ORCID Profile
0000-0001-5529-3283
Current Organisation
University of South Australia
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Publisher: Springer Singapore
Date: 04-09-2020
Publisher: MDPI AG
Date: 15-06-2023
DOI: 10.3390/JCS7060250
Abstract: Basalt fiber (BF) is an environmentally friendly type of fiber that has attracted the attention of researchers in recent years due to its excellent performance in concrete constructions. This current research was conducted to investigate the effect of chopped basalt fiber on the workability, compressive strength, and impact resistance of high-performance concrete (HPC). Three various lengths (3, 12, and 18 mm) and six volume fractions (0%, 0.075%, 0.15%, 0.3%, 0.45%, and 0.6% by concrete volume) of BF were used in producing sixteen HPC mixes. HPC compressive strength and impact resistance were measured for each mix. Scanning electron microscopy (SEM) analysis was also conducted on selected mixes to closely investigate the effects of the applied variables through the microstructural scale. An empirical model was developed to study the relationship between the impact energy and compressive strength of BF-reinforced HPC. The results show that adding BF improves the compressive strength and impact resistance. Compared with the control concrete, the compressive strength of the HPC reinforced with 3 mm, 12 mm, and 18 mm BF increased by 12.2%, 15.1%, and 17.5%, respectively. The impact resistance increased with a dosage of 8 kg/m3 for all lengths of BF. The SEM observations revealed that the BF accumulated in pores and on the surface of the attached cement which improved the microstructure of the interfacial transition zone (ITZ), which further enhanced the strength and ductility of the HPC.
Publisher: Elsevier BV
Date: 10-2016
Publisher: Elsevier BV
Date: 02-2021
Publisher: MDPI AG
Date: 31-05-2023
DOI: 10.3390/BUILDINGS13061430
Abstract: In this study, fourteen sustainable concrete mixes containing metakaolin (MK) as supplementary cement material (SCM) and magnetized water (MW) as concrete mixing water were designed, prepared, tested, analyzed, and compared. The MK was used as a partial replacement of cement weight by 5%, 10%, and 20%, and as an additive to cement by 5%, 10%, and 20% of cement weight. The MW was used to fully replace tap water (TW) in concrete mixes and was prepared using two different magnetic fields of 1.4 tesla (T) and 1.6 T. This experimental research aimed to assess the characteristics of concrete manufactured with MK and MW. The mechanical and durability characteristics of fresh and hardened concrete were measured for the assessment. Microstructural and chemical analyses were carried out on selected materials and concrete mixes. The workability and compressive strength of the materials at 7, 28, and 365 days were measured, in addition to the splitting tensile strength at 28 days and the flexural strength at 28 days. The compressive strength at 365 days was conducted at 18 °C and 100 °C to study the effect of the applied variables on the concrete durability at different elevated temperatures. The microstructural and chemical analyses were conducted using a scanning electron microscope (SEM), energy dispersive X-ray (EDX), and Fourier transform infrared (FTIR) spectroscopy. The results showed that using 10% MK as a cement additive was the best ratio in this study, which enhanced all the measured mechanical characteristics when the TW or MW was used. Using MW instead of TW in MK concrete increased all the mechanical properties measured at 28 days by about 32–35%. The results of the microstructural and chemical analyses supported the compressive strength increase by showing indications of more C-S-H gel production and less CH when using MW in MK concrete. In addition, fewer micro-cracks and pores, and relatively denser concrete, were detected when using MW with 10% MK as a cement additive.
Publisher: MDPI AG
Date: 08-10-2023
DOI: 10.3390/SU151914570
Publisher: Wiley
Date: 05-2016
DOI: 10.1111/PAI.12563
Publisher: MDPI AG
Date: 25-12-2022
DOI: 10.3390/BUILDINGS13010044
Abstract: The aim of this study is to experimentally investigate the mechanical characteristics of concrete combining silica fume (SF) and magnetized water (MW). A total of nine concrete mixes were prepared and tested for workability, compressive strength, splitting tensile strength, and flexural strength. Ordinary tap water (TW) and MW that was prepared with five proposed different methods were utilized in the concrete mixes. The MW was prepared by passing TW through a permanent magnetic field (having intensities of 1.4 Tesla and/or 1.6 Tesla) for a different number of cycles, namely 100, 150, and 250 cycles. Water characteristics were analyzed after being magnetized using the proposed different methods and compared with the TW characteristics. Non-destructive concrete testing (ultrasonic pulse velocity, and Schmidt hammer) was also conducted to determine the effect of MW on the prediction of concrete compressive strength. Scanning electron microscopy (SEM) analysis and energy dispersive X-ray (EDX) analysis were carried out on the produced mixes. Regardless of the method utilized to prepare the MW, the results revealed a considerable improvement in concrete compressive strength, splitting tensile strength, and flexural strength by up to 80%, 98%, and 22%, respectively, when MW was prepared with 150 cycles. The best water magnetization method found in this study was the passing of water through magnetic fields of 1.6T then 1.4T intensities for 150 cycles. The ultrasonic pulse velocity test resulted in good prediction of the concrete compressive strength with overall error ranged between −12.6% and +5.8%. MW significantly improved the concrete microstructure and produced a denser structure in comparison to the control conventional concrete.
