Strength and durability characteristics of biopolymer-treated desert sand desert sand;bio-soil improvement;Xanthan gum;biopolymer;strength;durability; Biopolymer treatment of geomaterials to develop sustainable geotechnical systems is an important step towards the reduction of global warming. The cutting edge technology of biopolymer treatment is not only environment friendly but also has widespread application. This paper presents the strength and slake durability characteristics of biopolymer-treated sand sampled from Al-Sharqia Desert in Oman. The specimens were prepared by mixing sand at various proportions by weight of xanthan gum biopolymer. To make a comparison with conventional methods of ground improvement, cement treated sand specimens were also prepared. To demonstrate the effects of wetting and drying, standard slake durability tests were also conducted on the specimens. According to the results of strength tests, xanthan gum treatment increased the unconfined strength of sand, similar to the strengthening effect of mixing cement in sand. The slake durability test results indicated that the resistance of biopolymer-treated sand to disintegration upon interaction with water is stronger than that of cement treated sand. The percentage of xanthan gum to treat sand is proposed as 2-3% for optimal performance in terms of strength and durability. SEM analysis of biopolymer-treated sand specimens also confirms that the sand particles are linked through the biopolymer, which has increased shear resistance and durability. Results of this study imply xanthan gum biopolymer treatment as an eco-friendly technique to improve the mechanical properties of desert sand. However, the strengthening effect due to the biopolymer treatment of sand can be weakened upon interaction with water.

An earthwork design requires to consider the influence of severe climatic conditions on enduring performance of soils treated with chemical additives. This study was focused on investigating the mechanical behavior of a lime and cement-treated cohesive soil under the effects of repeated cycles of wetting and drying. The soil samples were prepared by adding different concentrations of cement (2, 6, 10, 12, 16, 20%) and quicklime (2, 4, 6, 8, 10%). Due to low-plastic nature of the host soil, the effectiveness of cement to reduce the plasticity of soil was relatively higher compared to lime-treatment. Likewise, an increase in optimum moisture and decrease in maximum dry unit weight was observed for both the additives and these effects were significant for lime treated soil compared to cement. Moreover, an increase in strength from 0.57 MPa to 12.9 MPa at 20% cement and from 0.57 MPa to 2.03 MPa at 2% lime was observed in unconfined compressive strengths (UCS) tests on soil samples. To investigate the durability characteristics of the treated soil, the samples were subjected to 12 cycles of wetting and drying with each cycle consisting of 5 hours of immersion in potable water and subsequent drying in oven for 43 hours. The compressive strength, volume change and weight loss of soil samples were determined at the 1st, 3rd, 6th, 9th and 12th cycle. It is observed that the durability behaviour of treated soil is multipart due to parallel processes of positive aging (hydration process associated with binding agents) and negative aging (induced weathering). For a sustainable mechanical performance of the treated soil, an optimum dose of 6% lime or 16% cement is recommended and some correlations are proposed to quantify the effects of repeated wetting and drying.

Over the past few decades, solid waste production, specifically construction waste, in Middle Eastern Arab countries has dramatically increased. This is characterized by several factors, including rapid urbanization, common food wasting habits, diverse culture, lack of proper planning of solid waste processes, insufficient equipment, as well as lack of proper funding. The exponential growth in solid waste generation rates has led to hazards to health and the environment, causing issues related to air and water pollution under the already increasing pressure of climate change. In this review, we analyze the current solid waste challenges in 13 Arab countries, common diseases, and actual projects applied. The selection of Arab countries was mainly based on the countries with the highest population as well as the availability of data in the field of study. This review also highlights the efforts of the Arab governments that implemented several pilot projects that are not sustainable or effective in the long term. We discuss the main issues facing each Arab country and the main challenges they have in common, as well as the potential to use the great amounts of construction waste in these countries. It is recommended that proper disposal and collection plans should be prioritized in the municipalities’ agendas since air and water pollution represent the main challenge in all Arab countries. Adequate treatment, recycling, and compost production facilities should be initiated and monitored regularly to take advantage of the relatively high percentage of organic matter in most Arab countries. Proper cooperation between the informal sector, private companies, and governments should be ensured in order to achieve long-term goals in the solid waste management (SWM) sector in MENA (Middle East and Northern Africa) Arab countries. This review provides a comprehensive study of the construction waste in MENA Arab countries that will help reach the goal of achieving sustainable countries.

