Finite element analysis of rectangular reinforced concrete columns wrapped with FRP composites

Fibre reinforced polymer (FRP) wrapping of reinforced concrete (RC) columns has increasingly become the most suitable method used to strengthen and rehabilitate RC columns. It is clear that limited studies have investigated the behaviour of eccentrically loaded RC columns wrapped with FRP composites. In the present study, a three-dimensional finite element (FE) model was developed to simulate the behaviour of rectangular RC columns wrapped with glass fibre-reinforced polymer (GFRP) sheets under concentric and eccentric loading. The FE model was developed in the finite element analysis software ANSYS. The variables within the FE model are the number of GFRP layers and the magnitude of load eccentricity. The FE analysis results showed that GFRP wrapping significantly improved the performance of the strengthened columns by delaying concrete rupture. The presence of load eccentricity reduced the load carrying capacity and performance of the strengthened RC columns. The FE model correlated well with the stress distribution trends observed in the literature

Life cycle assessment of geopolymer concrete: A Malaysian context

An electrochemical fuel cell contains first and second monolithic electrically conducting flow field-bipolar plate assemblies arranged essentially parallel to each other such that an inside surface of the first bipolar separator plate is facing an inside surface of the second bipolar separator plate, wherein the bipolar separator plates are electrically and mechanically connected by intervening layers that are directly bonded to each other. The fuel cells can be stacked between endplates and supplied with hydrogen and oxygen to generate electric power. An air cooled condenser for use with a fuel cell stack is composed of a porous foam condensing element and a porous foam cooling element. The condenser can be placed by a fuel cell stack for cooling purposes.U

Effect of Non-Traditional Supplementary Cementitious Materials in Concrete

Fly ash, silica fume, metakaolin and ground granulated blast furnace slag, etc. have been established as traditional supplementary cementitious materials (SCM) and cement replacement materials; however, other alternate materials such as palm oil fuel ash (POFA), palm oil clinker powder (POCP), eco-processed pozzolan (EPP) and rice husk ash (RHA) have emerged as non-traditional materials that would take a role in replacing some of those established SCM. With a closure of most of the coal-operated power plants and imminent closure of more plants, the search for alternate materials is on the rise. Thus, it is mandatory for the researchers and cement manufacturers to invest more time and efforts to apply sustainable development goals (SDG) on the replacement of virgin materials to achieve low-carbon materials. The suitability and the effect of the above-mentioned non-traditional materials are detailed and discussed. The oxide composition, particle size and shapes through multiple tests and investigations are outlined. The plentiful availability of such non-traditional materials not only paves way for more research interest, but a genuine means of execution of plans to vigorously utilize those materials. The concrete quality on using such materials such as pore refinement, creation of additional C–S–H and dilution effects has been discussed

Impact of Polyester Recron 3s Fiber on Fly Ash-based Portland Pozzolana Cement Mortars at Various Total Dissolved Solids Levels

This research investigates the effect of total dissolved solids (TDS) concentration on the properties of cement mortar, including setting time, flowability, compressive strength, water absorption, and permeability, with a constant addition of 0.5% Recron fiber. TDS levels were categorized as <500 ppm, 500–1500 ppm, 1500–2500 ppm, and >2500 ppm to reflect different water qualities. Results highlight the significant role of chloride ions in TDS, accelerating cement hydration and reducing setting time, particularly at 1500–2500 ppm. However, excessive TDS (>2500 ppm) causes flocculation, slightly delaying the setting process. Moderate TDS levels (500–1500 ppm) improved early compressive strength by filling cement pores, but strength declined beyond this range. Flowability remained consistent across all samples (105–115% flow), regardless of fiber inclusion or water quality variations. Higher TDS levels slightly reduced water absorption due to pore filling, while improving impermeability. A minor increase in permeability at elevated TDS concentrations suggests complex interactions affecting mortar durability. Additionally, Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) analysis revealed changes in silicate structures influencing durability. This research is novel in simultaneously investigating TDS concentration and fiber reinforcement, offering practical recommendations for coastal construction

Evaluation of the effect of fineness of fly ash in type I and type II Portland cement blended mortars

