Non-destructive evaluation of reclaimed asphalt cement concrete

Reclaimed asphalt (RA) has been increasingly used as an alternative aggregate in the manufacture of low to medium strength cement concrete. It is the aim here to investigate the behaviour and properties of concrete made with RA, using ultrasonic pulse velocity (UPV). Most previous investigations using UPV have been into gravel concrete starting between 1–7 days and up to 28 days. In this research, the application of UPV has been extended to cement concrete made with RA aggregate at the very early age, taken here as the period starting immediately after concrete mixing and up to 28 days. An early age test system for continuous ultrasonic monitoring of fresh concretes has been used to assess important properties, such as early age strength, using UPV measurements. Concrete mixes with different water/cement ratios (.4–.7) were used. Empirical models have been produced relating compressive strength and UPV for early age RA concrete

Improving the strength properties of recycled asphalt aggregate concrete

The querying of aggregate, for use in the manufacture of concrete, can have adverse environmental and ecological effects. The replacement of gravel aggregate with recycled (reclaimed) asphalt would help in the reduction of these effects. It can also help in reducing the quantity of recycled asphalt obtained from road re-surfacing that would otherwise be disposed of in landfill sites. The applications of concrete containing recycled asphalt have been very limited due to its low strength. This study investigates the feasibility of improving the strength of recycled asphalt concretes. This would increase the potential for using this type of concrete as an alternative to normal concrete, especially where medium strengths might be required. Concrete strength improvements would be achieved by changing the surface characteristics of recycled asphalt aggregate. This has been sought by using two methods; mechanical roughening and chemical solvent etching. It has been possible to improve the strength of concrete containing recycled asphalt to values similar to that of normal (gravel) concrete, by applying the mechanical roughening technique. Chemical etching has no effect on strength improvement of the concrete. The concretes have also been tested using non-destructive methods in the form of ultrasonic pulse velocity and rebound number. The effects of replacing gravel with different percentages of recycled asphalt on the strength, pulse velocity, and surface hardness of concrete are considered initially. The inclusion of recycled asphalt at 25% has resulted in the reduction of strength. The strength decreases further with an increase in the percentage (up to 100%) of recycled asphalt. All investigations were performed on early age concrete (1–28 days)

Eggshell and Walnut Shell in Unburnt Clay Blocks

Agricultural residues/by-products have become a popular choice for the manufacturing of building materials due to their cost-effectiveness and environmental friendliness, making them a viable option for achieving sustainability in the construction sector. This study addresses the utilisation of two agro-wastes, i.e., eggshell and walnut shell, in the manufacture of unburnt clay blocks. The experiments were carried out on three series of samples in which first eggshell (10–50%) and walnut shell (5–20%) were incorporated individually and then combined (5% walnut, 10–30% eggshell) in the mixture to assess their influences on the physical and mechanical properties of the unburnt clay blocks. This study performed the following tests: Density, capillary water absorption, linear shrinkage, flexural and compressive strength. The results indicated that eggshell enhanced the strength relative to the control sample when the materials were employed individually, but walnut shell lowered it. Moreover, combining the two materials in the mixer reduced the strength of the samples even further. Nevertheless, the inclusion of the waste materials decreased the density, capillary water absorption coefficient and linear shrinkage of the samples. The findings indicate that eggshell has great potential for unburnt clay block manufacture. However, walnut shell integration needs further research

Friction and Wear Performance Evaluation of Bio-Lubricants and DLC Coatings on Cam/Tappet Interface of Internal Combustion Engines.

