Nahla Hilal

Bio: Nahla Hilal is an academic researcher from University of Fallujah. The author has contributed to research in topics: Compressive strength & Flexural strength. The author has an hindex of 8, co-authored 25 publications receiving 295 citations. Previous affiliations of Nahla Hilal include University of Anbar.

The possibility of enhancing some properties of self-compacting concrete by adding waste plastic fibers

Abstract: An attempt was carried out to develop some properties of self-compacted concrete (SCC) by adding waste plastic fibers (WPF) resulting from cutting beverage bottles. Many tests were conducted to investigate the effect of adding WPF on the fresh properties, whereas other tests were applied on that kind of concrete to study the effect of this type of waste on hardened properties. For this reason, different self-compacting concrete mixtures were designed at constant water-to-binder ratio of 0.35 and 490 kg/m3 of binder content. The class F fly ash was replaced with cement as 25% by weight. The eighth designated plastic fiber contents of 0%, 0.25%, 0.5%, 0.75%, 1%, 1.25%, 1.5%, 1.75% and 2% by volume. The workability properties of self-compacting concrete mixtures were performed to slump flow diameter, T50 slump flow simultaneously, V-funnel flow at the same time, and L-box height ratio. The 7, 14 and 28-day compressive strengths of self-compacting concretes were also measured. Moreover, the 7, 14 and 28-day flexural strengths of concretes were also measured. The test results showed that the plastic fibers have adverse effect on the fresh properties of self-compacting concrete and improvement by hardened properties.

Fresh properties of self-compacting concrete with plastic waste as partial replacement of sand

Abstract: This work aimed to investigate effecting of using plastic waste as partial replacement of fine aggregate, on the fresh characteristics of self-compacting concrete (SSC). For this purpose, different self-compacting concrete mixes were designed at constant water-to-binder ratio of 0.32 and 520 kg/m3 of binder content. Class F fly ash was used as partial replacement of cement (30% by weight of cement). The six designated plastic waste contents of 0, 2.5, 5, 7.5, 10, and 12.5% and three different sized Plastic wastes (fine plastic wastes, coarse plastic wastes, and mixed plastic waste) were considered as experimental parameters. The workability properties of self-compacting concrete mixtures were performed regarding to slump flow diameter, T50 slump flow time, V-funnel flow time, L-box height ratio, and L-box T20 and T40 flow times. The 28-day compressive strengths of self-compacting concretes were also measured. The experimental results of this work are showed that the plastic waste with the sizes and contents that used in this work can be used successfully as a fine aggregate in self-compacting concrete.

Use of recycled fibers in concrete composites: A systematic comprehensive review

Abstract: Municipal solid waste materials are growing worldwide due to human consumption. Nowadays, a different type of goods on large-scale is produced in the factories which is going to generate numerous amount of solid waste materials in the near future. Therefore, the management of these solid waste materials is a great concern around the world. Inadequate landfill, environmental pollution and its financial burden on relevant authorities, recycling and utilization of waste materials have a significant impact compared to disposing them. Studies have been done to reuse of waste materials as one of the elements of concrete composites. Each of the elements gives the concrete strength; however, the reuse of these wastes not only makes the concrete economical and sustainable, but also helps in decreasing environmental pollution. There are a number of different types of waste materials such as plastics, carpets, steels, tires, glass, and several types of ashes. In this paper, a comprehensive review was carried out on the influence of recycled plastic fibers (RPFs), recycled carpet fibers (RCFs) and recycled steel fibers (RSFs) on the fresh, mechanical and ductility properties of concrete. The previous studies were investigated to highlight the effects of these waste product fibers on the most important concrete properties such as slump, compressive strength, splitting tensile strength, flexural strength, modulus of elasticity, ultrasonic pulse velocity, energy absorption, ductility, and toughness. In this regard, more than 200 published papers were collected, and then the methods of preparation and properties of these recycled fibers (RF) were reviewed and analyzed. Moreover, empirical models using mechanical properties were also developed. As a result, RPFs, RCFs and RSFs could be used safely in concrete composites due to it is satisfactory fresh, physical and mechanical properties.

Hardened properties of self-compacting concrete with different crumb rubber size and content

Abstract: This paper aims at investigating the effect of crumb rubber size and content on hardened characteristics of self-compacting concrete. To this end, different self-compacting concrete mixtures were designed at constant water-to-binder ratio of 0.35 and 520 kg/m 3 of binder content. The class F fly ash was replaced with cement as 30% by weight. Six designated crumb rubber contents of 5%, 10%, 15%, 20%, and 25% and three different sized crumb rubbers (No. 18, No. 5, and mixed crumb rubber) were considered as experimental parameters. According to the obtained results, the use of crumb rubber had a negative effect on the hardened properties of self-compacting concretes and the significant improvement was achieved with addition of all tire wastes types, for ductility.

Properties of ultra-high-performance fiber-reinforced concrete (UHPFRC)—a review paper

Abstract: This study aims to review the research studies available in literature that examines the mechanical properties and optimum mixing ratios of ultra-high performance fiber-reinforced concretes (UHPFRCs). In addition to a comparison between mechanical properties of UHPFRC, high-performance concrete (HPC), and normal strength concrete (NSC). The studies included in this review were compiled under different headings and explained concisely. Subsequently, the best UHPFRC mixture was determined to be obtainable with 2% to 3% steel fiber content and a water/cement ratio of <0.2. Additionally, the UHPFRCs that were subjected to curing at 90 °C for 28 days yielded compressive, tensile, and flexural strengths that were 49% better than the samples cured at 20 °C. The review elucidates the key points of producing the best UHPFRC material for future applications.

American Society for Testing and Materials

Abstract: The American Society for Testing and Materials (ASTM) is an independent organization devoted to the development of standards.

Properties Of Concrete

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Environmental challenges induced by extensive use of face masks during COVID-19: A review and potential solutions

Abstract: The ongoing COVID-19 disease significantly affects not only human health, it also affects the wealth of country’ economy and everyday routine of human life. To control the spread of the virus, face mask is used as primary personal protective equipment (PPE). Thus, the production and usage of face masks significantly increase as the COVID-19 pandemic still escalating. Further, most of these masks contain plastics or other derivatives of plastics. Therefore, this extensive usage of face masks generates million tons of plastic wastes to the environments in a short span of time. This study aims to investigate the environmental impact induced by face mask wastes and sustainable solution to reduce this waste. An online survey was carried out to identify the types of face mask and number of masks used per week by an individual from 1033 people. Based on this survey and available literature, this study quantifies the amount of plastics waste generated by face masks. However, this survey was limited with certain ages, country and durations (July–August 2020). Thus, the prediction of plastic waste generation, only provide fundamental knowledge about the mask wastes. Results revealed that there is a huge plastic waste remained in land and marine environment in the form of mask waste, which will contribute to micro-plastic pollution. Therefore, this paper also highlights the sustainable approach to the mask production by integrating the use of natural plant fiber in the woven face mask technology to reduce the plastic waste induced by masks. Further, upcycling the mask waste and producing construction materials also discussed.