The utilization of natural fiber wastes could be an ideal way to tackle two problems. Firstly, this may be a solution to the issue of environmental challenges related to agricultural wastes. Secondly, it can potentially fix high-strength concrete's (HSC) issue of unexpected (sudden) collapse. This study looked at the results of using two different kinds of natural fiber waste in HSC. Seven HSC mixtures were manufactured; three included rice straw fibers (RSF), three contained palm leaf sheath fibers (PLSF), and one was a control mix (without fibers). In this research, the volume fractions of RSF and PLSF ranged from 1% to 3% and had an aspect ratio equal to 100. Different tests, including slump test, compressive strength, modulus of elasticity, flexural strength and tensile strength were conducted to determine their various properties. There were no significant improvements on compressive strength due to use of natural fiber while its tensile and flexural strengths increased particularly when including 1% RSF. RSF improved the properties of HSC more significantly than PLSF.
Reactive powder concrete (RPC) is one of the distinctive kinds of concrete whose benefits are high mechanical performance and durability. It contains a high content of cement, which means a high amount of carbon dioxide emitted during manufacturing. Scientists have tended to search for a way to reduce environmental damage, and one solution is to partially replace cement with mineral admixtures, waste from other industries, or by-products. There are restricted studies involving the use of high content of compounding mineral admixtures in the making of RPC. Therefore, this research aims to produce sustainable RPC with a low cement content (50%). The main objective of this research is to study the impact of substituting cement with 50% of silica fume (SF) + fly ash (FA) on the mechanical characteristics of RPC. Three mixtures containing various percentages of SF + FA were poured, in addition to the reference mixture. Flowability, flexural and compressive strengths, ultrasonic pulse velocity (UPV), and density were examined. The results showed that a sustainable RPC can be produced by substituting the cement with 10% SF and 40% FA with an improvement in workability and compressive strength and an insignificant reduction in other properties.
The rapid growth of population and consequent urgent need for building units have led to an increase in demand for the production of construction materials, including concrete. Traditionally, cement is the prime-type binder in concrete, and therefore, its production...
This analytical study aims to investigate the flexural behavior of simply supported RC beams having longitudinal hole with circle cross section under monotonic two point loads. The commercial FE program ABAQUS was used for simulating and implementing the specimens behavior that tested experimentally in previous researches. The overall specimens investigated were thirteen RC rectangular beam specimen, the first one was solid while the others with longitudinal circular hole. The specimens with holes divided into three groups, each one has a specified hole diameter 25 mm, 40 mm, and 50 mm. The distance from center of hole to the top section face was variable where the hole would be completely in the stress block, below it, or partially within it. The validity of the simulated model were verified by comparing the available load deflection data with the implemented one, where good agreement were noticed. The simulated models could introduce the ultimate load, first cracking load and its propagation in addition to the maximum attended deflection. It is concluded that the existence of a longitudinal hole with a percentage of diameter to beam depth ratio below 20% with different positions from top surface of the cross-section to the center of the hole values caused decreasing in ultimate load not exceeding 5% compared with the solid beam.
Increased rate of seizures and respiratory complications due to tramadol poisoning have been observed, even with first time of tramadol intake. So, the present work was used to investigate the clinical manifestations and laboratory investigations of acute tramadol toxicity and the correlation between toxic tramadol manifestations and blood tramadol level and laboratory parameters. A study was performed on 100 patients (80 males and 20 females) acutely intoxicated with tramadol, admitted to toxicology unit of Al-Azhar University Hospital (New Damietta) in the period from January to December 2017. Informed consent, urine sample was collected and 10 mL of blood was separated and used for extraction of tramadol residues by using a high-performance liquid chromatography (HPLC) and other blood samples were stored at-8°C for routine investigations. Then a detailed clinical examination was done to all patients. Generally, the frequency of seizures was (46 %) with acute tramadol poisoning. There was no correlation between blood tramadol level and toxic manifestations of tramadol poisoning. So, the frequency of seizures and toxic manifestations are not dosed dependent. Cannabis was the most common co-ingested drugs and adult males were more commonly affected by tramadol poisoning. It is recommended that the drug abuse problem must be treated at the level of community problems in order to minimize medical emergencies related to acute tramadol overdose occurring mostly by addiction and further studies should be proposed to extend our knowledge about relationships between sex and seizures among tramadol intoxicated patients
This research aims to develop sustainable high-strength concrete (SHSC) by replacing 100% fine and/or coarse aggregates with fine recycled aggregate (RA) and/or coarse RA. Due to the high surface water absorption of coarse RA, a surface treatment method was adopted, consisting of immersing it in a cement and silica fume slurry. Moreover, to improve the performance of the produced SHSC, steel fibers were employed at a relatively low volume fraction (0.5%). Eleven blends were cast and tested in this experimental study. A control SHSC mix (without RA) and ten other mixtures, including fine natural and RA, treated and untreated coarse RA, with and without steel fibers, were prepared. Compressive, splitting, and flexural strengths, water absorption, density, and ultrasonic pulse velocity (UPV) of the resulting SHSC were conducted. The results indicated that the use of RA in SHSC resulted in an average drop of 25% in its mechanical properties and an increase of about 30% in water absorption. However, using treated RA compensated the compressive and tensile strength reductions in SHSC by 9% and 7%, respectively, compared to mixes containing untreated RA. On the other hand, adding fibers helped improve compressive, flexural, and splitting tensile strengths by about 8%, 23%, and 31%, respectively, compared to the corresponding control mix. Consequently, the results showed that it is possible to produce durable SHSC made from 100% RA and 0.5% steel fibers with a reduced density and improved mechanical performance to a comparable level or even superior to high-strength concrete (HSC) with only natural aggregates (NAs).