The environmental concerns associated with artificially formulated engine oils have forced a shift towards bio-based lubricants. The deposition of hard coatings on engine components and migrating to environmentally friendly green lubricants can help in this regard. Chemically modified forms of vegetable oils, with better low-temperature characteristics and enhanced thermo-oxidative stability, are suitable substitutes to conventional lubricant base oils. The research presented in this manuscript was undertaken to experimentally investigate the wear and friction performance of a possible future generation of an environmentally friendly bio-based lubricant as a potential replacement for conventional engine lubricants. In order to quantify the tribological benefits which can be gained by the deposition of DLC coatings, (an (a-C:H) hydrogenated DLC coating and an (a-C:H:W) tungsten-doped DLC coating) were applied on the cam/tappet interface of a direct acting valve train assembly of an internal combustion engine. The tribological correlation between DLC-coated engine components, lubricant base oils and lubricant additives have been thoroughly investigated in this study using actual engine operating conditions. Two additive-free base oils (polyalphaolefines (PAO) and chemically-modified palm oil (TMP)) and two multi-additive-containing lubricants were used in this investigation. Real-time drive torque was measured to determine the friction force, detailed post-test analysis was performed, which involved the use of a specialized jig to measure camlobe wear. An optical profilometer was used to measure the wear on the tappet, high-resolution scanning electron microscopy was employed to study the wear mechanism and energy-dispersive X-ray spectroscopy was performed on the tested samples to qualitatively access the degradation of the coating. When using additive-free TMP, a low friction coefficient was observed for the cam/tappet interface. The presence of additives further improved the friction characteristics of TMP, resulting in reduced average friction torque values. A tremendous enhancement in wear performance was recorded with a-C:H-coated parts and the coating was able to withstand the test conditions with little or no delamination

Influence of Sawdust Particle Sizes on the Physico-Mechanical Properties of Unfired Clay Blocks

Sawdust, which is a waste/by-product of the wood/timber industry, can be utilised as a valuable raw material in building material production due to its abundance and low cost. However, the application of sawdust in the manufacture of unfired clay blocks has received little investigation. Furthermore, the impact of different sawdust particle sizes on the properties of unfired clay blocks has not been studied. Therefore, this study screened sawdust at three different particle sizes: SP-a (212 μm < x < 300 μm), SP-b (425 μm < x < 600 μm) and SP-c (1.18 mm < x < 2.00 mm), to examine their effects on the physical and mechanical properties of unfired clay blocks. The density, linear shrinkage, capillary water absorption and flexural and compressive strengths were among the tests performed. Different sawdust percentages, i.e., 2.5%, 5%, 7.5% and 10% of the total weight of the clay, were considered. The tests results show that when sawdust was added to the mixture, the density of the samples reduced for all particle sizes. However, the linear shrinkage increased in SP-a samples but decreased in the other two particle size samples as the sawdust percentage increased from 2.5% to 10%. On the other hand, the capillary water absorption coefficient increased while the strength decreased with increasing sawdust content for all three groups. The highest compressive strength (CS) and flexural strength (FS) were achieved at 2.5% of sawdust content. Furthermore, it was observed that SP-b (CS—4.74 MPa, FS—2.00 MPa) samples showed the highest strength followed by SP-a (CS—4.09 MPa, FS—1.69 MPa) and SP-c (CS—3.90 MPa, FS—1.63 MPa) samples. Consequently, good-quality unfired clay blocks can be manufactured using sawdust up to 2.5% with particle sizes ranging between 600 and 425 μm

Thermophysical Properties of Sawdust and Coconut Coir Dust Incorporated Unfired Clay Blocks

Sawdust and coconut coir dust are agro-wastes/by-products which are suitable for use as raw materials to manufacture unfired clay blocks due to their excellent physical and mechanical properties. A limited number of studies have been conducted on the utilisation of these agro-wastes in clay block production, and they have mostly been devoted to investigating the physicomechanical properties, with less attention given to the thermal properties. Moreover, the majority of the studies have used chemical binders (cement and lime) in combination with agro-waste, thus increasing the carbon footprint and embodied energy of the samples. Furthermore, no research has been performed on the thermal performance of these agro-wastes when incorporated into clay blocks at the wall scale. Therefore, to address these limitations, the present study developed unfired clay blocks incorporating sawdust and coconut coir dust (0, 2.5, 5, and 7.5% by weight), without the use of chemical binders, and evaluated their thermal performance, both at the individual and wall scales. The experiments were divided into two phases. In the first phase, individual sample blocks was tested for basic thermal properties. Based on the results of the first phase, small walls with dimensions of 310 mm × 215 mm × 100 mm were built in the second phase, using the best performing mixture from each waste type, and these were assessed for thermal performance using an adapted hot box method. The thermal performance of the walls was evaluated by measuring the heat transfer rate from hot to cold environments and comparing the results to the reference wall. The results showed that thermal conductivity decreased from 0.36 W/mK for the reference sample, to 0.19 W/mK for the 7.5% coconut coir dust sample, and 0.21 W/mK for the 7.5% sawdust sample, indicating an improvement in thermal insulation. Furthermore, the coconut coir dust and sawdust sample walls showed a thermal resistance improvement of around 48% and 35%, respectively, over the reference sample wall. Consequently, the findings of this study will provide additional essential information that will help in assessing the prospective applications of sawdust and coconut coir dust as the insulating material for manufacturing unfired clay blocks

