Development of an Evaluation Protocol for Self-Cementing Secondary Road Base Materials

In congested areas around the world, traffic has significantly grown beyond expectation in terms of both volume and weight. Any hinder to the traffic causes severe delays resulting not only in economic loss but also in extra pollution of the environment. Therefore, the number of times maintenance work have to be performed should be reduced as much as possible. Application of self-cementing, secondary materials such as Blast Furnace Slag (BFS) for base courses is one of the methods to reduce the need for maintenance, since such base courses can provide an increase of the stiffness and the strength of the pavement structure. The long-term performance of this type of self-cementing, secondary material is however not fully understood. Because this type of stabilization appears to be associated with undesired deformations and distresses such as heaves formation and cracking. These undesired defects, which appear at random in terms of severity and moment of occurring, requires an assessment of the long-term physical and mechanical performance of these materials. However, long-term behaviour is often difficult to predict. In general, field-scale trials monitored over a long period of time, are needed to provide information whether these materials can be used without significant risk or not. As an alternative to field trials, which are time consuming and expensive, reliable methodologies are needed to estimate the long-term physical and mechanical performance within a short period of time. In this research, a protocol is proposed as a means of exploring the long-term mechanical and physical performance of secondary materials. A slag mixture which is routinely used in the Netherlands in road (sub-)bases was selected as study material. The slag mixture consisted of fresh Air-cooled Blast Furnace Slag (AC-BFS), steel slag and Granulated Blast Furnace Slag (GBFS) sand. The A32 motorway in the Netherlands was used as a source of field aged Blast Furnace Slag and steel slag materials. The pavement structure of this motorway experienced serious failure after about 20 years of service life and the base layer material caused this failure. In order to prevent similar problems to occur in the future, this research suggests different methods to detect at an early stage potential poor material performance. The first step of exploring the long-term performance of self-cementing materials in road applications implies obtaining a better understanding of the physical, mechanical and microstructural features of the materials when used as road base material and to analysis its possible effects on the pavement performance. Consequently, the influence of different potential degradation conditions, which can be mimicked in the laboratory was investigated. Numerous failure mechanisms have been hypothesized, including chemical reactions and increased stresses due to obstructed deformations. Additionally, other physical failure mechanisms including frost action damage were investigated. The results show that there is a linkage between the secondary material performance and temperature, moisture, chemical composition and time. The measured data indicate a relationship between some major chemical compositions and the mechanical properties of slags. The response of the laboratory prepared samples to the proposed tests were similar to the A32 base material failure, suggesting that the evaluation method did a reasonable job of producing in an accelerated way in the laboratory a material which behaves similar as the A32 material. The developed procedure (protocol) suggests that it is possible on the basis of material characterization, steam aging tests and freezing – thawing tests to trace in a rather short period of time materials which may attribute to the failure process of base layers in pavements.Structural EngineeringCivil Engineering and Geoscience

Effect of 8 weeks Resistance Training on BDNF and TrkB in the Hippocampus of Adult Male Rats

Background & aim: Exercise enhances the synaptic plasticity and neuroprotective effects in the adult brain. However, it remains unknown that how plasticity molecules change following types of training. The purpose of this study was to determine the effect of eight weeks resistance training on protein levels of Brain Derived Neurotrophic Factor(BDNF) and receptor of TrkB, in the hippocampus of adult male rats. Methods: In this experimental study, twelve adult male rats, 8 weeks of age, with an average weight of 200 to 225 grams were randomly divided into two groups, control and exercise respectively. The exercise was to increase the weight on the ladder. 24 hours after their last training session. The animals were killed and the hippocampus was removed for further testing. ELISA determined changes in protein levels. Data were analyzed by independent t test. Results: There was a significant difference between train and control groups In protein level of variables statically (p≤0.05). In addition, protein levels of BDNF and TrkB in the hippocampus of rats increased. Conclusion: Resistance training is beneficial for promoting hippocampal plasticity associated with BDNF signaling and consequently functional and cognitive benefits

Application of aging methods to estimate long term performance of secondary materials for road construction

Long term performance of secondary materials is becoming a challenging aspect in road construction since due to their benefits they are being used on a large scale, but on the other hand their future behaviors are difficult to estimate. In this study, aging is proposed as a means of exploring the long-term mechanical and physical performance of secondary materials. A Blast Furnace Slag (BFS) mixture which is routinely used in the Netherlands in road (sub-) base construction was selected as a reference material. The A32 motorway in the Netherlands was used as a source of field aged granulated BFS materials. The base layer of this motorway, suddenly experienced serious failure. Different failure mechanisms have been hypothesized. In order to estimate future behavior of secondary materials and to prevent similar problems to occur an aging protocol was suggested to detect at an early stage potential poor material performance. Two types of aging approaches were chosen and applied to the field aged and fresh materials being steam aging and cyclic freezing and thawing. Both aging treatments have affected mechanical and chemical characteristics. The study of response variables showed there is a linkage between compressive strength, expansion, micro cracking and amount and type of binder.Structural EngineeringCivil Engineering and Geoscience

Verification of Experimentally Determined Permeability and Form Coefficients of Al2O3 Ceramic Foam Filters (CFF) at High and Low Flow Velocity Using a CFD Model

