Optimization of eco-friendly mixtures composed by granite-based crushed aggregates and inert fillers for structural applications

民用建筑行业正面临越来越大的压力，要求采用更具环境可持续性的方法来减少二氧化碳排放。混凝土作为世界上最常用的建筑材料，对环境的影响尤其显著，而且还在以快速的速度增长。1990年至2002年间，全球对混凝土的需求增长了400%，预计未来40年全球水泥产量将增长2.5倍。波特兰水泥通常占混凝土所含能源的三分之二以上，其生产产生的温室气体排放量占全球温室气体排放量的5%。一种在不牺牲性能的情况下减少混合料中波特兰水泥含量的新策略是使用颗粒堆积模型和惰性填充材料，它们的颗粒尺寸分布低于或接近波特兰水泥。通过减少水泥浆体的填充量，在某些情况下，波特兰水泥含量可以显著减少50%以上。此外，使用bi指数(即产生1兆帕性能所需的粘结剂的量，例如抗压强度)来量化混凝土混合料对环境的友好程度，标准传统混合料的典型值介于10至15[千克/立方米]之间。混凝土的体现能量还与集料和构成混凝土混合料的其他原材料的提取和运输直接相关。此外，使用河沙作为细骨料的来源已导致自然资源枯竭，降低了地下水位，并带来了其他农业挑战。为了解决这一问题，已提议将碎石废料作为河砂的替代品，其粒度分布类似于沙(即人工砂)，甚至介于砂和波特兰水泥之间。已证明，建筑工地附近的优质集料来源可以最大限度地减少运输成本和能源消耗，而粉碎过程中产生的细小残留物(即人工砂和惰性填料)可用作波特兰水泥的部分替代品。因此，使用当地采石场的粗/细骨料(颗粒大小为100微米)和惰性填料(颗粒大小为100微米)可以作为一种新的策略来生产环保混凝土材料，同时显著减少环境足迹。此外，缺乏一致和科学的配合比设计程序，特别是解决颗粒堆积模型技术，说明生态友好型混凝土中的替代细小残留物。拟议的研究项目将集中于开发一种新的配合比设计程序，包括颗粒填充技术，以设计用于结构应用的低水泥混凝土混合料，并评估以花岗岩为基础的采石场加工材料和副产品，特别是碎石和惰性填料的使用，以生产具有有趣的短期和长期性能的环保低水泥混凝土。这种CRD的科学益处包括开发了一种新的基于性能的设计方法，使用当地可获得的材料来配制环保混合料，这可以显著减少加拿大各地混凝土供应商和承包商对整体环境的影响。这一结果预计将为Fowler生产目前未用于混凝土应用的细花岗岩基集料创造新的收入来源，并为使用采石场副产品提供新的机会。

Pressure is mounting in the civil construction industry to adopt more environmentally sustainable methods to reduce CO2 emissions. As the most commonly used construction material in the world, concrete has a particularly significant environmental impact, which continues to increase at a rapid rate. Global demand for concrete has increased by 400% between 1990 and 2002, and a 2.5-fold increase in global cement production is expected over the next 40 years. Portland cement often constitutes to more than two-thirds of the embodied energy of concrete, and its production generates 5% of global greenhouse gas emissions. A novel strategy to reduce Portland cement content in mixtures, without sacrificing performance, is the use of particle packing models and inert filler materials, which have lower or similar particle-size distribution than Portland cement. By reducing the volume to be filled by cement paste, Portland cement content can be significantly reduced by more than 50% in some cases. Moreover, the use of the bi index (i.e., the amount of binder required to produce 1 MPa of property, for example, compressive strength, has been used to quantify how environmentally friendly concrete mixtures may be, with typical values ranging from 10 to 15 [kg/m³.MPa] for standard conventional mixes. The embodied energy of concrete is also directly linked to extraction and transportation of aggregates and other raw materials that comprise concrete mixes. Furthermore, the use of river sand as a source of fine aggregates has led to the depletion of natural resources, lowering the water table, and posing other agricultural challenges. To address this concern, crushed stone waste, presenting particle-size distributions similar to sand (i.e. manufactured sand), or even lying between those of sand and Portland cement, has been proposed as an alternative to river sand. It has been shown that sources of good quality aggregates near construction sites can minimize transportation costs and energy use, while the fine residues generated during the crushing process (i.e. manufactured sand and inert fillers), may be used as a partial replacement for Portland cement. Hence, using coarse/fine aggregates (Particle Size>100 µm) and inert fillers (Particle Size<100 µm) from local quarries can be a novel strategy to produce eco-efficient concrete materials with a significantly reduced environmental footprint. Moreover, there is a lack of consistent and scientific mix-design procedures, especially addressing particle-packing model techniques, accounting for alternative fine residues in eco-friendly concrete. The proposed research project will focus on develop a new mix- design procedure including particle packing techniques to design low-cement concrete mixtures for structural applications, and evaluate the use of granite-based quarry processing materials and by-products, particularly crushed aggregates and inert fillers to produce eco-friendly low cement concrete with interesting short and long-term performance. The scientific benefit of this CRD include the development of a new performance-based design methodology for proportioning eco-friendly mixtures using locally available materials, which can significantly reduce the overall environmental impact of concrete suppliers and contractors across Canada. This result is expected to create new revenue streams for Fowler for fine granite-based aggregate production, which is not currently used for concrete applications, as well as a new opportunity for using quarry by-products.