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

用于结构应用的由花岗岩碎骨料和惰性填料组成的环保混合物的优化

• 批准号: 530552-2018
• 负责人: MorettiSanchez, LeandroFrancisco
• 金额: $ 1.6万
• 依托单位: University of Ottawa
• 依托单位国家: 加拿大
• 项目类别: Collaborative Research and Development Grants
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=697971
• 关键词: Optimization; eco; friendly; mixtures; composed

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.

民用建筑行业的压力越来越大，要求采用更环保的可持续方法来减少二氧化碳排放。作为世界上最常用的建筑材料，混凝土对环境的影响尤为显著，而且还在继续快速增长。1990年至2002年，全球对混凝土的需求增加了400%，预计未来40年全球水泥产量将增加2.5倍。波特兰水泥通常占混凝土内含能量的三分之二以上，其生产产生全球温室气体排放的5%。一种在不牺牲性能的情况下减少混合物中波特兰水泥含量的新策略是使用颗粒填充模型和惰性填料材料，其具有比波特兰水泥更低或相似的粒度分布。通过减少水泥浆填充的体积，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索引（即，产生1 MPa的性能（例如抗压强度）所需的粘合剂的量已被用于量化混凝土混合物的环境友好程度，对于标准常规混合物，典型值为10至15 [kg/m3.MPa]。混凝土的内含能量还与骨料和构成混凝土混合物的其他原材料的提取和运输直接相关。此外，使用河砂作为细骨料的来源导致自然资源枯竭，地下水位下降，并带来其他农业挑战。为了解决这一问题，已提出用碎石废物替代河砂，这种废物的颗粒大小分布与沙子（即机制砂）相似，甚至介于沙子和波特兰水泥之间。研究表明，在建筑工地附近的优质骨料来源可以最大限度地降低运输成本和能源使用，而破碎过程中产生的细渣（即机制砂和惰性填料）可以部分替代波特兰水泥。因此，使用来自当地采石场的粗/细骨料（粒度>100 µm）和惰性填料（粒度<100 µm）可以成为生产生态高效混凝土材料的新策略，同时显著减少环境足迹。此外，还缺乏一致和科学的混合设计程序，特别是解决颗粒堆积模型技术，占替代细残留物的生态友好型混凝土。拟议的研究项目将集中于开发一种新的混合设计程序，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物，并评估花岗岩基采石场加工材料和副产品的使用，特别是破碎骨料和惰性填料，以生产具有有趣的短期和长期性能的环保低水泥混凝土。该CRD的科学效益包括开发一种新的基于性能的设计方法，用于使用当地可用的材料配比环保混合物，这可以显着减少加拿大各地混凝土供应商和承包商的整体环境影响。这一结果预计将为Fowler的细花岗岩骨料生产创造新的收入来源，目前还没有用于混凝土应用，以及使用采石场副产品的新机会。