Compressive stress-strain behaviour of cement mortar-composites reinforced with short sisal fibre
Compressive stress-strain behaviour of cement mortar-composites reinforced with short sisal fibre
复制标题
DOI：
10.1590/s1516-14392013005000181
复制
发表时间：
2013-11
影响因子：
1.7
通讯作者：
P. L. Lima;R. D. T. Filho;J. M. Filho
中科院分区：
文献类型：
--
作者：
P. L. Lima;R. D. T. Filho;J. M. Filho
为了设计使用剑麻纤维增强砂浆复合材料的建筑构件，需要复合材料在拉伸和压缩载荷下的应力-应变曲线。在这项研究中，开发了短剑麻纤维水泥基复合材料，并通过实验表征了它们在压缩下的应力-应变行为。该复合材料由两种砂浆基质组成，一种是自密实的，一种是正常稠度的，并用体积分数为 2% 至 6% 的随机分布的短剑麻纤维（长 25 毫米和 50 毫米）进行增强。根据实验结果，基于 Mazars (1986) 提出的损伤理论，提出了复合材料的压缩本构定律。该理论用于对应力-应变曲线的上升分支进行建模，并提出与纤维增强指数相关的损伤参数，以允许对复合材料的峰值后行为进行建模。然后使用文献中提供的结果验证修改后的模型。研究中获得的实验结果表明，在水泥基体中添加短剑麻纤维往往会降低其弹性模量、峰值应力和应变，并增加其韧性。然而，自密实基体的使用可以使剑麻纤维更好地分散，并获得具有优越性能的复合材料。修改后的分析模型能够高精度地预测剑麻纤维-砂浆复合材料应力-应变曲线的上升和下降分支，并可以评估纤维增强指数对材料损伤的影响。在上升分支中，纤维体积在 2% 到 6% 之间时，损伤从 40% 增加到 70%。另一方面，在下降分支中，纤维体积的变化使损伤从 65% 减少到 60%。
To design building elements using sisal fibre reinforced mortar composites, the stress-strain curves of the composites both under tensile and compression load is needed. In this study short sisal fibre-cement based composites were developed and their stress-strain behaviour under compression characterized experimentally. The composites consisted of two mortar matrices, one self-compacting and one of normal consistency, reinforced with randomly distributed short sisal fibre (25 and 50 mm long) in volume fractions ranging from 2% to 6%. Based on the experimental results a compressive constitutive law for the composites was proposed based on the damage theory developed by Mazars (1986). This theory was used to model the ascending branch of the stress-strain curve and a damage parameter associated to the fibre-reinforcing index is proposed to allow the modelling of the post-peak behaviour of the composites. The modified model was then validated using results available in the literature. The experimental results obtained in the study indicated that the addition of short sisal fibres to cement matrices tends to reduce its elastic modulus, peak stress and strain and to increase its toughness. However, the use of a self-compacting matrix allowed better sisal fiber dispersion and composites with superior performance were obtained. The modified analytical model was able to predict with good accuracy the ascending and descending branch of the stress-strain curves of the sisal fiber-mortar composites and allowed evaluating the effect of fibre reinforcing index on material damage. In the ascending branch, an increase in the damage from 40% to 70% is recorded for fiber volume ranging from 2 to 6%. In the descending branch, on the other hand, the variation of fiber volume allowed a reduction of the damage from 65% to 60%.