Effect of Partial Replacements of Coarse Aggregate by Polycarbonate Plastic Waste on the First Crack Impact Resistance of Concrete Beam

This paper examines impact strength properties of concrete in which different amounts 2.5%, 5% and 10% of polycarbonate plastic waste particles were used as coarse aggregate replacement. For each amount, six beams of 100 mm ×100 mm × 500mm were subjected to 4.5 kg hammer from 457 mm height. The number of blows of the hammer required to induce the first visible crack of the beams were recorded. The results are presented in terms of impact energy required for the first visible crack. The concrete mixtures exhibited ability to absorb a large amount of impact energy. The polycarbonate plastic waste increased the first crack impact energy of concrete. Keywords: Polycarbonate plastic waste; Cement concrete; Compressive strength; First crack impact energy. DOI: 10.7176/JEES/10-2-06 Publication date: February 29th 202

Effect of Bacillus Subtilis Bacteria on The Mechanical Properties of Corroded Self-Healing Concrete

Reinforced concrete has a weakness for corrosion which can cause the concrete to crack and the concrete structure to fail. To overcome this problem, a self-healing concrete method is needed that can close cracks and inhibit the rate of natural corrosion. Bacillus subtilis as a self-healing agent in concrete has been proven to be able to increase the compressive strength and flexural strength of concrete. The method used in this research is to add bacterial hydrogel encapsulation to concrete with a variation of 0%; 0.1%; 0.6%; and 1.5% by weight of sand. The test object is a reinforced concrete beams and cylindrical concrete with compressive design strength of 30 MPa. The concrete specimens will go through a series of tests, such as corrosion acceleration tests using DC power supply, self-healing tests by visual observation, flexural strength, ductility, stiffness, and compressive strength tests using Universal Testing Machine (UTM). From the test results, it was found that the addition of 0.1% bacterial encapsulation variation was the optimum value for increasing the mechanical properties of self-healing concrete and reduce the corrosion rate on self-healing concrete

Flexural Strength Behavior of Composite UHPFC-Existing Concrete

Article Preview Article Preview Ultra high performance fiber concrete (UHPFC) is an advanced formula concrete that is proven to be more superior than conventional concrete because it embrace the qualities of steel and concrete. Therefore UHPFC properties which include high durability and strength are fully exploited in the research of rehabilitation and strengthening in concrete and even non-concrete structures. This article presents the findings of an experimental study carried out to examine the bonding strength behaviour between normal concrete (NC) substrate and UHPFC as a repair material, under flexural strength test by using third-point loading beam test method. Three types of NC substrate surface preparation were used: as-cast (without surface preparation) as a reference, wire-brushed, and sand-blasted. The flexural test results clearly indicated that all failures occurred through the NC substrate and no

Performance of green high-strength concrete incorporating palm oil fuel ash in harsh environments

The corrosion of steel reinforcement by chloride is commonly recognized as a key factor that contributes to the degradation of durability in reinforced concreae structures. Using supplementary cementitious materials, such as industrial and agricultural waste materials, usually enhances the impermeability of the concrete and its corrosion resistance, acid resistance, and sulfate resistance. This study’s primary purpose is to examine the effects of replacing ordinary Portland cement (OPC) with ultrafine palm oil fuel ash (U-POFA) on the corrosion resistant performance of high-strength green concrete (HSGC). There were four HSGC mixes tested; the first mix contained 100% OPC, while the other mixes replaced OPC mass with 20%, 40%, and 60% of U-POFA. The performance of all HSGC mixes containing U-POFA on workability, compressive strength, porosity, water absorption, impressed voltage test, and mass loss was investigated at 7, 28, 60, and 90 days. Adding U-POFA to mixes enhances their workability, compressive strength (CS), water absorption, and porosity in comparison with mixes that contain 100% OPC. The findings clearly portrayed that the utilization of U-POFA as a partial alternative for OPC significantly enhances the corrosion-resistant performance of the HSGC. In general, it is strongly advised that a high proportion of U-POFA be incorporated, totaling 60% of the OPC content. This recommendation is the result of its significance as an environmentally friendly and cost-effective green pozzolanic material. Hence, it could contribute to the superior durability performance of concrete structures, particularly in aggressive environmental exposures. Highlights: The corrosion resistance performance of high-strength green concrete was investigated. Ultrafine palm oil fuel ash as a partial alternative of cement mass with 20%, 40%, and 60% was used. HSGC performance was evaluated in terms of workability, compressive strength, water absorption, porosity, impact stress testing, and mass loss

The Impact Of Oral Health Education And Preventive Measures On Dental Caries And Periodontal Diseases

Oral problems, including dental caries, periodontal diseases, and tooth loss, are significant global public health concerns. This is due to the fact that inadequate oral health has extensive impacts on general health and quality of life. In improving oral health, especially in developing countries, there are obstacles that need to be addressed. It is crucial to enhance public health programs worldwide by implementing efficient preventative measures against diseases and simultaneously boosting oral health. Frequently, collective actions are employed for the purpose of oral health education. These actions often involve delivering lectures utilizing various materials such as flipcharts, videos, PowerPoint presentations, as well as implementing other activities like supervised teeth brushing and topical fluoride application. This paper aimed to review the impact of oral health education and preventive measures on dental caries and periodontal diseases

