Weight Of Total Binder Research Articles

Different Statistical Modeling to Predict Compressive Strength of High-Strength Concrete Modified with Palm Oil Fuel Ash

The present study focuses on proposing various statistical models, such as linear regression (LR), nonlinear regression (NLR), and artificial neural network (ANN), to forecast the compressive strength of environmentally friendly high-strength concrete, incorporating waste agricultural material like palm oil fuel ash (POFA). A dataset of 105 experimental observations was compiled from existing literature to achieve this goal, which was subsequently partitioned into training and testing subsets. Each model was developed based on the training data and evaluated using the testing data. The performance of each proposed model was gauged using diverse statistical metrics like the coefficient of determination, mean absolute error, root mean square error, and scatter index to identify the most effective model. The findings indicate that using POFA with a finer particle size exerts a greater influence on the concrete's properties. The replacement was done using the weight method, and the predicted equation worked with the variation of the used rate of POFA from 0 to 60% of total binder weight. Substituting a portion of cement with POFA leads to a reduction in the heat of hydration and an extension of the setting time. The optimal percentage of POFA is 30%, yielding mechanical properties superior to those of the control mixture, particularly in the later stages of development. Among the models considered, the ANN demonstrates superior efficiency and accuracy in predicting the compressive strength of conventional concrete modified with POFA compared to LR and NLR models. This is evident in the ANN's higher R2 values of 52% and 16%, respectively, and a lower scatter index below 0.1%.

Rheological and Aging Characteristics of Polymer-Modified Asphalt with the Addition of Sulfur

Crosslinking agents, notably sulfur, are used in asphalt binder modification to facilitate chemical bonding between polymer chains and the asphalt binder. Despite some prior research indicating the benefits of sulfur crosslinking in enhancing polymer-modified asphalt’s (PMA) stability, there is a lack of comprehensive understanding regarding its impact on rheological properties and its anti-aging potential. This study addresses these gaps by thoroughly investigating the effects of varying the sulfur content (ranging from 0.03% to 0.5% by total weight of binder) on PMA’s rheological properties. The research assesses the effectiveness of sulfur in enhancing PMA’s resistance to aging using various methods, including the Glover-Rowe parameter, FTIR analysis, and the examination of the dynamic modulus and phase angle master curves. The results indicated that the addition of sulfur, particularly up to 0.3%, bumps the high-temperature performance grade by one level, and significantly improves elasticity, allowing the PMA to support heavier traffic without experiencing rutting, all while maintaining resistance to low-temperature cracking. Furthermore, PMA with sulfur demonstrated an increase in resistance to aging, reducing the aging potential by approximately 15% with the best sulfur formulation. This enhanced durability can reduce the frequency of maintenance activities, leading to cost savings, reduced roadwork emissions, and prolonged pavement life.

Effect of re-aging on chemical and rheological properties of waste engine oil rejuvenated asphalt binder

The use of rejuvenator can potentially restore original properties of reclaimed asphalt pavement (RAP) materials to achieve the purpose of reuse, but less attention has been paid to the aging properties of rejuvenated asphalt binders. In this study, original asphalt binder, aged binder and the rejuvenated binders with 3 %, 6 %, and 9 % of rejuvenator by total weight of binder were prepared first. Then the five rejuvenated binders were subjected to the oven aging. Based on the results from Fourier Transform Infrared Spectroscopy and Dynamic Shear Rheometer, the chemical and rheological properties of the five binders were investigated due to re-aging. It is showed that the of carbonyl index of the rejuvenated binders and original binder increase rapidly during the fast-aging state and then slowly during the constant-aging state, while aged binder increases approximately linearly. The rheological properties indexes such as complex shear modulus, phase angle δ, crossover frequency, crossover modulus, rheological index, G-R parameter and rutting factor of the five binders were determined, and the variation of these indexes are similar or opposite to carbonyl index during aging. Aging performances of the five binders were investigated using the oven aging indexes. It is showed the rejuvenated binders with more dosage of rejuvenator have faster aging rate and more obvious effects on the aging rheological behavior. The rheological properties of the aged binder are less affected by the re-aging. Among the rheological property indexes, the G-R-based oven aging index is most susceptible to the re-aging. There are some certain close relationships between the chemical property change and rheological property evolution during re-aging for the five binders, without considering the aging times and the dosage of rejuvenator.