Production of Ternary Blend Binder as an Alternative to Portland Cement

Environmental pollution and the relatively high cost of waste disposal have been a major focus for scientists around the world, leading researchers to find a solution to reuse waste materials in different applications. Additionally, landfills are considered one of the biggest crisis facing the Iraqi government. Therefore, this study aims to present a new ternary mixture that consists of OPC in addition to Pulverized Fuel Ash (PFA), Ground Granulated Blast Furnace Slag (GGBS) by utilizing it as a partial substitution of cement. A new ternary mortar mixtures containing four substitution levels of cement with GGBS and PFA (0%, 30 %, 50% and 70% by weight) were carried out. The Ultrasonic Pulse Velocity (UPV) and compressive strength tests were adopted to show the influence of GGBS and PFA on mechanical features of cement mortar. Findings indicated that, the compressive strength values were reduced with increasing the GGBS and PFA proportions at all curing ages. For 70% replacement, the compressive strength values were the lowest values comparison with that for control specimens. In contrast, the GGBS and PFA had a negative and positive impacts on the UPV of mortar depending on the substitution ratio. At 30 % substitution levels, the velocity value was enhanced, while other substitution ratios affected negatively on the UPV values

The Impact of Using Different Ratios of Latex Rubber on the Characteristics of Mortars Made with GGBS and Portland Cement

Preserving natural resources and implementing the concepts of sustainable engineering to approach the zero waste concept helped in reducing the detrimental environmental effects in the last two-decade. Proposed re-using of Ground Granulated Blast Furnace Slag (GGBS) as an alternate solution is to get rid of them and profit from them concurrently. In this process, GGBS is used as cement substitute material to enhance mortar characteristics. On the other hand, the required water for concrete mixture should be characterized by several characters, which similar to drinkable water, therefore, using of Latex Rubber as a water substitution reduces the demand for such water in the construction industry. In this project, percentages of GGBS that have been used were 0%, 10%, 30%, and 50% which compatible with (0, 10, 20 and 30) % of Latex Rubber. Suitable tests were performed to measure properties of mortar by GGBS and Latex Rubber such as setting time, compressive strength and Permeability test (Electrical resistivity). The results obtained indicate that the setting time reduced with increasing Rubber Latex in spite of increasing the proportion of water to binder. Additionally, increasing the Latex Rubber amount leads to decrease the compressive strength and electrical resistivity of mortars

Influence of acute pancreatitis on the in vitro responsiveness of rat mesenteric and pulmonary arteries

