Mechanics and durability of concrete reinforced with flax fibres or recycled baler twine

据估计，萨斯喀彻温省每年丢弃60万吨亚麻秸秆和2000吨聚丙烯打包机线。先前的研究表明，从这些废料中提取的纤维可以在某些应用中有效地增强混凝土。然而，必须更充分地表征废弃纤维增强混凝土的特性，并且在推荐广泛使用之前必须更好地了解其长期耐久性。通常在混凝土中加入钢、塑料或玻璃的短纤维，以减少混凝土浇筑后裂缝的形成，并增加混凝土断裂所需的能量（一种被称为“韧性”的特性）。这些特性对于混凝土路面、桥面、机场跑道和停车场地板的耐久性非常重要。虽然亚麻纤维已被证明可以有效地减少混凝土中的裂缝形成，但它们并不能显着增加韧性，而且当它们嵌入混凝土中时，它们也被发现会随着时间的推移而降解。拟议的研究将寻求更好地了解亚麻纤维降解的严重程度，并确定可能适用于纤维的处理方法，以提高纤维的耐久性和增加混凝土韧性的能力。新型剪短聚丙烯打包机线可显著提高混凝土的韧性。提出的研究将调查再生打包机线的性能。还将进行试验，以测量不同类型的再生打包机线减少混凝土开裂的能力。拟议的研究项目有潜力为现在的废料找到新的市场，并为混凝土工业提供低成本的替代纤维。预计这项研究将导致使用亚麻纤维或打包机线制成的纤维增强混凝土的发展，这些纤维或打包机线具有足以证明其在某些工程应用中的使用的特性。

An estimated 0.6 million tonnes of flax straw and 2000 tonnes of polypropylene baler twine are discarded in Saskatchewan every year. Previous research has demonstrated that fibres derived from these waste materials can be used to effectively reinforce concrete in some applications. However, the properties of the waste fibre-reinforced concretes must be more fully characterized, and their long-term durability must be better understood before they can be recommended for widespread use.    Short fibres of steel, plastics, or glass are commonly added to concrete to reduce the formation of cracks just after the concrete has been placed and to increase the amount of energy required to fracture the concrete (a property known as "toughness"). These properties are important for the durability of concrete pavements, bridge decks, airport runways, and parking garage floors. While flax fibres have been shown to be effective at reducing crack formation in concrete, they do not increase the toughness significantly and they have also been found to degrade over time when embedded in concrete. The proposed research will seek to better understand how severely flax fibres degrade and identify treatments that may be applied to the fibres to improve both the durability of the fibres and their ability to increase the toughness of concrete.    New chopped polypropylene baler twine has been shown to significantly increase the toughness of concrete. The proposed research will investigate the performance of recycled baler twine.  Experiments will also be conducted to measure the ability of different types of recycled baler twine to reduce cracking in concrete.    The proposed research program has the potential for identifying new markets for what are now waste materials and providing low-cost alternative fibres for use in the concrete industry.  It is expected that the research will lead to the development of fibre-reinforced concrete made using flax fibres or baler twine which possess properties that are sufficient to justify their use in certain engineering applications.