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

据估计，萨斯喀彻温省每年有60万吨亚麻秸秆和2000吨聚丙烯打包机纱线被丢弃。以前的研究已经证明，从这些废物中提取的纤维可以在某些应用中有效地加固混凝土。然而，废纤维混凝土的性能必须得到更充分的表征，在推荐广泛使用之前，必须更好地了解其长期耐久性。通常将钢、塑料或玻璃的短纤维添加到混凝土中，以减少混凝土放置后立即产生的裂缝，并增加混凝土断裂所需的能量(这种特性被称为“韧性”)。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能有效地减少混凝土中裂缝的形成，但它们并不能显著增加韧性，而且还发现它们嵌入混凝土中会随着时间的推移而退化。拟议的研究将寻求更好地了解亚麻纤维降解的严重程度，并确定可以应用于纤维的处理方法，以提高纤维的耐久性和提高混凝土韧性的能力。最近，新的短切聚丙烯打包机绞线已被证明可以显著提高混凝土的韧性。拟议的研究将调查回收打包机绞线的性能，还将进行其他实验，以衡量不同类型的回收打包机绞线减少混凝土裂缝的能力。此外，拟议的研究计划有可能为目前的废物材料确定新的市场，并为混凝土行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线制成的纤维混凝土的开发，这些纤维混凝土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.