<p>Abstract</p> <p>Background</p> <p>Acute pancreatitis is an inflammatory disease characterized by local tissue injury and systemic inflammatory response leading to massive nitric oxide (NO) production and haemodynamic disturbances. Therefore, the aim of this work was to evaluate the vascular reactivity of pulmonary and mesenteric artery rings from rats submitted to experimental pancreatitis.</p> <p>Male Wistar rats were divided into three groups: saline (SAL); tauracholate (TAU) and phospholipase A₂(PLA₂). Pancreatitis was induced by administration of TAU or PLA₂from <it>Naja mocambique mocambique </it>into the common bile duct of rats, and after 4 h of duct injection the animals were sacrificed. Concentration-response curves to acetylcholine (ACh), sodium nitroprusside (SNP) and phenylephrine (PHE) in isolated mesenteric and pulmonary arteries were obtained. Potency (pEC₅₀) and maximal responses (E_MAX) were determined. Blood samples were collected for biochemical analysis.</p> <p>Results</p> <p>In mesenteric rings, the potency for ACh was significantly decreased from animals treated with TAU (about 4.2-fold) or PLA₂(about 6.9-fold) compared to saline group without changes in the maximal responses. Neither pEC₅₀nor E_MAXvalues for Ach were altered in pulmonary rings in any group. Similarly, the pEC₅₀and the E_MAXvalues for SNP were not changed in both preparations in any group. The potency for PHE was significantly decreased in rat mesenteric and pulmonary rings from TAU group compared to SAL group (about 2.2- and 2.69-fold, for mesenteric and pulmonary rings, respectively). No changes were seen in the E_MAXfor PHE. The nitrite/nitrate (NO_x^-) levels were markedly increased in animals submitted to acute pancreatitis as compared to SAL group, approximately 76 and 68% in TAU and PLA₂protocol, respectively.</p> <p>Conclusion</p> <p>Acute pancreatitis provoked deleterious effects in endothelium-dependent relaxing response for ACh in mesenteric rings that were strongly associated with high plasma NO_x^-levels as consequence of intense inflammatory responses. Furthermore, the subsensitivity of contractile response to PHE in both mesenteric and pulmonary rings might be due to the complications of this pathological condition in the early stage of pancreatitis.</p

Overview SARS-CoV-2 Pandemic as January-February 2022: Likely Cometary Origin, Global Spread, Prospects for Future Vaccine Efficacy

Copyright © The Athors 2022. As the SARS-CoV-2 pandemic is nearing its eventual end we focus on what we believe are two key omissions from the mainstream scientific literature and which have significant implications for how mankind manages the next global pandemic. We therefore review data, observations, analyses and conclusions from our series of papers published through 2020 and 2021 on its likely cometary origin and global spread. We also revisit our long held understanding of the superior effectiveness of intra-nasal vaccines against respiratory tract pathogens that involve induction of dimeric secretory IgA antibodies. While these two oversights seem disparate, together they provide us with new insights into our collective awareness of how we might view and address the next global pandemic. We begin with our hypothesis of the likely cometary origin of the SARS-CoV-2 virus via a bolide strike in the stratosphere on the night of October 11 2019 on the 40o N line over Jilin in NE China. Further global spread most likely occurred via prevailing wind systems transporting both the pristine cometary virus followed by continuing strikes from the same primary source as well as prior human-passaged virus transmitted by person to person spread and through contaminated dust in global wind systems. We also include a discussion of our prior work on data relating to vaccine protective efficacy. Finally we review the totality of evidence concerning the likely origin and global spread of the predominant variants of the virus ‘Omicron’ (+Delta mix?) from early to mid-December 2021 and extending into the first week January 2022. We describe the striking data showing the large numbers of infectious cases per day and outline the scale of what appears to be a global pandemic phenomenon, the causes of which are unclear and not completely understood. Firstly, these essentially simultaneous and sudden global-wide epidemic COVID-19 out breaks, appear to be largely correlated with events external to the Earth, probably causing globally correlated precipitation events. They appear related broadly to “Space Weather” events that render the Earth vulnerable to cosmic pandemic pathogen attack particularly during times of the minima of the Sunspot Solar Cycle which we are now currently passing through. Secondly, we argue that these sudden global-wide epidemic outbreaks of COVID-19 are specifically largely influenced by global wind transport and deposition mechanisms, the physics of which we need to further explore and comprehend. We conclude on an optimistic note for mankind. Given our prior knowledge of the effectiveness against respiratory tract pathogens of mucosal immunity involving induction of dimeric secretory IgA antibodies, we consider that the recently published intra-nasal vaccine data from laboratories based at the University of California, San Francisco and, independently at Yale University. These latter studies hold out great promise for the future development of both pan-specific and specific immunity against future pandemics caused by suddenly emergent respiratory pathogens, whether viral, bacterial or fungal