Sustainable strength improvement of soft clay stabilized with two sizes of recycled additive

High amounts of ceramic waste is accumulated every year in the disposal and construction sites due to the rejection of all smashed, cracked, and broken tiles. The usage of recycled ceramic crushed tiles (RCT) in improving soft soil is considered an environmentally-friendly, economical and sustainable solution. Soft soils are characterized as problematic soils that are always associated with weak performance when loaded. It is a common practice to excavate, transport and dispose this kind of soil into landfills and replace it with a soil that meets the engineering requirements. Due to shortage of space in landfills and the high costs involved in this processes, soft soils are always treated at construction sites. In this study, two sizes of RCT (0.3 and 1.18 mm) are used to improve the physical and mechanical properties of soft soil. The size and percentage of RCT are investigated and its influence on unconfined compressive strength (UCS) and compaction is evaluated. Microstructural tests included scanning electron microscopic (SEM) and energy dispersive X-ray spectroscopy (EDS) were also conducted on samples treated with RCT. Noticeable increment in both density and unconfined compressive strength was achieved. The maximum dry density increased from 1.59 Mg/m3 to 1.82 Mg/m3 and 1.77 Mg/m3 at the addition of 40% 1.18 mm and 0.3 mm RCT, respectively. Whereas the unconfined compressive strength increased from 50 kPa to 250 kPa and 225 kPa at 10% addition of 1.18 mm RCT and 40% 0.3 mm RCT, respectively. The optimum value of RCT to treat soft clay was found to be 10% and 40% for 1.18 mm and 0.3 mm RCT, respectively. The remarkable improvement in the strength of soil is due to the development of cementation compounds that acts as a binder between the RCT and soil particles. This study would help in reducing the impacts created by disposing of both problematic soil and waste tiles. Besides, cement is the most traditional material used to stabilize soil. This research would contribute to reducing the CO2 produced during the production of cement

Risk-based prioritization of pharmaceuticals in the natural environment in Iraq

Numerous studies have demonstrated the occurrence of pharmaceuticals in the natural environment, raising concerns about their impact on non-target organisms or human health. One region where little is known about the exposure and effects of pharmaceuticals in the environment is Iraq. Due to the high number of pharmaceuticals used by the public health sector in Iraq (hospitals and care centres) and distributed over the counter, there is a need for a systematic approach for identifying substances that should be monitored in the environment in Iraq and assessed in terms of environmental risk. In this study, a risk-based prioritization approach was applied to 99 of the most dispensed pharmaceuticals in three Iraqi cities, Baghdad, Mosul and Basrah. Initially, information on the amounts of pharmaceuticals used in Iraq was obtained. The top used medicines were found to be paracetamol, amoxicillin and metformin with total annual consumption exceeding 1000 tonnes per year. Predicted environmental concentrations (PECs) and predicted no-effect concentrations (PNECs), derived from ecotoxicological end-points and effects related to the therapeutic mode of action, were then used to rank the pharmaceuticals in terms of risks to different environmental compartments. Active pharmaceutical ingredients used as antibiotics, antidepressants and analgesics were identified as the highest priority in surface water, sediment and the terrestrial environment. Antibiotics were also prioritized according to their susceptibility to kill or inhibit the growth of bacteria or to accelerate the evolution and dissemination of antibiotic-resistant genes in water. Future work will focus on understanding the occurrence, fate and effects of some of highly prioritized substances in the environment

Targeting neuroinflammation for therapeutic intervention in neurodegenerative pathologies: A role for the peptide analogue of thymulin (PAT)

Introduction: Inflammation has a vital task in protecting the organism, but when deregulated, it can have serious pathological consequences. The central nervous system (CNS) is capable of mounting immune and inflammatory responses, albeit different from that observed in the periphery. Neuroinflammation, however, can be a major contributor to neurodegenerative diseases and constitute a major challenge for medicine and basic research. Areas covered: Both innate and adaptive immune responses normally play an important role in homeostasis within the CNS. Microglia, astrocytes and neuronal cells express a wide array of toll-like receptors (TLR) that can be upregulated by infection, trauma, injuries and various exogenic or endogenic factors. Chronic hyper activation of brain immune cells can result in neurotoxic actions due to excessive production of several pro-inflammatory mediators. Several studies have recently described an important role for targeting receptors such as nicotinic receptors located on cells in the CNS or in other tissues for the control of inflammation. Expert opinion: Thymulin and its synthetic peptide analogue (PAT) appear to exert potent anti-inflammatory effects at the level of peripheral tissues as well as at the level of the brain. This effect involves, at least partially, the activation of cholinergic mechanisms. © 2012 Informa UK, Ltd

Cyclic behavior of RT-cement treated marine clay subjected to low and high loading frequencies