Publisher: MDPI AG
Date: 06-01-2020
Abstract: Improving the thermal insulation properties of cement-based materials is the key to reducing energy loss and consumption in buildings. Lightweight cement-based composites can be used efficiently for this purpose, as a structural material with load bearing ability or as a non-structural one for thermal insulation. In this research, lightweight cement pastes containing fly ash and cement were prepared and tested. In these mixes, three different techniques for producing air voids inside the cement paste were used through the incorporation of aluminum powder (AL), air entraining agent (AA), and hollow microspheres (AS). Several experiments were carried out in order to examine the structural and physical characteristics of the cement composites, including dry density, compressive strength, porosity and absorption. A Hot Disk device was used to evaluate the thermal conductivity of different cement composites. In addition, X-ray micro-computed tomography (micro-CT) was adopted to investigate the microstructure of the air-entrained cement pastes and the spatial distribution of the voids inside pastes without destroying the specimens. The experimental results obtained showed that AS specimens with admixture of hollow microspheres can improve the compressive strength of cement composites compared to other air entraining admixtures at the same density level. It was also confirmed that the incorporation of aluminum powder creates large voids, which have a negative effect on specimens’ strength and absorption.
Publisher: Springer Science and Business Media LLC
Date: 29-07-2016
Publisher: Unpublished
Date: 2013
Publisher: Elsevier BV
Date: 06-2018
Publisher: Wiley
Date: 02-02-2015
DOI: 10.1111/ALL.12563
Publisher: Frontiers Media SA
Date: 19-11-2019
Publisher: Public Library of Science (PLoS)
Date: 29-05-2014
Publisher: Elsevier BV
Date: 04-2016
Publisher: SAGE Publications
Date: 2021
DOI: 10.1177/21526567211010728
Abstract: The most severe thunderstorm asthma (TA) event occurred in Melbourne on the 21st November 2016 and during this period, daily pollen information was available and accessible on smart devices via an App. An integrated survey within the App allows users to self-report symptoms. To explore patterns of symptom survey results during the period when the TA event occurred. Symptom data from the Melbourne Pollen Count and Forecast App related to asthma history, hay fever symptoms, and medication use was explored. A one-week control period before and after the event was considered. Chi-square tests and logistic regression were used to assess associations between sex, age, symptoms, and medication use. Of the 28,655 responses, during the 2016 pollen season, younger (18 to 40 years) males, with no hay fever and no asthma were the most single and regular responders. During the TA event for new users, sex was only significantly associated with hay fever ( p = 0.008) of which 60.2% of females’ responses reported having hay fever, while 43% of males’ responses did not. Those with mild symptoms peaked during the TA event. Many in iduals completed the survey on the app for the first time during the TA event indicating the potential of digital technologies to be used as indicators of health risk among populations at risk of TA events.
Publisher: Elsevier BV
Date: 07-2020
Publisher: Cold Spring Harbor Laboratory
Date: 21-12-2019
DOI: 10.1101/2019.12.20.885343
Abstract: Pathological activation and collaboration of T and B cells underlies pathogenic autoantibody responses. Existing treatments for autoimmune disease cause non-specific immunosuppression and induction of antigen-specific tolerance remains an elusive goal. Many immunotherapies aim to manipulate the T-cell component of T-B interplay but few directly target B cells. One possible means to specifically target B cells is the transfer of gene-engineered BM that, once engrafted, gives rise to widespread specific and tolerogenic antigen expression within the hematopoietic system. Gene-engineered bone marrow encoding ubiquitous ovalbumin expression was transferred after low-dose (300cGy) immune-preserving irradiation. B-cell responsiveness was monitored by analyzing ovalbumin-specific antibody production after immunization with ovalbumin/complete Freund’s adjuvant. Ovalbumin-specific B cells and their response to immunization were analyzed using multi-tetramer staining. When antigen-encoding bone marrow was transferred under immune-preserving conditions, cognate antigen-specific B cells were purged from the recipient’s pre-existing B cell repertoire as well as the repertoire that arose after bone marrow transfer. OVA-specific B-cell deletion was apparent within the established host B-cell repertoire as well as that developing after gene-engineered bone marrow transfer. OVA-specific antibody production was substantially inhibited by transfer of OVA-encoding BM and activation of OVA-specific B cells, germinal centre formation and subsequent OVA-specific plasmablast differentiation were all inhibited. Low levels of gene-engineered bone marrow chimerism were sufficient to limit antigen-specific antibody production. These data show that antigen-specific B cells within an established B-cell repertoire are susceptible to de novo tolerance induction and this can be achieved by transfer of gene-engineered bone marrow. This adds further dimensions to the utility of antigen-encoding bone marrow transfer as an immunotherapeutic tool.