Industrial waste is constantly increasing, so measures must be taken to recycle it in more practical and environmentally friendly ways. The aim of this study was to investigate the suitability of sawdust wasted particles for the production of cement bonded particleboards, and to enhance their compatibility with cement by using physical pretreatment processes, addition of nano slag and accelerated carbonation curing. All tests were carried out with different manufacturing parameters: sawdust/cement: (20%, 30% and 40%), treated and untreated wood, CO 2 curing and the addition of nano slag. Experiments were performed to assess the mechanical properties of produced particleboards such as density (D), water absorption (WA), thickness swelling (TS), bending strength (BS), and microstructural properties of the cement particleboards. For treated sawdust, the outcomes demonstrated an enhancement in the mechanical and microstructural characteristics of produced cement bonded particleboards by using the accelerated CO 2 curing method for sawdust particleboards. According to Scanning Electron Microscopy (SEM) micrographs, part of the carbonate crystals was found to be diffused into the cell walls and cavities and were found to protrude from sawdust surfaces.
Cement is considered a base material in preparing blending mixtures that applying in various projects in the civil engineering field. Nevertheless, the cement production process cause indubitable negative environmental influences such as emitting CO2. The production of cement produces around 7% of the global CO2 emissions. Thus, searching for alternate binders in building processes to minimise or substitute cement has been one of the social problems. A by-product or waste products are among the potential alternatives to the mentioned problem. The present investigation involves the consumption of paper sludge ash (PSA) waste as cement replacement to produce environmentally friendly, cementitious material. Limited studies were addressed the PSA grinding time impact on mortar or concrete properties. Moreover, limited studies replaced the cement with high volume of PSA. Therefore, during this study, the effect of grinding time and replacement level (up to 50%) of the PSA on the surface electrical resistivity and compressive strength of mortar were investigated. Three grinding periods (in addition to without grinding), two replacement levels and three testing ages were considered. The results indicated that grinding the PSA for 10 minutes and use it to replace up to 50% of the cement content have similar mechanical and durability performance to ordinary Portland cement after 28 curing days. This innovative binder will also cause a major difference in decreasing the building materials cost and CO2 emissions.
This study investigates the effectiveness of replacing the cement with 0, 5, 10, 15, and 20 wt.% of ceramic waste powder (HCCP) to improve the performance of recycled aggregate concrete (RCA) prepared using 25 wt.% wall tile ceramic coarse aggregates. The slump, initial and final setting time, compressive strength, splitting tensile strength, flexural strength, electrical resistivity, bulk density, porosity, total and surface water absorption, pH level, ultrasonic pulse velocity, dynamic elastic modulus, chloride ion diffusion coefficient, chloride penetration depth, microstructure analysis, and environmental assessment properties were investigated. The results showed that replacing cement with HCCP by 5 to 20 wt.% prolonged the setting time and improved all hardened properties. The highest improvements in mechanical properties were observed at 5 wt.% HCCP, with increasing rates of 26.5%, 22%, and 22.4% at 90 days for compressive strength, tensile strength, and flexural strength, respectively. On the other hand, the optimum enhancement for the durability, microstructural, and environmental efficiency properties was recorded at a 20 wt.% HCCP replacement rate. However, the strength at this ratio tended to decrease but remained higher than that of the control RAC. For instance, the total water absorption, surface water absorption, void ratio, chloride penetration depth, and migration coefficient were reduced by 47%, 45%, 38%, 62.3%, and 55.52%, respectively, compared to the reference sample.
Concrete is a constantly evolving building material whose demand is increasing due to population growth and urban development. This calls for more research on this composite material to improve its performance. However, concrete has some disadvantages, including that it is a brittle material and...