Filtration using Ceramic Foam Filters (CFFs) is a method widely used to separate inclusions from molten aluminium. In the present work, the specific permeability and form drag coefficients of nominal 50 mm thick commercial Al2O3-based CFFs, of grades 30, 50, 65 and 80, have been calculated from pressure drop experiments using high (60–500 mm s−1) and low (0.2–10 mm s−1) water velocities. Moreover, 2D axial symmetric Computational Fluid Dynamic (CFD) models have been developed, using COMSOL Multiphysics® to validate the experimental results. The empirically obtained values were defined as global parameters used to model the pressure, as well as the velocity fields in the water pipes and in the CFFs. The modelled pressure drop over the filter thickness for the high water velocity experiments showed < ± 1% deviation from the corresponding experimental results for all CFF grades. Moreover, the developed model also showed good agreement with the experimental results obtained from the low water velocity experiments, where the deviation of the pressure drop for the CFF samples of grade 30, 50 and 65 were ≤ ± 4.6% and for CFF samples of grade 80 ≤ ± 13.4%

Transcranial photobiomodulation in the management of brain disorders

Transcranial photobiomodulation (tPBM) is the process of delivering light photons through the skull to benefit from its modifying effect. Brain disorders are important health problems. The aim of this review was to determine the existing evidence of effectiveness, useful parameters, and safety of tPBM in the management of traumatic brain injury, stroke, Parkinson, and Alzheimer's disease as the common brain disorders. Four online databases, including Cochrane, Pub Med, Embase, and Google scholar were searched according to the Preferred Reporting Items for Systematic Reviews and meta-analyses (PRISMA) guidelines. 4728 articles were obtained in the initial search. Only those articles that were published until September 2020 and designed as randomized clinical trials (RCTs) or animal-controlled studies were included. 6 RCTs, 2 related supplementary articles, and 38 controlled animal studies met the inclusion criteria of this study. No RCTs were performed in the fields of Alzheimer's and Parkinson's diseases. The human RCTs and animal studies reported no adverse events resulted from the use of tPBM. Useful parameters of tPBM were identified according to the controlled animal studies. Since the investigated RCTs had no homogenous results, making an evidence-based decision for definite therapeutic application of tPBM is still unattainable. Altogether, these data support the need for large confirmatory well-designed RCTs for using tPBM as a novel, safe, and easy-to-administer treatment of brain disorders. Evidence before this study: High prevalence and complications of brain disorders and also side effects of neuropsychiatric medications have encouraged researchers to find alternative therapeutic techniques which tPBM can be one of them. In present review we tried to determine the existing evidence of effectiveness, useful parameters, and safety of tPBM in the management of traumatic brain injury, stroke, Alzheimer, and Parkinson's disease as common brain disorders. Four online databases, including �Cochrane�, �Pub Med�, �Embase�, and �Google scholar� were searched. Only those articles that were published until September 2020 and designed as RCTs or animal-controlled studies were included. Search keywords were the followings: transcranial photobiomodulation� OR �transcranial low-level laser therapy� AND �stroke� OR �traumatic brain injury� OR �Alzheimer� OR �Parkinson�. Several studies have confirmed effectiveness of tPBM in treatment of different brain disorders but the level of evidence of its effectiveness remain to be determined. Added value of this study: In this study we systematically reviewed human RCTs to determine the existing evidence of tPBM effectiveness in management of four mentioned brain disorders. Since the outcomes of the reviewed RCTs were not homogeneous, further well-designed RCTs are required to decide more definitively on the evidence of this noninvasive and probably safe therapeutic intervention. We hypothesized that non-homogeneous outcomes could be due to inefficiency of PBM parameters. Controlled animal studies have the advantage of using objective tests to evaluate the results and compare them with the control group. We determined useful tPBM parameters based on these studies. Implications of all the available evidence: This research is part of our main project of tinnitus treatment using photobiomodulation (PBM). Evidence of central nervous system involvement in tinnitus led us to believe that treatment protocol of tinnitus should also include transcranial PBM. The determined useful parameters can be helpful in designing more efficient tPBM protocols in the management of brain disorders and tinnitus as a common debilitating symptom that can be associated with these disorders. © 202

Characterization of Blast Furnace Slag to be used as Road Base Material

In congested areas around the world, traffic has significantly grown beyond expectation both in terms of volume and weight. Any hinder to the traffic causes severe delays resulting not only in economic loss but also in extra pollution of the environment. Therefore, maintenance works are desired to be reduced as much as possible. Application of self-cementing materials such as Blast Furnace Slag (BFS) for base courses is one of the methods to reduce the need for maintenance, since such base courses can provide a significant increase of the stiffness and the strength of the pavement structure. However, this type of stabilization appears to be associated with undesired deformations and distresses such as heaves formation and cracking that occurred, e.g. on the A32 motorway in the Netherlands. Different failure mechanisms have been hypothesized. This means, the use of BFS in a road (sub-)base layer requires a good knowledge of its characteristics. This paper presents data on the chemical and mineralogical characteristics of fresh and field aged BFS materials from a case study in the Netherlands. Furthermore a microstructural study was done on samples which have experienced freezing and thawing cycles.Structural EngineeringCivil Engineering and Geoscience