Caractérisation et modélisation des déformations résiduelles dans les tubes en polyéthylène haute densité de transport de gaz

Dans cette communication, nous présentons une approche expérimentale portant sur l’étude de l’évolution des déformations résiduelles à travers la paroi des tubes en polyéthylène HDPE-80 sur le comportement mécanique d'une part et d'autre part, sur l’effet des agents chimiques se trouvant dans le sol et qui peuvent entre en interaction avec les tubes enfouis. Les résultats indiquent que le polyéthylène est très influencé par la présence d’acides et de solvants qui le dégradent. La modélisation des contraintes et des déformations résiduelles obéit à des équations très différentes de celles qui régissent la mise en forme du fondu. On remarque que les courbes des différentes éprouvettes ont la même allure, et les déformations commencent juste après le sectionnement donc à l'instant t = t0. Ces courbes ont une allure semblable à celle obtenue pour les courbes typiques de fluage des matériaux viscoélastiques semi-cristallins rencontrés dans la littérature

Pathology Evaluation and Repair of Bridges in Masonry

The field of repair and rehabilitation of civil engineering works is evolving. Indeed, most of these structures, especially masonry structures, are over 50 years old and many of them require maintenance and repair work due to their deteriorated condition. To achieve this objective, a study was carried out concerning the different pathologies affecting the masonry bridges, but also the ways and means necessary for the evaluation and repair of the affected works. The results of this work have not only helped to carry out the diagnosis and verification of the structural state of the bridge over river Kentra Stora Skikda (North-East of Algeria), on the section of the 3AA National Road Skikda, but also for the proposal of repair solutions best adapted to the disorders observed

Optimizing polymer-stabilized raw earth composite with plant fibers reinforcement for historic building rehabilitation

This research focuses on the optimization of formulation, characterization, and damage analysis of plant fiber-reinforced polyester resin composites (jute and date palm). To better understand the characteristics and mechanical behavior of these materials, this study investigates the influence of resin content and plant fibers on the physico-mechanical behavior of the resin composites. Resinous composites consisting of polyester resin and raw earth were studied using a novel formulation based on an empirical method that follows the principle of earth saturation with polyester resin. Saturation was achieved with a 28% content of polyester resin, which appeared to be an optimal blend for the earth–resin composite. Plant fibers were randomly incorporated as reinforcement in the composites at various percentages (1%, 2%, and 3%) and lengths (0.5 cm, 1 cm, and 1.5 cm). Mechanical tests including bending, compression, and indentation were conducted to evaluate the mechanical properties of the composites. Analysis of fracture morphology revealed that the deformation and rupture mechanisms in bending, compression, and indentation of these composites differ from those of traditional concrete and cement mortar. The obtained results indicate that the composites exhibit acceptable performance and could be favorably employed in the rehabilitation of historic buildings

Use of Eco-Friendly Materials in the Stabilization of Expansive Soils

Volume change of expansive soils is a challenging issue, which affects various engineering structures all over the world. Consequently, we need environmentally-friendly and cost-effective soil stabilizers to address the challenges related to expansive soils. The utilization of natural fibers allows for the reduction in environmental impact since they are renewable and biodegradable raw materials. Moreover, the current article presents an experimental approach to study the effect of natural fibers on the mechanical behavior of expansive soils. Various experimental tests—such as Atterberg limits, standard compaction, direct shear, swelling potential, and swelling pressure—were conducted on control and treated soil samples using different percentages of fibers. The results of measurements of the physico-mechanical properties after reinforcement of the soil with 1%, 5%, and 10% of natural fibers indicate that the mechanical behavior of expansive soils is greatly influenced by the addition of natural fibers. To conclude, 86% reduction was observed in the swelling coefficient of treated soil. Future research can be done to check the durability of the current practice in detail

Use of Eco-Friendly Materials in the Stabilization of Expansive Soils

Volume change of expansive soils is a challenging issue, which affects various engineering structures all over the world. Consequently, we need environmentally-friendly and cost-effective soil stabilizers to address the challenges related to expansive soils. The utilization of natural fibers allows for the reduction in environmental impact since they are renewable and biodegradable raw materials. Moreover, the current article presents an experimental approach to study the effect of natural fibers on the mechanical behavior of expansive soils. Various experimental tests—such as Atterberg limits, standard compaction, direct shear, swelling potential, and swelling pressure—were conducted on control and treated soil samples using different percentages of fibers. The results of measurements of the physico-mechanical properties after reinforcement of the soil with 1%, 5%, and 10% of natural fibers indicate that the mechanical behavior of expansive soils is greatly influenced by the addition of natural fibers. To conclude, 86% reduction was observed in the swelling coefficient of treated soil. Future research can be done to check the durability of the current practice in detail

Tensile Force Distribution And Development Within Geogrid-Reinforced Retaining Wall

Geogrid-reinforced earth retaining walls used to improve soil quality, and provide additional shear strength in the soil mass through the tensile strength in the reinforcement layers. A numerical model was developed by finite element code PLAXIS2D, of a segmental facing geogrid-reinforced retaining wall. This research has been carried out to investigate the effect of loading increments, loading increments width, loading increments location, facing inclination angle, geogrid inclination angle, and geogrid-soil friction factor, on the behaviour of a geogrid-reinforced soil retaining wall. The results show that the failure plane occurred in the reinforced zone at the mid-height, this observation contradicted the triangular distribution with depth assumed in conception methodologies for reinforced soil retaining wall. The distribution of peak tensile strength with depth was bilinear at high loading increments and became trapezoidal at low loading ones. Furthermore, it was found that the behaviour of a geogrid-reinforced soil retaining wall is independent of loading increments width beyond 0.5H. It also seems that the loading increments location can change the shape and the position of the peak tensile strength. It also seems that the geogrid inclination angle has a major effect on the lateral facing displacements and safety factor

Recent advances in expansive soil stabilization using admixtures: current challenges and opportunities

Expansive soils are problematic for direct engineering applications in their natural state because of the shrink-swell phenomenon. Numerous stabilizers and methods have been used to stabilize expansive soils as an effort to make them more practical for construction purposes. Searching for suitable soil stabilizers to overcome difficulties caused by the expansive soils is the key issue, not only in terms of achieving the required soil geotechnical characteristics but also in terms of environmental and economic concerns. The purpose of this article was to assess the current trends, challenges, and opportunities of various admixtures utilized for expansive soil improvement, as well as their economic and environmental consequences. A critical review of various admixtures commonly used as soil stabilizers, including marble waste powder, fly ash, eggshell powders, stone waste, and lime powder is conducted. Furthermore, a the review was also focused to analyze the offered stabilizers in terms of soil geotechnical properties and sustainability in the field application