Dynamic Characteristics and Chloride Resistance of Basalt and Polypropylene Fibers Reinforced Recycled Aggregate Concrete
ADVANCES IN POLYMER TECHNOLOGY
Authors: Lu, Dong; Cao, Hui; Shen, Qiangru; Gong, Yue; Zhao, Cheng; Yan, Xiaohui
Abstract
Fiber polymer has been extensively used to improve the mechanical properties and durability of concrete. However, the studies of the effect of fiber polymer on the dynamic performance of recycled aggregate concrete (RAC) is still very limited. In this study, we prepared two types of RAC formulations: RAC reinforced with basalt fibers (BFs) and RAC reinforced with polypropylene fibers (PPs), and compared the effects of fiber types and contents on the air void content, workability (slump), mechanical properties (compressive and flexural strength), dynamic characteristics (dynamic modulus of elasticity and damping ratio), and chloride resistance of RAC. The experimental results showed that the air void content and slump value decreased with the increase of replacement percentage of RCA and fiber contents. Adding PPs provided a more negative effect on the slump of RAC than BFs. The mixtures containing 0.2% PPs and BFs both obtained the highest flexural strength. The addition of PPs was more effective than BFs in improving the damping ratio of RAC, and the mixtures containing 0.3% PPs and BFs both obtained the highest damping ratio. Compared to the RAC without addition of fiber, the charge passed of specimen with addition of PPs approximately increased by 45%, while the specimen with addition of BFs approximately increased by 30%, when the fiber content was 0.3%. This study demonstrates the potential of using fiber to promote the dynamic properties of RAC.
Use of the PAP/RAC model and GIS for zoning the risk of water erosion. Example o f the Tessa watershed (Tunisia)
REVUE INTERNATIONALE DE GEOMATIQUE
Authors: Zouaoui, Nassira; Mansour, Radhia; El Ghali, Abdessalem
Abstract
In the humid Mediterranean regions, particularly the NW of Tunisia, the Tessa catchment area is characterized by torrential and irregular rains, combined with significant deforestation, which causes severe erosion that carries away and redistributes the soil. The process of water erosion is very frequent and changes its dynamic aspect according to the evolution and spatial variation of the lithological nature of rocks, the geomorphology of landscapes, the geometry of watersheds and their bioclimatic situation. In this study, an appropriate methodological flowchart was followed by applying the PAP/RAC erosion mapping method, which is based on the principle of weighting the main factors that control erosive functioning: vegetation cover, slope and lithology. The interaction of the resulting maps and their spatial and temporal evolution at the scale of the Tessa watershed made it possible to establish a cartographic zoning by classifying the study area into several sectors according to their degrees of susceptibility arranged in 5 levels with percentages of 27.74% for the year 1985, 27.55% for 2003 and 27.81% for 2017 for the high and very high classes of the total area of the study area.