Publisher: Elsevier BV
Date: 02-2015
Publisher: Elsevier BV
Date: 05-2017
Publisher: Elsevier BV
Date: 04-2022
Publisher: MDPI AG
Date: 19-06-2019
DOI: 10.3390/JCS3020062
Abstract: Double-skin tubular columns (DSTCs) have become a competitive candidate for column members due to their important advantages compared with conventional reinforced concrete columns, including their better weight-to-strength ratio and ease of construction. Using Rubcrete in hybrid DSTCs is of great interest due to the potential of this system to overcome the Rubcrete material deficiencies and to add more ductility, toughness, seismic resistance, confinement effectiveness, and environmentally-friendly features to that structural system compared to conventional concrete. In this paper, hybrid DSTCs made out of Rubcrete, sandwiched between a fibre reinforced polymer (FRP) tube and a steel tube, were tested. The examined variables were concrete sand or stone replacement ratio (0% and 20%), FRP wall thickness (1- and 2-layers), steel wall thickness (3.2 mm and 4.5 mm), void ratio (50% and 76%), and void shape (circular or square). The axial and lateral stress–strain responses were monitored, measured, and compared. According to this investigation, using Rubcrete in hybrid DSTCs can enhance the axial and hoop strain capacities, especially with fine rubber particles. It was also observed that the adverse influence of using rubber on column ultimate capacity was much lower in DSTC specimens, compared with that of unconfined Rubcrete columns. Therefore, using Rubcrete with fine rubber particles is recommended in DSTC structural columns.
Publisher: S. Karger AG
Date: 2014
DOI: 10.1159/000369341
Abstract: b i Background: /i /b Pollens of the Panicoideae subfamily of grasses including Bahia i (Paspalum notatum) /i are important allergen sources in subtropical regions of the world. An assay for specific IgE to the major molecular allergenic component, Pas n 1, of Bahia grass pollen (BaGP) would have immunodiagnostic utility for patients with pollen allergy in these regions. b i Methods: /i /b Biotinylated Pas n 1 purified from BaGP was coated onto streptavidin ImmunoCAPs. Subjects were assessed by clinical history of allergic rhinitis and skin prick test (SPT) to aeroallergens. Serum total, BaGP-specific and Pas n 1-specific IgE were measured. b i Results: /i /b Pas n 1 IgE concentrations were highly correlated with BaGP SPT (r = 0.795, p 0.0001) and BaGP IgE (r = 0.915, p 0.0001). At 0.23 kU/l Pas n 1 IgE, the diagnostic sensitivity (92.4%) and specificity (93.1%) for the detection of BaGP allergy was high (area under receiver operator curve 0.960, p 0.0001). The median concentrations of Pas n 1 IgE in non-atopic subjects (0.01 kU/l, n = 67) and those with other allergies (0.02 kU/l, n = 59) showed no inter-group difference, whilst grass pollen-allergic patients with allergic rhinitis showed elevated Pas n 1 IgE (6.71 kU/l, n = 182, p 0.0001). The inter-assay coefficient of variation for the BaGP-allergic serum pool was 6.92%. b i Conclusions: /i /b Pas n 1 IgE appears to account for most of the BaGP-specific IgE. This molecular component immunoassay for Pas n 1 IgE has potential utility to improve the sensitivity and accuracy of diagnosis of BaGP allergy for patients in subtropical regions.
Publisher: MDPI AG
Date: 08-02-2023
DOI: 10.3390/MA16041412
Abstract: This study reports a potential approach for the valorization of glass waste (GW) that is mainly composed of amorphous silica to prepare lightweight foamed glass (FG). The preparation of FG was achieved by mixing sodium hydroxide with GW powder followed by sintering at a temperature of 800 °C. As-synthesized FG was characterized and applied as an effective adsorbent for the removal of hazardous organic water contaminants, in particular, methylene blue (MB) dye. FG exhibited porosity of 91%, bulk density of 0.65 g/cm3, compressive strength of 4 MPa, and thermal conductivity of 0.27 W/m·K. Theoretical treatment indicated that a monolayer model with one energy site was the best in fitting the removal of MB molecules. The number of MB molecules per active site (n) ranged from 2.20 to 1.70, suggesting vertical orientation and a multi-molecular adsorption mechanism. The density of FG receptor sites (DM) increased with the temperature, and this parameter played a vital role in the adsorption process. The adsorption capacity (Qsat) increased from 255.11 to 305.58 mg/g, which signifies endothermic interactions. MB adsorption on FG was controlled by physical forces such as electrostatic interactions (i.e., the adsorption energies were kJ/mol). The results of this study prove the feasibility of glass waste as an effective and low-cost adsorbent for water remediation.