The weakening and softening behavior of soft clay subjected to cyclic loading due to the build-up of excess pore water pressure is well-known. During the design stage of the foundation of highways and coastal high-rise buildings, it is important to study the mechanical behavior of marine soils under cyclic loading as they undergo greater settlement during cyclic loading than under static loading. Therefore, this research evaluates the cyclic stress-strain and shear strength of untreated and treated marine clay under the effects of wind, earthquake, and traffic loadings. A series of laboratory stress-controlled cyclic triaxial tests have been conducted on both untreated and treated marine clay using different effective confining pressures and a frequency of 0.5 and 1.0 Hz. In addition, treated samples were cured for 28 and 90 days and tested under a frequency of 2.0 Hz. The results revealed significant differences in the performance of treated marine clay samples than that of untreated samples under cyclic loading. The treated marine clay samples were able to stand up to 2000 loading cycles before failure, while untreated marine clay samples could not stand few loading cycles. The untreated marine clay displayed a higher permanent axial strain rate under cyclic loading than the treated clay due to the existence of new cementing compounds after the treatment with recycled tiles and low amount (2%) of cement. The effect of the effective confining pressure was found to be significant on untreated marine clay while its effect was not crucial for the treated samples cured for 90 days. Treated samples cured for 90 days performed better under cyclic loading than the ones cured for 28 days and this is due to the higher amount of cementitious compounds formed with time. The highest deformation was found at 0.5 Hz, which cannot be considered as a critical frequency since smaller frequencies were not used. Therefore, it is recommended to consider testing the treated marine clay using smaller frequencies than 0.5 Hz

Undrained shear strength and microstructural characterization of treated soft soil with recycled materials

Waste materials are being produced in huge quantities globally, and the usual practice is to dump them into legal or illegal landfills. Recycled tiles (RT) are being used in soil stabilisation which is considered as sustainable solution to reduce the amount of waste and solve the geotechnical problems. Although the stabilisation of soil using RT improved the soil properties, it could not achieve the standard values required for construction. Thus, this study uses 20% RT together with low cement content (2%) to stabilise soft soil. Series of consolidated undrained triaxial compression tests were conducted on untreated and RT-cement treated samples. Each test was performed at 7, 14, and 28 days curing period and 50, 100, and 200 kPa confining pressures. The results revealed an improvement in the undrained shear strength parameters (cohesion and internal frication angle) of treated specimens compared to the untreated ones. The cohesion and friction angle of the treated samples were increased with the increase in curing time and confining pressure. The peak deviator stress of treated samples increases with the increment of either the effective confining pressures or the curing period. Microstructural and chemical tests were performed on both untreated and RT-cement treated samples, which included field emission scanning electron microscopic (FESEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and energy dispersive X-ray spectrometer (EDX). The results indicated the formation of cementation compounds such as calcium aluminium hydrate (C-A-H) within the treated samples. Consequently, the newly formed compounds were responsible for the improvement observed in the results of the triaxial tests. This research promotes the utilisation of RT to reduce the amount of cement used in soil stabilisation for cleaner planet and sustainable environment

Degradation of limestone exposed to drying and wetting cycles experimental study

Degradation of rock is the deterioration of the rock forming materials and the reduction of strength and stiffness within time. It is responsible for the failure of rock slopes and landslides as the drying and wetting cycles in long-term will extensively reduce the strength of the rock and eventually end up as a soil-like material. Weathering rate is very crucial, and it is the main parameter inducing and accelerating degradation of rock. This study focuses on investigating and evaluating the effect of degradation on cored samples of limestone. Limestone was collected from the state of Perak, Malaysia and the samples were cored, trimmed and cut into 50 mm diameter and 80 mm height. A total number of 30 samples were exposed to different number of drying and wetting cycles in the laboratory. A total number of 27samples were tested using the Uniaxial compression test after 0 - 14 cycles while three samples were exposed to exactly 14 cycles to observe the reduction in weight. The results showed the strength of limestone to decrease gradually with the increment of drying and wetting cycles. Besides, samples that were continuously exposed to 14 drying and wetting cycles experienced a weight reduction of approximately 1.12%

Mechanical behaviour of waste powdered tiles and portland cement treated soft clay

The main objective of this study is to evaluate and compare the efficiency of ordinary Portland cement (OPC) inenhancing the unconfined compressive strength of soft soil alone and soft soil mixed with recycled tiles. The recycled tiles havebeen used to treat soft soil in a previous research by Al-Bared et al. (2019) and the results showed significant improvement, butthe improved strength value was for samples treated with low cement content (2%). Hence, OPC is added alone in this researchin various proportions and together with the optimum value of recycled tiles in order to investigate the improvement in thestrength. The results of the compaction tests of the soft soil treated with recycled tiles and 2, 4, and 6% OPC revealed anincrement in the maximum dry density and a decrement in the optimum moisture content. The optimum value of OPC wasfound to be 6%, at which the strength was the highest for both samples treated with OPC alone and samples treated with OPCand 20% recycled tiles. Under similar curing time, the strength of samples treated with recycled tiles and OPC was higher thanthe treated soil with the same percentage of OPC alone. The stress-strain curves showed ductile plastic behaviour for theuntreated soft clay and brittle behaviour for almost all treated samples with OPC alone and OPC with recycled tiles. Themicrostructural tests indicated the formation of new cementitious products that were responsible for the improvement of thestrength, such as calcium aluminium silicate hydrate. This research promotes recycled tiles as a green stabiliser for soilstabilisation capable of reducing the amount of OPC required for ground improvement. The replacement of OPC with recycledtiles resulted in higher strength compared to the control mix and this achievement may results in reducing both OPC in soilstabilisation and the disposal of recycled tiles into landfills