Strength development and microstructure evaluation of cement mortar incorporating various waste red brick powder

This research aims to evaluate the strength development and microstructure of a green mortar produced from waste red brick powder (WRP) as a partial cement replacement. The mortar samples were prepared with various WRP content of 0%, 10%, 20%, 30%, and 40% of total binder weight, and the w/b was fixed at 0.4. The fresh properties were checked by flowability and fresh unit weight. While the compressive strength was conducted up to 28 days. The mortar samples exhibited a reduction in flowability and unit weight with increasing WRP content. The incorporation of 10%-20% WRP improved the compressive strength of mortar samples at 28-day, while the compressive strength reduced with higher WRP content (30%-40%). The C-S-H/CaCO3 gel, Ca(OH)2 and ettringite were hydration products of WRP mortar samples. The incorporation with WRP significantly reduced the Ca(OH)2 content

Effects of treated biomass wood fly ash as a partial substitute for fly ash in a geopolymer mortar system

The use of biomass for energy production is becoming increasingly common. However, one of the significant problems when using biomass is the ash produced in the incineration process. Existing studies have shown the possibility of using residual biomass ashes in cement-treated materials, but its low properties have reduced compressive and flexural strength. Accordingly, some treatment methods research has also been done to enhance the properties of biomass waste materials for incorporation into the concrete matrix. On the other hand, there is a growing interest in replacing conventional ordinary Portland cement with geopolymer composite as the binder matrix in concrete due to increasing global environmental issues like greenhouse gas emissions. Therefore, this study investigates the effect of the treatment process on the physical and mechanical performance of geopolymer mortar incorporating Biomass Wood Fly Ash (BWFA) and Fly Ash (FA) for industrial applications. BWFA was treated through calcination and ball milling techniques. Both non-treated and treated BWFA were used to replace FA at different replacement ratios: 0 %, 10 %, 30 %, and 50 % by total binder weight. Test specimens were evaluated regarding porosity, compressive strength, flexural strength, X-ray diffraction analysis, thermogravimetric analysis, and microstructure development at ages 1, 3, and 7 days. The outcomes demonstrated considerable improvements in treated mortars' physical and mechanical characteristics. The inclusion of treated BWFA enhanced compressive and flexural strength. Besides, the Control mix and treated BWFA specimens performed better porosity while non-treated BWFA specimens showed better thermogravimetric performance.

Effect of silica fume on compressive strength of ultra-high-performance concrete made of calcium aluminate cement/fly ash based geopolymer

The study on geopolymers blended with silica fume is scant. This study investigates the effects of silica fume (SF) on the compressive strength of geopolymer-based ultra-high-performance concrete (G-UHPC) subject to ambient curing. Low-calcium fly ash (LCFA) and calcium aluminate cement (CAC) were activated by a combination of sodium hydroxide and sodium silicate solution to produce geopolymer binders. Effects of the CAC content, alkaline solution to binder (A/B) ratio, and sodium hydroxide (SH) concentration on the flowability and compressive strength of geopolymer binders were studied. The SF dosage varied from 5% to 30% of the total binder weight, and the Taguchi method was used to determine the optimum mix proportions. The incorporation of SF showed a complicated influence on the compressive strength, depending on the CAC content. For mixes with 20% CAC content, the compressive strength increased with increasing SF dosage. But for mixes with 10% CAC content, a high SF dosage (>10%) negatively influenced the compressive strength. The mechanisms for this contradictory behavior were discussed based on the X-ray diffraction and scanning electron microscopy analyses. The inclusion of steel fibers has a positive influence on the mechanical properties of G-UHPC. The G-UHPC mix with 1.5 vol% steel fibers achieved a compressive strength of 139.1 MPa and flexural strength of 13.5 MPa at 28 days. • Geopolymer-based UHPC was developed by incorporating calcium aluminate cement. • Taguchi analysis was used to optimise mixture compositions for geopolymer-based UHPC. • Effects of silica fume on the strength were explained via SEM and XRD analyses. • Effects of steel fiber on the mechanical properties were evaluated.