Publisher: Elsevier BV
Date: 12-2019
Publisher: Elsevier BV
Date: 05-2019
Publisher: Springer Science and Business Media LLC
Date: 17-11-2018
Publisher: Elsevier BV
Date: 10-2017
Publisher: Elsevier BV
Date: 10-2015
Publisher: Elsevier BV
Date: 02-2021
Publisher: MDPI AG
Date: 09-01-2021
Abstract: Adolescent asthma is still a major problem with poor adherence to treatment. Globally, adolescents are devoted users of smartphone technologies and app use in asthma self-management may improve adherence. The objective of this systematic review is to assess the feasibility and efficacy of mobile technology in improving asthma outcomes in adolescents. We conducted an extensive review of the peer-review literature of studies with populations consisting of children and adolescents under 18 years in seven bibliographic databases and Google Scholar. All study designs were considered. Quality assessment of included studies were independently assessed and reported. The search identified 291 articles of the 16 eligible full-text papers, 8 met the review criteria, reporting two interventional, two qualitative and four observational studies. S les ranged from 12 to 21 participants. Heterogeneity related to study design and the methods of the included studies prevented meta-analysis. Nevertheless, the intervention studies reported a positive effect of smartphone apps on asthma control, medication adherence and self-efficacy. Smartphone apps may be an effective asthma control tool especially among adolescents who are major users of smartphones however, conclusions are limited by a lack of controlled trials and adequate s le sizes.
Publisher: Elsevier BV
Date: 05-2020
Publisher: Elsevier BV
Date: 10-2015
Publisher: Elsevier BV
Date: 11-2014
Publisher: MDPI AG
Date: 26-05-2021
DOI: 10.3390/JCS5060143
Abstract: There is a lot of ongoing active research all over the world looking for various applications of used tyre rubber, to increase its utilisation rate. One of the common research applications is to incorporate rubber into concrete as a partial replacement for conventional aggregates. However, due to its poor bonding performance with cement paste, the utilisation of rubber in concrete has been hindered to date. A cost-effective and time-saving rubber pre-treatment method is of great interest, especially for the concrete industry. Out of all the various pre-treatment methods, soaking rubber particles in water is the most cost-effective and least complex method. In addition, sodium sulphate accelerates the hydration reaction of the cement composites. This study looks at the effect of soaking crumb rubber in tap water for short (2 h) and long (24 h) durations, and the optimised duration was then compared with soaking the crumb rubber in a 5% concentration of sodium sulphate solution. Compressive strength, bond behaviour, and rubber/cement interfacial transition zone (ITZ) were investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis. The results demonstrate that a soaking duration of 2 h provides much better performance in both the strength and bond properties compared to 24-h soaking. A further improvement in the 7-day strength was achieved with the rubber soaked in 5% sodium sulphate solution for 2 h, providing a more practical and economical rubber pre-treatment method for concrete industry use.
Publisher: Elsevier BV
Date: 05-2021
Publisher: Elsevier BV
Date: 06-2018
Publisher: Elsevier BV
Date: 2015
Publisher: Elsevier BV
Date: 11-2015
Publisher: Elsevier BV
Date: 08-2015
Publisher: Wiley
Date: 15-05-2021
Abstract: Patient characteristics with exacerbation of asthma accessing care in the ED who are at risk of hospital admission have not been determined in subtropical climates. The objective of the study was to investigate the spatiotemporal burden of asthma hospital admissions across Queensland (QLD) and model risk factors for asthma hospital admission following an ED visit. Six years of routinely collected data (2012–2017) from 28 QLD public hospitals were extracted from Queensland Health's Emergency Data Collection. The dataset contained in idual, episode‐level ED presentations having asthma‐like diagnoses, and an indicator of hospital admission, including to short‐stay unit (SSU). A generalised additive model was used to examine the risk of asthma hospital admission. Asthma hospital admissions increased from a weekly median of 79 (interquartile range [IQR] 66–99) in 2012 to 104 (IQR 81–135) in 2017. A higher incidence of asthma hospital admission was observed among males (median age 9, IQR 5–32) in childhood and females in adulthood (median age 32, IQR 11–51). Compared to the state capital Brisbane, the odds of asthma hospital admission ranged from 0.48 (95% CI 0.42–0.54) to 1.34 (95%CI 1.21–1.48) in other regions of QLD. Asthma hospital admissions appear to be increasing in QLD, largely driven by utilisation of the SSU admissions for asthma. With large variation in both incidence and proportion admitted across different regions, routinely collected data can in part be used to understand risk factors for asthma‐related hospital admission following an ED presentation and further inform public health policy development.
