Abstract

Fiber reinforced mineral matrix composites have been used increasingly, through the last few decades, to build lightweight and thin structures, and to repair or strengthen old and damaged buildings. However, the reinforcing efficiency of these composites is limited by the low penetrability of cement particles into the space between the inner filaments, leading to a decrease in the composite’s mechanical performance due to the low yarn-matrix bond. To improve this bond, multifilament yarns are usually subjected to wet-process pre-impregnation using mineral or organic powders. However, this method is long, poorly controlled, and can be used only in the prefabrication field. The objective of this work is to compare this conventional pre-impregnation method with an alternative method called dry-process pre-impregnation which allows the production of large-size building elements in site. It is based on an alternating electrostatic field used to impregnate yarns with powder. Classical tensile tests were used to characterize glass yarn/ettringitic matrix composites, and completed by microstructure observations. Three configurations were tested: a dry yarn (D), a yarn pre-impregnated using the wet process (PIW) with ettringitic matrix particles, and a yarn pre-impregnated using the dry process (PID) with three different types of powders. Two composite reinforcement rates are investigated and their effect on the result is discussed. Mechanical and microscopic characterizations shed light on the effect of the pre-impregnation processes. It was found that the tensile behavior of the composite depends on the pre-impregnation method, pre-impregnation powder and reinforcement rate.

摘要

在过去的几十年里，纤维增强矿物基复合材料越来越多地用于建造轻质和薄型结构，以及修复或加固旧的和受损的建筑物。然而，这些复合材料的增强效率受到水泥颗粒对内部细丝之间空间的低渗透性的限制，导致复合材料的机械性能因纱线-基体结合度低而降低。为了改善这种粘合，复丝纱通常使用矿物或有机粉末进行湿法预浸渍。但这种方法时间长，控制不好，只能用于预制领域。这项工作的目的是将这种传统的预浸渍方法与一种称为干法预浸渍的替代方法进行比较，这种方法允许在现场生产大尺寸的建筑构件。它基于用于用粉末浸渍纱线的交变静电场。经典的拉伸试验用于表征玻璃纱/钙矾石基复合材料，并通过微观结构观察完成。测试了三种配置：干纱线 (D)、使用湿法工艺 (PIW) 预浸渍钙矾石基质颗粒的纱线，以及使用干法工艺 (PID) 预浸渍三种不同类型粉末的纱线。研究了两种复合材料的增强率，并讨论了它们对结果的影响。机械和微观表征揭示了预浸渍过程的影响。结果表明，复合材料的拉伸行为取决于预浸渍方法、预浸渍粉末和增强率。