The effect of materials and curing system on the behavior of self-compacting geopolymer concrete

Abstract The aim of the present work was to investigate and achieve the optimum compressive strength of self-compacting geopolymer concrete (SCGC). Fly ash (FA) and ground granulated blast furnace slag (GGBFS) are used at different ratios as binder materials to produce the SCGC mixes. Alkaline solution was a mix of sodium silicate and sodium hydroxide. Three different ratios of binder materials were used to produce SCGC (0FA-100GGBFS; 50FA-50GGBFS; and 100FA-0GGBFS). The total binder weight was 500 kg/m3 within a constant alkali–binder proportion (0.5). Two curing conditions were used, at ambient environment and heat curing at 110°C for 24 h. The compressive strength and fresh properties of SCGC are evaluated. The compressive strength is utilized to demonstrate the mechanical properties of SCGC. The compressive strength is investigated at two ages (7 and 28 days). The results showed that the use of GGBFS had a negative effect on the fresh properties of SCGC. However, it has a significant impact on the mechanical behavior of the SCGC. SCGC’s early strength is heavily involved in heat curing. The compressive strength of 100% GGBFS in the ambient environment after 28 days was more than that of GGBFS cured at 110°C. The optimum eco-friendly mix is 50FA-50GGBFS.

Experimental characterization of the oxidative kinetic aging behavior of rejuvenated asphalt binder

• Rejuvenated binders were subjected to over-aging at various temperature and time. • The effect of temperature, duration and rejuvenator dosage on the oxidative aging mechanisms of rejuvenated binders were revealed. • Oxidative aging increased the viscoelastic behavior of rejuvenated binders while rejuvenator reduced. • The effect of rejuvenator on viscoelastic behavior of rejuvenated binders weakened gradually during oxidative aging. Rejuvenator is commonly used in reclaimed asphalt pavement (RAP) to improve the properties of the blended binder. However, the rejuvenated binder would experience aging again and cause the rejuvenated asphalt mixture prone to durability issues. This study focused on evaluating the impact of oxidative aging on the chemical and rheological properties of rejuvenated binder (RB) by means of Fourier Transform Infrared Spectroscopy and Dynamic Shear Rheometer. First, the aged binders blended with waste engine oil used as the rejuvenator at 0%, 3%, 6%, and 9% by total weight of binder. Then, laboratory oven aging procedures were employed to the RB binders at different aging temperatures and periods. Carbonyl content were determined to understand the effect of temperature and duration on the oxidative aging mechanisms of RB binders. Each RB binder had its specific fast and constant oxidative rates. With the increase of rejuvenator dosage, the temperature sensitivity of RB binders decreased in the constant rate stage and increased in the fast rate stage. The high-temperature true performance grade (HTPG) of RB binders increased with the aging time and temperature, and the effect of rejuvenator dosage on HTPG decreased gradually with aging duration. Based on the master curves of complex modulus and phase angle, the aging time and aging temperature increased the viscoelastic behavior of RB binders, and rejuvenator reduced the viscoelastic behavior, but the effect of rejuvenator lowered gradually during oxidative aging. The crossover frequency, rheological index and Cole-Cole plot demonstrated the aging decreased the viscous components and increased the elastic behavior of the RB binders. As the rejuvenator dosage increased, the viscous component of the aged RB binders increased, and the elastic behavior decreased as well as more transition behavior from viscous to elastic.

