underdeveloped. The prospect of 'multifunctional' concrete is not new; examples of reported research include photocatalytic and electrically conductive concretes and concretes with enhanced thermal and acoustic properties. The importance of the multifunctionality theme has driven some significant commercial interests, and some projects have even developed through to scaled demonstrations and commercial structures. Concretes comprise a binder (the cement), aggregate (stone in different size fractions) and water. There may be additional additives to provide setting control. Conventional approaches to the incorporation of functional materials to concrete have typically focused on modification of or addition to the binder phase (the cement powder). Performance can be strongly influenced by poor dispersibility or occlusion of the active additive by cement hydration products. The novel approach addressed here is in the dispersion of the active additive (photocatalyst or electrically conducting material) on the aggregate.Preliminary experiments have shown important improvements in performance when compared with conventional functionalizing approaches. Much of this can be attributed to the stabilization of active additive dispersion prior to mixing in the wet concrete. Spatial distribution on the aggregate is preserved during mixing and casting and, in some cases, porosity control of the aggregate can be expected to limit the degree of cement occlusion. For electrically conducting materials, continuity of contact throughout the matrix is important. By combining conductive aggregate with conventionally mixed conductive materials in the binder fraction, a more continuous, and therefore more conductive matrix can be expected.The project brings together groups from the UK and China with complementary expertise in photocatalysis and materials chemistry and focuses on photocatalytic and electrically conductive concretes. Each has applications with potentially high social and economic impacts. A concrete that electrically senses itself for structural defects or can de-ice itself without the use of de-icing salts would have obvious advantages and environmental benefits, and its improved electromagnetic shielding characteristics could be important in enhancing information security. Both the UK and China has centres of high population density and air pollution. China is also rapidly developing its built infrastructure, offering a significant and growing concrete surface area in intimate contact with the polluted atmosphere and an excellent opportunity for the support of photocatalysts. These are effective in the removal of environmental pollutants, particularly in urban areas where vehicular traffic emissions (containing volatile organic carbons (VOCs) and oxides of nitrogen (NOx)) are known to have adverse effects on the health of the population.