Diabesity in the Arabian Gulf: Challenges and Opportunities

Diabesity (diabetes associated with obesity) is a major global and local public health concern, which has almost reached an epidemic order of magnitude in the countries of the Arabian Gulf and worldwide. We sought to review the lifestyle trends in this region and to highlight the challenges and opportunities that health care professionals face and attempt to address and correct them. In this regard, we aimed to review the regional data and widely held expert opinions in the Arabian Gulf and provide a thematic review of the size of the problem of diabesity and its risk factors, challenges, and opportunities. We also wished to delineate the barriers to health promotion, disease prevention, and identify social customs contributing to these challenges. Lastly, we wished to address specific problems with particular relevance to the region such as minimal exercise and unhealthy nutrition, concerns during pregnancy, the subject of childhood obesity, the impact of Ramadan fasting, and the expanding role of bariatric surgery. Finally, general recommendations for prevention, evidence-based, and culturally competent management strategies are presented to be considered at the levels of the individual, community, and policymakers

Impact of opioid-free analgesia on pain severity and patient satisfaction after discharge from surgery: multispecialty, prospective cohort study in 25 countries

Background: Balancing opioid stewardship and the need for adequate analgesia following discharge after surgery is challenging. This study aimed to compare the outcomes for patients discharged with opioid versus opioid-free analgesia after common surgical procedures.Methods: This international, multicentre, prospective cohort study collected data from patients undergoing common acute and elective general surgical, urological, gynaecological, and orthopaedic procedures. The primary outcomes were patient-reported time in severe pain measured on a numerical analogue scale from 0 to 100% and patient-reported satisfaction with pain relief during the first week following discharge. Data were collected by in-hospital chart review and patient telephone interview 1 week after discharge.Results: The study recruited 4273 patients from 144 centres in 25 countries; 1311 patients (30.7%) were prescribed opioid analgesia at discharge. Patients reported being in severe pain for 10 (i.q.r. 1-30)% of the first week after discharge and rated satisfaction with analgesia as 90 (i.q.r. 80-100) of 100. After adjustment for confounders, opioid analgesia on discharge was independently associated with increased pain severity (risk ratio 1.52, 95% c.i. 1.31 to 1.76; P < 0.001) and re-presentation to healthcare providers owing to side-effects of medication (OR 2.38, 95% c.i. 1.36 to 4.17; P = 0.004), but not with satisfaction with analgesia (beta coefficient 0.92, 95% c.i. -1.52 to 3.36; P = 0.468) compared with opioid-free analgesia. Although opioid prescribing varied greatly between high-income and low- and middle-income countries, patient-reported outcomes did not.Conclusion: Opioid analgesia prescription on surgical discharge is associated with a higher risk of re-presentation owing to side-effects of medication and increased patient-reported pain, but not with changes in patient-reported satisfaction. Opioid-free discharge analgesia should be adopted routinely

Effect of harsh environment on ‎cement mortar ‎containing natural pozzolans

This investigation aims to study the effect of the harsh environment on cement mortar containing pumice powder (natural pozzolana) as a partial substitute for ordinary Portland cement (OPC). The harsh environmental conditions applied in this study consisted of seawater supplemented with 5% of sodium sulfate (Na2SO4). Mortar mixtures were produced by replacing 0%, 5%, 10%, and 20% of the OPC mass with natural pozzolana (NP). Mortar samples were treated under two conditions. First, the mortar samples were immersed in tap water. Second, mortar samples are immersed in harsh environmental conditions. In the harsh environment, mortar samples were subjected to 90 cycles of dry-wet, 48-hour drying, and 48-hour wetting over a period of 360 days. Compressive strength, flexural strength, strength loss, change in length, water absorption, and initial surface absorption tests were performed on specimens aged 7, 28, 90, 180, and 360 days. Besides thermogravimetric and microstructure analysis of cement samples that were conducted at a test age of 180 days. The inclusion of NP as a partial replacement of OPC at a rate of 10% improved the results of compressive and flexural strength and achieved the lowest rates of porosity and water absorption of the mortar samples. The inclusion of NP as a partial replacement for OPC reduced the damage caused by the harsh environment

Effect of curing methods in hot weather on the properties of high-strength concretes

The properties of high-strength concrete (HSC) are significantly influenced by environmental conditions and the duration of the curing method. This paper presents an experimental study that investigated the influence of three types of curing methods during hot weather on the properties of hardened HSC reinforced with 0.0% or 0.22% (by volume fraction) polypropylene fibers (PFs). HSC samples were cured via water immersion under indoor laboratory conditions; wet-coverage with a wet gunny under outdoor conditions; and spraying with water twice day for one week under outdoor conditions. The concrete mixture was designed to achieve compressive strength beyond 60 MPa after 28 days of curing via water immersion. Various tests were conducted to determine HSC properties, including slump, compressive, indirect tensile and flexural strengths. Cubes, cylinders, and prisms were cast with each concrete mixture to measure strength at 7, 14, 28, and 90 days of curing. Compressive strength under all curing conditions with and without PF reinforcement exceeded 60 MPa at 28 days. PF-reinforced concrete cured via water immersion exhibited the best concrete strength. Keywords: Compressive strength, Curing methods, High strength concrete, Hot weather, Polypropylene fiber