Experimental investigations on mechanical properties of normal and high strength high calcium geopolymer concrete

Alkali activated (Geopolymer) concrete is an excellent and viable alternative to Portland cement based concrete as it can be produced using industrial by-products such as Ground Granulated Blast Furnace Slag (GGBS) and fly ash (source of reactive alumino-silicates) along with less energy craving ingredients such as alkali activators. In this study, slag based geopolymeric concrete mixes of M40 and M80 grade were prepared using GGBS and fly ash in proportion of 70:30 by weight. Geopolymeric binder was activated using combination of Sodium hydroxide and Sodium Silicate. Activator modulus (i.e. SiO2 / Na2O) was maintained as 1 and Na2O was kept as 7% and 8% by weight of total binder respectively for M40 and M80 grade geopolymeric concrete mixes. Both the concrete mixes were evaluated for fresh properties of concrete (slump and air content) along with mechanical properties of hardened concrete. Performance of geopolymeric mixes was compared with two conventional concrete mixes of equivalent grade (i.e. M40 and M80) in terms of aforementioned mechanical properties. Study concludes that slag based geopolymer concrete mixes of a particular strength were developed at significantly lower total binder content in comparison to cementitious binder required for development of conventional Portland cement based concrete of equivalent strength. Early age compressive strength of normal strength geopolymeric concrete mixes is higher in comparison to conventional concrete mix. Modulus of elasticity and Poisson’s ratio of geopolymeric mixes of both normal and high grade are observed to be lower in comparison to their corresponding conventional concrete mixes of equivalent strength.

An Eco-Sustainable Production of Cement Mortar Containing Waste Glass as Partial Replacement of Cement

1.1 BackgroundGlass, with its variety of forms, is a typical amorphous material that whenrecycled for numerous times, it may maintain similar chemical properties. Preliminary examination and pozzalanic activity index testing exhibited compliance with specifications and a potential for use as a supplementary cementitious material. The effects of replacement percentages that ranged from 0-20% by the total binder weight on various fresh, hardened, durability and microstructure properties were investigated. The percent of replacement 20% of glass powder (GP) by the total binder weight revealed the highest results for strength mortar. Expansion due to alkali silica reaction (ASR) reduced considerably with the increased GP content, and a level of 20% GP has exhibited the best ASR resistance. Rate of water absorption was found to reduce with replacements in the range up to 15%, indicating more impedance to capillary water permeability and expected improved durability. XRD results suggest that GP has a positive effect on the consumption of portlandite, especially in the higher percent. An average glass content of 15-20% was found optimal to produce an eco-sustainable mortar where cement is partially replaced with as much waste material as possible, and that achieves high levels of mechanical characteristics.

Flexural performance of reinforced Alkali-activated concrete beams incorporating steel and structural Macro synthetic polypropylene fiber

Lately, alkali-activated concrete (AAC) has gained attention due to the environmental impact that Ordinary Portland Concrete (OPC) possesses and durability issues. This paper investigates the flexural behavior of reinforced AAC beams adding 1.5% structural macro synthetic polypropylene fiber and 5% hooked end steel fiber structural, including control. The fiber addition was relevant to the total binder weight. Six beams of 100 mm × 200 mm × 1200 mm beams reinforced with two steel bars of 12 mm in diameter were cast and tested under a four-point loading test. This study evaluated the cracking moment, ultimate load, mid-span deflection, energy absorption, toughness, displacement ductility, failure mode, and crack patterns at yielding and ultimate capacity. The addition of fibers, especially steel fibers, significantly increased the flexural capacity. The steel fiber addition to the AAC beam specimen showed remarkable failure mode. It disturbed the crack pattern due to the fiber action that acted as a bridge controlling the crack propagation and transferring stress from the AAC to the steel fibers. Also, this study evaluated several codes and guidelines provisions in terms of flexural capacity and deflection. The ACI 318 showed conservative predictions rather than ECP 203 and EN 1992–1. Furthermore, a finite element model (FEM) using “ANSYS” was developed and validated. The FEM results provided a good agreement with the experimental results.

Evaluation of combined utilization of marble dust powder and fly ash on the properties and sustainability of high-strength concrete.