This study evaluates the effects of fineness-modified Class F fly ash (FA) on the performance of Type I and Type II Ordinary Portland Cement (OPC) mortars. FA was mechanically ground to achieve 90% (GFA1) and 98% (GFA2) passing through a 45-µm sieve, replacing OPC at 10%, 30%, and 50% by weight. Comprehensive testing included compressive strength, water demand, setting time, heat of hydration, acid resistance, and microstructural analysis. Results demonstrated that increasing FA fineness reduced water demand by up to 6.3% (Type I) and 5.9% (Type II) at 30% replacement, while enhancing long-term strength. Mortars with 10% GFA2 achieved 58.6 MPa at 56 days. Type II OPC blends exhibited superior acid resistance, with mass loss reductions of 43% (50% GFA2) compared to Type I, attributed to lower C₃A content and denser microstructures. Hydration heat decreased by 10.9% in Type II OPC, further reduced by 40% with 50% FA replacement. The microstructural analysis confirmed reduced ettringite formation and enhanced compactness in FA-modified mortars, correlating with improved durability. These findings highlight the viability of finely ground FA as a sustainable supplementary material, enabling highvolume FA utilization (up to 50%). The study provides critical insights for optimizing greener cement formulations, particularly in regions prioritizing Type II OPC for sulfate resistance and moderate heat applications, advancing Malaysia’s net-zero carbon goals through reduced clinker reliance

Spider Haiku

The utilization of lightweight oil palm shell to produce high strength lightweight sustainable material has led many researchers towards its commercialization as structural concrete. However, the low tensile strength of Oil Palm Shell Concrete (OPSC) has hindered its development. This study aims to enhance the mechanical properties and flexural behaviours of OPSC by the addition of steel fibres of up to 3% by volume, to produce oil palm shell fibre-reinforced concrete (OPSFRC). The experimental results showed that the steel fibres significantly enhanced the mechanical properties of OPSFRC. The highest compressive strength, splitting tensile and flexural strengths of 55, 11.0 and 18.5 MPa, respectively, were achieved in the OPSFRC mix reinforced with 3% steel fibres. In addition, the flexural beam testing on OPSFRC beams with 3% steel fibres showed that the steel fibre reinforcement up to 3% produced notable increments in the moment capacity and crack resistance of OPSFRC beams, but accompanied by reduction in the ductility

Effect of aggressive chemicals on durability and microstructure properties of concrete containing crushed new concrete aggregate and non-traditional supplementary cementitious …

The increasing awareness and usage of traditional supplementary cementitious materials (SCMs) in concrete have pressured the construction industry to look for alternatives to overcome the concerns over their plentiful availability in the future. This research illustrates the performance of recycled aggregate concrete prepared with the incorporation of available industrial by-products, namely rice husk ash (RHA), palm oil fuel ash (POFA) and palm oil clinker powder (POCP) as alternatives for traditional SCMs. The effect of hydrochloric (HCl) acid and magnesium sulfate (MgSO 4) attack was evaluated by measuring the change in mass, compressive strength and microstructural analysis. The results revealed that the incorporation of RHA, POFA and POCP up to 30% minimizes concrete deterioration and loss in compressive strength when the specimens were exposed to HCl solution. In addition, the scanning electron

Evaluation of industrial by-products as sustainable pozzolanic materials in recycled aggregate concrete

The utilization of traditional supplementary cementitious materials (SCMs) has become more intense in the concrete industry due to their better long-term properties. This research evaluates the fresh and hardened properties of concrete that was developed using a high amount of recycled aggregate (RA) incorporated with sustainable SCMs. Rice husk ash (RHA), palm oil fuel ash (POFA) and palm oil clinker powder (POCP) were used as SCMs at 10%, 20% and 30% cement replacement levels to investigate their positive role in the performance of RA concrete. The results showed that the 10% replacement level of cement by RHA produced the highest strength at all ages tested. Although POFA and POCP were found to negatively affect the strengths at an early age, the hardened properties showed improvement after a relatively long curing time of 90 days. In addition, the targeted compressive strength of 30 MPa was achieved by using SCMs at levels up to 30%. Overall, the sustainable SCMs can reduce the quantity of cement required for concrete production, as well as reduce the conventional cement with the industrial by-products, which are considered as waste materials; thus, the concrete produced using up to 30% of SCMs as a replacement for cement could be considered as more environmentally-friendly concrete

Assessment on engineering properties and CO2 emissions of recycled aggregate concrete incorporating waste products as supplements to Portland cement

This paper presents an experimental investigation on the durability properties and carbon dioxide (CO2) emissions of concrete developed using waste products. The concrete comprised of recycled concrete aggregate (RA) as a complete coarse aggregate replacement. In addition, rice husk ash (RHA), palm oil fuel ash (POFA) and palm oil clinker powder (POCP) were used as replacement materials for cement at levels up to 30%. The supplementary cementitious materials (SCMs) were used in RA concrete with the aim of reducing the dependency on cement as a stand-alone binder. The compressive strength, water absorption, chloride-ion penetration and electrical resistivity were investigated for RA concrete containing SCMs. Moreover, the residual compressive strength was also examined along with the weight loss to check the elevated temperature resistance of RA concrete with SCMs. The results revealed that