Publisher: OMICS Publishing Group
Date: 2012
Publisher: Elsevier BV
Date: 2022
Publisher: Wiley
Date: 17-04-2018
Publisher: Informa UK Limited
Date: 02-10-2020
Publisher: Wiley
Date: 02-03-2018
DOI: 10.1111/ALL.13407
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 2020
Publisher: Elsevier BV
Date: 12-2021
Publisher: MDPI AG
Date: 19-10-2022
DOI: 10.3390/JCS6100320
Abstract: Volcanic concrete is an eco-friendly concrete type in that it contains coarse and fine aggregates that all extracted from the igneous volcanic rock. However, utilizing of volcanic ash (VA) as partial/full replacement of concrete cement significantly affects the concrete workability, especially at high cement replacement ratios. This has also some adverse effects on concrete strength. Utilizing magnetized water (MW) in concrete as a partial/full replacement of ordinary tap water (TW) has a notable effect on enhancing the fresh and hardened concrete properties. This research aims to study the effect of using MW prepared in a magnetic field of 1.4 Tesla on the workability and hardened properties (compressive, tensile, and flexural strengths) of volcanic concrete. In this study, VA partially replaced volcanic concrete cement with ratios of 5%, 10%, 15%, and 20%. Ten volcanic concrete mixes were prepared in two groups. The first one was prepared with VA (0–20%) and mixed with TW. The other group was prepared with the same VA contents like group one, but mixed with MW. Microstructure imaging for volcanic concrete was also conducted in this study. Results of water tests showed 17% and 15% increase in total dissolved solids (TDS) and pH, respectively, of MW compared with those of TW. In addition, the water magnetization decreased the water surface tension by 7% compared with that of TW. Results of hardened concrete tests showed that the best ratio of VA in volcanic concrete was 5% with and without using magnetized water. The volcanic concrete slump decreased when using TW however, using MW enhanced the volcanic concrete slump by up to 8%. The compressive strength was improved by 35%, 23%, and 20% at 7 days, 28 days, and 120 days, respectively, with no VA and with the presence of MW. The compressive strength was improved by 11%, 12%, and 11% after 7 days, 28 days, and 120 days, respectively, with using 5% VA and with the presence of MW. Both splitting tensile strength and flexural strength of volcanic concrete with and without VA or MW behaved similar to that of the corresponding compressive strength.
Publisher: Elsevier BV
Date: 03-2020
Publisher: Elsevier BV
Date: 09-2017
Publisher: MDPI AG
Date: 07-01-2019
DOI: 10.3390/JCS3010005
Abstract: Due to the structural and economic features of steel–concrete–steel (SCS) structural systems compared with conventional reinforced concrete ones, they are now used for a range of structural applications. Rubcrete, in which crumbed rubber from scrap tires partially replaces mineral aggregates in concrete, can be used instead of conventional concrete. Utilizing rubber waste in concrete potentially results in a more ductile lightweight concrete that can introduce additional features to the SCS structural members. This study aimed to explore different concrete core materials in SCS beams and the appropriate shear connectors required. In this study, four SCS sandwich beams were tested experimentally under incrementally increasing flexure cyclic loading. Each beam had a length of 1000 mm, and upper and lower steel plates with 3 mm thickness sandwiched the concrete core, which had a cross-section of 150 mm × 150 mm. Two of the beams were constructed out of Rubcrete core with welded and bolted shear connectors, while the other two beams were constructed with welded shear connectors and either conventional concrete or lightweight expanded clay aggregate (LECA) concrete cores. The performance of the SCS sandwich beams including damage pattern, failure mode, load-displacement response, and energy dissipation behavior was compared. The results showed that, while Rubcrete was able to provide similar concrete cracking behavior and strength to that of conventional concrete, LECA concrete degraded the strength properties of SCS. Using bolted shear connectors instead of welded ones caused a high number of cracks that resulted in a reduced ductility and deflection capacity of the beam before failure. The rubberized concrete specimen presented an improved ductility and deflection capacity compared with its conventional concrete counterpart.