With the recent increase in demand for high-strength concrete, higher cement content is utilized, which has increased the need for cement. The cement industry is one of the most energy-consuming sectors globally, contributing to 10% of global carbon dioxide (CO2) gas emissions and global warming. Similarly, with rapid urbanization and industrialization, a vast number of by-products and waste materials are being generated in abundance, which causes environmental and health issues. Focusing on these two issues, this study aimed to develop an M50-grade eco-friendly high-strength concrete incorporating waste materials likemarble dust powder (MDP) and fly ash (FA) as partial cement replacement. 2.5%, 5%, 7.5%, and 10% MDP and FA by weight of total binder was utilized combinedly, such that the 5%, 10%, 15%, and 20% cement content was replaced, respectively. The fresh state properties in terms of workability and hardened state properties in terms of compressive and flexural strengths were evaluated at 7, 14, 28, 56, and 90days. Furthermore, to assess the environmental impact of MDP and FA, the embodied carbon and eco-strength efficiency were calculated. Based upon the results, it was observed that acombined 10% (5% MDP and 5% FA) achieved the highest strength; however, 15% (7.5% MDP and 7.5% FA) substitution could be optimal. Furthermore, the combined utilization of FA and MDP also enabled a reduction in the total embodied carbon. It decreased the cost of concrete, resulting in an eco-friendly, high-strength concrete.

Influence of Graphene Nanoplatelets on the Compressive and Split Tensile Strengths of Geopolymer Concrete

Geopolymer is now a more advanced alternative to cement and available substitute for OPC while graphene nanoplatelets (GnP) are new nanomaterials with extraordinary properties that can enhance and improve the strength of cementitious materials. Although graphene reinforced concrete has intriguing potential, its implementation in construction requires better knowledge of the impact of GnP on the properties of concrete related to durability. Studies on the compressive and tensile strength performance of geopolymer concrete (GPC) containing GnP are needed. The present study investigated the influence of reinforcing GPC with varying percentages of GnP on the compressive and split tensile strengths of GPC. The addition of GnP ranged from 0.0%, 0.25% and 0.5% by weight of total binder. It has been observed that the addition of GnP increased the compressive strength by 30% and the tensile strength by 22% in comparison to a reference sample with a specified composition of fly ash and sodium metasilicate. In addition, the effect of GnP on enhancing the compressive strength of the geopolymer was shown to diminish as the amount of sodium metasilicate increased.

Combined effect of coconut shell and sugarcane bagasse ashes on the workability, mechanical properties and embodied carbon of concrete.

This experimental research was conducted to study the combined effect of agricultural by-product wastes on the properties of concrete. The coconut shell ash (CSA) was utilized to substitute cement content ranging from 0 to 20% by weight of total binder and sugarcane bagasse ash (SCBA) to substitute fine aggregates (FA) ranging from 0 to 40% by weight of total FA. In this regard, a total of 300 concrete specimens (cylinders and cubes) were prepared using 1:1.5:3 mix proportions with a 0.52 water-binder ratio. The study investigated the workability, density, permeability, and mechanical properties in terms of compressive and splitting tensile strengths. Additionally, the total embodied carbon for all mix proportions was calculated. It was observed that with an increase in CSA and SCBA contents, the workability, density, and permeability reduced significantly. Due to CSA and SCBA being pozzolanic materials, a gain in compressive and splitting tensile strengths was observed for certain concrete mixes, after which the strength decreased. The increase in embodied carbon of SCBA increased the total embodied carbon of concrete; however, it can be said that C15S40 which consists of 15% CSA and 40% SCBA is the optimum mix that achieved 28.75 MPa and 3.05 MPa compressive and tensile strength, respectively, a reduction of 4% total embodied carbon.

Evaluating fresh state, hardened State, thermal expansion and bond properties of geopolymers for the repairing of concrete pavements under restrained conditions

In this study, slag-based geopolymer concretes, including partial dosages of pumice and silica fume, are employed as repair materials for deteriorated concrete pavements. Pumice and Silica fume were used to improve the fresh properties of geopolymer concrete, specifically the setting time. In this regard, a series of mixtures were prepared with 0%, 5%, 10%, and 15% replacements of pumice and silica fume by weight of total binder in slag-based geopolymers concrete, while maintaining the percentage of other parameters. Then, the characteristics of fresh and hardened states of concretes constructed using these geopolymers were investigated. The parameters studied include setting time, slump, fresh density, mechanical strength (compressive, tensile, and flexural), bonding behavior, drying shrinkage (free and restrained), coefficient of thermal expansion, water absorption, and porosity. In addition, the effect of the roughness of the substrate layer on the shrinkage of the repair layer was evaluated. The results showed that the addition of pumice and silica fume increased the setting time and workability of fresh concrete, reduced the compressive, tensile, and flexural strength, and maintained the bond strength with no significant effect. It also increased the thermal expansion coefficient and shrinkage. Moreover, water absorption and porosity increased due to the increase in the amount of pumice and silica fume. Finally, the results confirmed that the roughness of the substrate layer has a significant effect on the shrinkage cracking of the repair layer.

