Stability Behavior of Lime Stabilized Gypseous Soil

In arid and semi-arid zones, gypsum (CaSO4.2H2O) is one of the soluble of the common minerals that found in soils. In Iraq, gypseous soils is a worldwide stability problem that causes extensive damage upon wetting, and occur in certain areas characterized by variation of climatic conditions. The results of the stability behavior of lime stabilized gypseous soil where present in this paper under different tests. These tests were erosion, leaching and soaking. Erosion test was conducted under different variables such as water temperature, water velocity and flow duration. The soil used in this study was taken from a site near Al – Hader district about (80 km) from Mosul city. Its main geotechnical index properties are liquid limit is (46%), plastic limit (22%) and specific gravity is 2.58. The amount of the gypsum was 20%. The soil samples were treated with optimum lime percent (4%) depending on the Illinois procedure. A gypseous soil with 20% gypsum content was used and stabilized with 4% lime. All stabilized soil samples were cured for 2 days at 490 C. The results indicate that, the loss in weight increased for samples subjected to the flowing water, further increase in weight losses with increasing flow duration. High water velocity causes increasing in weight losses and loss in gypsum content , more loss in weight and more loss in gypsum content, for all values of flow duration and water temperature. Unconfined compressive strength decreased during the soaking process and further decrease in strength with increasing soaking duration. The leaching effect causes a continuous increasing in the permeability value of unstabilized soil samples, while it has an insignificant effect on the permeability of lime stabilized soil samples. Leaching is a time-dependent process. The results showed that the pH values of natural and lime stabilized soil samples decreases during leaching process

Impact of Tufa Stone Powder as a Partial Replacement of Aggregate on the Mechanical Performance and Durability of Repair Mortar

The rehabilitation and reconstruction works are usually performed with a view to conserving these landmarks and maintaining them culturally, architecturally and structurally. From this perspective, the mortars utilized in these repairs must be suitable, physiochemically and mechanically, to the ancient materials used in these buildings. Accordingly, it was proposed to evaluate tufa stone powder, a waste product of one of the most widely found stones in the Loire Valley in France, as an ingredient in repair-work mortar mixtures (M1, M2) through partially replacing the fine aggregate it contains with different amounts of this powder (37%, 42%) by weight of mix. Additionally, a third manufacturing mortar (M3) was utilized with both prepared mortars (M1, M2) for comparison with the tufa stone. The mechanical properties (including flexural, compressive and shear strengths, and ultrasonic pulse velocity) and the durability properties (total porosity, thermal dilation and conductivity, capillary absorption, and water and gas permeability) of the three mortars were examined in addition to those of the tufa stone. The results revealed that the prepared mortar, M2, (having lower binder content and a higher amount of substitution with tufa stone powder) has the lowest mechanical performance in comparison with the other mortars, indicating that this mortar is more supple and loose than the authentic tufa masonry. The thermal and durability properties are comparable to that of the tufa stone existent in ancient monuments. Consequently, the prepared mortar (M2) is the most appropriate mortar, for utilization in repairing old landmarks in the Loire Valley in France

Mechanical Behavior of Gypseous Soil Treated with Lime

International audienc

Freezing–Thawing Behavior of Lime Treated Fine–grained Soil

International audienc

Adaptive task allocation for multi-UAV systems based on bacteria foraging behaviour

© 2019 Elsevier B.V. The foraging behaviour of bacteria in colonies exhibits motility patterns that are simple and reasoned by stimuli. Notwithstanding its simplicity, bacteria behaviour demonstrates a level of intelligence that can feasibly inspire the creation of solutions to address numerous optimisation problems. One such challenge is the optimal allocation of tasks across multiple unmanned aerial vehicles (multi-UAVs) to perform cooperative tasks for future autonomous systems. In light of this, this paper proposes a bacteria-inspired heuristic for the efficient distribution of tasks amongst deployed UAVs. The usage of multi-UAVs is a promising concept to combat the spread of the red palm weevil (RPW) in palm plantations. For that purpose, the proposed bacteria-inspired heuristic was utilised to resolve the multi-UAV task allocation problem when combating RPW infestation. The performance of the proposed algorithm was benchmarked in simulated detect-and-treat missions against three long-standing multi-UAV task allocation strategies, namely opportunistic task allocation, auction-based scheme, and the max-sum algorithm, and a recently introduced locust-inspired algorithm for the allocation of multi-UAVs. The experimental results demonstrated the superior performance of the proposed algorithm, as it substantially improved the net throughput and maintained a steady runtime performance under different scales of fleet sizes and number of infestations, thereby expressing the high flexibility, scalability, and sustainability of the proposed bacteria-inspired approach