Publisher: Springer Science and Business Media LLC
Date: 09-2017
Publisher: Springer Science and Business Media LLC
Date: 11-10-2018
Publisher: Elsevier BV
Date: 12-2020
Publisher: BMJ
Date: 06-02-2018
DOI: 10.1136/BMJ.K432
Publisher: Elsevier BV
Date: 02-2014
Publisher: American Society of Civil Engineers (ASCE)
Date: 08-2017
Publisher: American Meteorological Society
Date: 02-2020
Abstract: In November 2016, an unprecedented epidemic thunderstorm asthma event in Victoria, Australia, resulted in many thousands of people developing breathing difficulties in a very short period of time, including 10 deaths, and created extreme demand across the Victorian health services. To better prepare for future events, a pilot forecasting system for epidemic thunderstorm asthma (ETSA) risk has been developed for Victoria. The system uses a categorical risk-based approach, combining operational forecasting of gusty winds in severe thunderstorms with statistical forecasts of high ambient grass pollen concentrations, which together generate the risk of epidemic thunderstorm asthma. This pilot system provides the first routine daily epidemic thunderstorm asthma risk forecasting service in the world that covers a wide area, and integrates into the health, ambulance, and emergency management sector. Epidemic thunderstorm asthma events have historically occurred infrequently, and no event of similar magnitude has impacted the Victorian health system since. However, during the first three years of the pilot, 2017–19, two high asthma presentation events and four moderate asthma presentation events were identified from public hospital emergency department records. The ETSA risk forecasts showed skill in discriminating between days with and without health impacts. However, even with hindsight of the actual weather and airborne grass pollen conditions, some high asthma presentation events occurred in districts that were assessed as low risk for ETSA, reflecting the challenge of predicting this unusual phenomenon.
Publisher: MDPI AG
Date: 02-10-2022
DOI: 10.3390/JCS6100290
Abstract: To eliminate the unfavorable effect of the accumulation of end-of-life car tires on the environment, many studies have been conducted to recycle those tires in concrete as a partial or full replacement of its natural aggregates. However, the produced rubberized concrete suffers from low compressive strength due to low adhesion at the rubber/cement interface. Pre-treating of rubber surfaces before use in concrete is the most effective way to overcome this adverse effect on the concrete strength. Several studies introduced different methods to enhance rubberized-concrete strength through pre-treating rubber particles, especially when using a high content of rubber in concrete. This study presents the results of experimental work on the effect of heat treatment on crumb-rubber–concrete mechanical performance. Rubber contents of 40%, 60% and 80% of sand volume were the variables in this study. Workability, density, compressive strength, and impact resistance were the measurements in this experimental work. The results showed that using saturated-surface dry (SSD) rubber can eliminate the adverse effect on concrete slump when using a high rubber volume or the heat-treated rubber. Using heat-treated rubber at 200 °C for 2 h as 40%, 60%, and 80% displayed compressive strength recoveries of 14.9%, 10.4% and 9.7%, respectively. Heat treatment of 40%, 60%, and 80% rubber contents increased the impact resistance for ultimate failure by 57%, 28%, and 7%, respectively, compared with those of the control mix. The thermal treatment enhanced the impact resistance at ultimate failure by 37%, 28%, and 15%, respectively, for mixes containing 40%, 60%, and 80% rubber contents compared with those of as-received rubber.
Publisher: MDPI AG
Date: 16-09-2021
DOI: 10.3390/MA14185353
Abstract: Experimental work was carried out to study new fine aggregate shielding construction materials, namely black sand (BS). The BS effect on the mechanical, durability, and shielding characteristics of heavyweight high-performance concrete (HWHPC) was evaluated. This study aimed at improving various HWHPC properties, concertedly. Fifteen mixtures of HWHPC were made, with various variables, including replacing 10% and 15% of the cement with fly ash (FA) and replacing normal sand by BS at various contents (15%, 30%, 45%, 60%, 75%, and 100%). The test specimens were subjected to various exposure conditions, including elevated temperatures, which ranged from 250 °C to 750 °C, for a duration of 3 h magnesium sulfate (MS) exposure and gamma-ray exposure. The effects of elevated temperature and sulfate resistance on concrete mass loss were examined. The results revealed that BS is a promising shielding construction material. The BS content is the most important factor influencing concrete compressive strength. Mixes containing 15% BS demonstrated significantly better strength compared to the control mixes. Exposure to 250 °C led to a notable increase in compressive strength. BS showed a significant effect on HWHPC fire resistance properties, especially at 750 °C and a significant linear attenuation coefficient. Using 10% FA with 15% BS was the most effective mixing proportion for improving all HWHPC properties concertedly, especially at greater ages.