Burnt clay brick is one of the oldest and most widely used construction materials. The production of burnt clay bricks with various waste materials can help reduce the environmental hazards and improve brick performance at low manufacturing costs, thereby leading towards more sustainable construction. This research aimed to evaluate the effect of using waste marble powder (WMP) in varying percentages, i.e., 0, 3, 6, 9, 12, and 15%, by weight of clay in an industrial brick kiln plant. A range of mechanical and durability tests was performed on the raw material, i.e., clay, WMP, and bricks, to quantify their performance. It was observed that incorporation of WMP resulted in a reduced unit weight of the bricks, making the structure lighter in weight. Moreover, compressive strength and freeze thaw test results for all the brick specimens and sulfate tests for the brick specimens with 12% WMP addition were within the Building Code of Pakistan, and ASTM C67 prescribed limits. Finally, it can be concluded that WMP up to 12% by weight of clay can be incorporated to prepare burnt clay bricks, which can reduce the environmental waste to achieve sustainability and economy for the brick industry.

Steel reinforcement corrosion in concrete structures such as bridges, industrial plants, marine structures, and coastal buildings is a growing concern due to its impact on cost, safety, and serviceability. Corrosion leads to spalling, cracking, and reduced reinforcement diameter, which can compromise structural integrity. This study examines the behavior of concrete columns with corroded reinforcement in two phases. In the first phase, 72 columns of 150 × 150 mm cross-sectional dimensions and 300 mm length were cast and subjected to an accelerated corrosion technique. The study examined variables such as concrete cover, concrete strength, and corrosion exposure. The second phase involved studying the axial behavior of corroded columns concerning the effect of column length. Column specimens of 150 × 150 mm cross-sectional dimensions and lengths of 500 mm, 700 mm, and 900 mm were cast, corroded, and tested under axial compressive load. The study revealed that a 30 mm concrete cover offers 10% more protection against corrosion than a 20 mm cover. Continuous exposure to a corrosive environment reduces the load-carrying capacity by 50%, while columns with 28 MPa concrete strength can carry 4% more load. Longer columns are more susceptible to corrosion, leading to a significant reduction in load-carrying capacity and concrete cover damage. Therefore, maintaining adequate concrete cover, strength, and regular inspections are essential to address steel reinforcement corrosion and preserve structural integrity.

The widespread availability of soft rocks and their increasing use as cheap rockfill material is adding more to geotechnical hazards because time-dependent granular decomposition causes significant damage to their mechanical properties. An experimental study was conducted through monotonic torsional shear tests on crushed soft rocks under fully saturated and dry conditions and compared with analogous tests on standard Toyoura sand. Due to the sensitivity of material to disintegration upon submergence, saturated conditions accelerated granular decomposition and, hence, simulated loss of strength with time, whereas, dry test condition represented the response of the soil with intact grains. A degradation index, in relation to gradation analyses after each test, was defined to quantify the degree of granular decomposition. Possible correlations of this index, with strength and deformation characteristics of granular soils, were explored. Enormous volumetric compression during consolidation and monotonic loading of saturated specimens and drastic loss of strength parameters upon submergence were revealed. It is revealed that the observed soil behaviour can be critical for embankments constructed with such rockfill materials. Moreover, the enhanced ability of existing soil mechanics models to predict time-dependent behaviour by incorporating water-induced granular decomposition can simplify several in situ geotechnical problems.