Publisher: Elsevier BV
Date: 06-2020
Publisher: American Society of Civil Engineers (ASCE)
Date: 08-2020
Publisher: MDPI AG
Date: 10-04-2019
DOI: 10.3390/JCS3020041
Abstract: This research extensively investigates how to enhance the mechanical performance of Rubcrete, aiming to move this type of concrete from the laboratory research level to a more practical use by the concrete industry. The effects of many different mixing procedures, chemical pre-treatments on the rubber particles, and the use of fibre additives, have been investigated for their impact upon Rubcrete workability, compressive strength, tensile strength, and flexural strength. The mixing procedure variables included mixing time and mixing order. The rubber pre-treatments utilized chemicals such as Sodium Hydroxide (NaOH), Hydrogen Peroxide (H2O2), Sulphuric acid (H2SO4), Calcium Chloride (CaCl2), Potassium Permanganate (KMnO4), Sodium Bisulphite (NaHsO3), and Silane Coupling Agent. Soaking rubber particles in tap water, or running them through water before mixing, were also tried as a pre-treatment of rubber particles. In addition, the effects of fibre additives such as steel fibres, polypropylene fibres, and rubber fibres, were assessed. X-ray photoelectron spectroscopy (XPS) analysis was utilised to examine some of the pre-treated rubber particles. The results showed that doubling the net mixing time of all mix constituents together enhanced the Rubcrete slump by an average of 22%, and the compressive strength by up to 8%. Mixing rubber with dry cement before adding to the mix increased the compressive strength by up to 3%. Pre-treatment using water was more effective than other chemicals in enhancing the Rubcrete workability. Regardless of the treatment material type, the longer the time of the treatment, the more cleaning of rubber occurred. Significant Rubcrete flexural strength increase occurred when using 1.5% fibre content of both steel fibre and polypropylene fibre.
Publisher: Elsevier BV
Date: 11-2020
Publisher: Public Library of Science (PLoS)
Date: 25-02-2014
Publisher: Springer Singapore
Date: 04-09-2020
Publisher: Elsevier BV
Date: 08-2020
Publisher: Elsevier BV
Date: 08-2018
Publisher: Wiley
Date: 28-11-2016
DOI: 10.1111/CEA.12847
Publisher: Elsevier BV
Date: 02-2022
Publisher: Elsevier BV
Date: 08-2021
Publisher: Springer Science and Business Media LLC
Date: 05-04-2019
Publisher: Elsevier BV
Date: 04-2011
Publisher: S. Karger AG
Date: 2012
DOI: 10.1159/000338290
Abstract: b i Background: /i /b Bahia grass pollen (BaGP) is a major cause of allergic rhinitis. Subcutaneous allergen-specific immunotherapy is effective for grass pollen allergy, but is unsuitable for patients with moderate to severe asthma due to the risk of anaphylaxis. T cell-reactive but IgE nonreactive peptides provide a safer treatment option. This study aimed to identify and characterize dominant CD4 sup + /sup T cell epitope peptides of the major BaGP allergen, Pas n 1. b i Methods: /i /b Pas n 1-specific T cell lines generated from the peripheral blood of BaGP-allergic subjects were tested for proliferative and cytokine response to overlapping 20-mer Pas n 1 peptides. Cross-reactivity to homologous peptides from Lol p 1 and Cyn d 1 of Ryegrass and Bermuda grass pollen, respectively, was assessed using Pas n 1 peptide-specific T cell clones. MHC class II restriction of Pas n 1 peptide T cell recognition was determined by HLA blocking assays and peptide IgE reactivity tested by dot blotting. b i Results: /i /b Three Pas n 1 peptides showed dominant T cell reactivity 15 of 18 (83%) patients responded to one or more of these peptides. T cell clones specific for dominant Pas n 1 peptides showed evidence of species-specific T cell reactivity as well as cross-reactivity with other group 1 grass pollen allergens. The dominant Pas n 1 T cell epitope peptides showed HLA binding ersity and were non-IgE reactive. b i Conclusions: /i /b The immunodominant T cell-reactive Pas n 1 peptides are candidates for safe immunotherapy for in iduals, including those with asthma, who are allergic to Bahia and possibly other grass pollens.
Publisher: Elsevier BV
Date: 03-2017
Publisher: MDPI AG
Date: 27-12-2022
DOI: 10.3390/MA16010240
Abstract: Concrete sulfate attack is of great interest as it represents one of the main reasons of concrete deterioration and poor durability for concrete structures. In this research, the effect of different cement types on concrete sulfate resistance was investigated. This included three concrete classes, namely, low strength concrete, medium strength concrete, and high strength concrete. Blast furnace cement (BFC), sulfate resisting Portland cement (CEM I-SR5), and ordinary Portland cement (OPC) were used in a total of eighteen concrete mixes. Three binder contents of 250 kg/m3, 350 kg/m3, and 450 kg/m3 and a constant silica fume (SF) content were applied in this experimental study. The water/binder (w/b) ratio was varied between 0.4 and 0.8. Concrete specimens were immersed in highly severe effective sodium sulfate solutions (10,000 ppm) for 180 days after standard curing for 28 days. The fresh concrete performance was evaluated through a slump test to attain proper workability. Concrete compressive strength and mass change at 28 days and 180 days were measured before and after immersion in the solution to evaluate the long-term effect of sulfate attack on the proposed concrete durability. Scanning electron microscopy (SEM) analysis was conducted to study the concrete microstructure and its deterioration stages. The obtained results revealed that BFC cement has the best resistance to aggressive sulfate attacks. The strength deterioration of BFC cement was 3.5% with w/b of 0.4 and it increased to about 7.8% when increasing the w/b ratio to 0.6, which are comparable to other types of cement used. The findings of this research confirmed that the quality of concrete, specifically its composition of low permeability, is the best and recommended protection against sulfate attack.
Publisher: Informa UK Limited
Date: 12-2014
DOI: 10.2147/COPD.S53590
Publisher: MDPI AG
Date: 29-12-2022
Abstract: Limited information and data are available on the material and structural performance of GC incorporating lightweight fine aggregate. In this research, three types of lightweight fine materials were utilized to partially replace sand volume of GC. These lightweight materials were rubber, vermiculite, or lightweight expanded clay aggregate (LECA) and they were used in contents of 20%, 40%, 60%, and 100%. The variables were applied to better investigate the efficiency of each lightweight material in GC and to recommend GC mixes for structural applications. The concrete workability, compressive strength, indirect tensile strength, freezing and thawing performance, and impact resistance were measured in this study. In addition, three reinforced concrete slabs were made from selected mixes with similar compressive strength of 32 MPa and then tested under a 4-point bending loading regime. The results showed that using LECA as sand replacement in GC increased its compressive strength at all ages and all replacement ratios. Compared with the control GC mix, using 60% LECA increased the compressive strength by up to 44%, 39%, and 27%, respectively at 3, 7, and 28 days. The slabs test showed that partial or full replacement of GC sand adversely affected the shear resistance of concrete and caused premature failure of slabs. The slab strength and deflection capacities decreased by 9% and 30%, respectively when using rubber, and by 23% and 59%, respectively when using LECA, compared with control GC slab. The results indicated the applicability of GC mix with 60% LECA in structures subjected to axial loads. However, rubber would be the best lightweight material to recommend for resisting impact and flexural loads.
Publisher: MDPI AG
Date: 25-06-2023
DOI: 10.3390/SU151310060
Abstract: Worldwide, vast amounts of waste are produced every year and most waste is sent directly to landfills or burnt, which has severe and harmful impacts on the environment. Recycling waste materials is considered the most visible solution to protect the environment. Using scraps in concrete production is a proper method for getting rid of wastes, improving the characteristics of concrete, reducing the consumption of natural aggregates, and can be used as cementitious materials that decrease cement production so that the CO2 that is produced during cement manufacturing decreases. This review paper summarizes the use of recycled waste materials, including rubber tires, crushed glass, and crushed clay brick in concrete, as a fractional replacement of aggregates, cement, etc., to develop eco-friendly lightweight construction materials. It has been concluded that the dry density of sustainable concrete decreased to 4, 21.7, and 31.7% when crushed glass, clay brick, and rubber tire were incorporated into the concrete instead of traditional aggregate, respectively. Waste rubber has good results in sulfate, thermal, and impact resistance, while glass powder and finely crushed clay brick helped to improve mechanical properties by increasing reach by 33% for glass and a slight increase for crushed clay brick, as well as thermal resistance compared to normal concrete. Moreover, due to the low particle density of these waste materials compared to that of normal-weight aggregates, these materials can be utilized efficiently to produce lightweight concrete for structural and non-structural applications such as road engineering, flooring for mounting machinery, highway and rail crash barriers, permeable pavement, interlocking bricks, insulation, filling concrete, and bearing walls.
Publisher: Wiley
Date: 2020
DOI: 10.1002/CTI2.1103
Publisher: Elsevier BV
Date: 11-2015
Publisher: Elsevier BV
Date: 08-2018
Publisher: Elsevier BV
Date: 11-2018
Publisher: Springer Science and Business Media LLC
Date: 18-07-2019
Publisher: Elsevier BV
Date: 05-2018
No related grants have been discovered for Osama Youssf.