Effect of Combined Supplementary Cementitious Materials on the Fresh and Mechanical Properties of Eco-Efficient Self-Compacting Concrete

Global concrete demand is causing depletion of natural resources at an alarming rate. Self-compacting concrete (SCC) is an innovative solution as it uses less aggregates; however, the drawback of SCC is that high cement content is required compared to conventional concrete. Considering that cement production emits 7% of carbon dioxide (CO2) gas emissions, the use of high content of cement in SCC production is concerning. Though the high powder content of SCC may be of a concern, however, it allows the opportunity to substitute the cement content with supplementary cementitious materials. This experimental work was therefore conducted to reduce the cement content by substituting it with waste materials, such as eggshell powder (ESP) and palm oil fuel ash (POFA), and develop an eco-efficient SCC. The cement content was partially substituted by 0 to 5% ESP and 0 to 15% POFA by weight of total binder. A total of 90 cubes of 100 mm and 60 cylinders of 100 × 200 mm dimension were prepared to evaluate the compressive and splitting tensile strengths, modulus of elasticity, and Poisson’s ratio. Furthermore, the environmental impact assessment was conducted to assess the embodied CO2 and eco-strength efficiency of the developed eco-efficient SCC. It was found that the combination of POFA and ESP increased pozzolanic reactivity, developing additional calcium silicate hydrate gels, thus increasing strength. The combination of 2.5% ESP and 5% POFA (a total of 7.5% cement substitution) was deemed to be the optimal combination as it provided better strength in SCC after 28 days of curing, which leads to 9.66% higher compressive strength than the control SCC. Furthermore, the developed SCC was observed to be eco-friendly as it reduced embodied carbon ranging from 3.86 to 15.33% and eco-efficiency ranging from 2.38 to 15.48% on 28 days compared to the control SCC.

The performance of fiber GGBS based alkali-activated concrete

The fast construction and renovation of roads and bridges and the infrastructures in Egypt and developing countries cause concrete and cement production on a large scale. This huge market demand for precast units and concrete production harms the environment and global warming. Thus, the Ordinary Portland Cement (OPC) should reduce by developing new materials such as geopolymer concrete or alkali-activated concrete. This study investigated alkali-activated slag concrete (AAC) performance reinforced with structural polypropylene and steel fibers cured at ambient room temperature. The structural polypropylene and steel fibers were incorporated into the alkali-activated mix by 1.5% and 5% of the total binder weight, respectively. A wide range of engineering properties was assessed, including compressive strength, split tensile strength and stress-strain behavior, density, water absorption, and porosity. Microstructural analysis of the AAC samples was evaluated through scanning electron microscopic (SEM). The results showed that compressive strength at 1-day curing developed about 85% of the compressive strength for ACC at 28-days, which was considered as early high strength. A 10% enhancement of the AAC specimens' average compressive strength was reported after 7 and 28 days while fiber addition. The split tensile strength significantly increased by 19.28 and 26.80% by incorporating structural polypropylene and steel fibers, respectively. Comparison between the ACI 318 and ECP 203 provisions was handled along with those experimental results obtained elastic and rupture modulus. The ACI 318 provisions provided a more conservative prediction to the experimental results than the ECP 203 provision, which overestimated the experimental values by an average value of 1.1. The electron microscopy images confirmed the improvement in the engineering properties by showing a proper and coherent bond between the mortar matrix and the added fibers.

The usage of recycled materials on hot mix asphalt

The demand for fresh aggregates increases as the number of road maintenance and/construction project increases. However, continually mining fresh aggregates will result in irrecoverable environmental damage, and thus, engineers are looking for alternatives aggregates that are more environmentally friendly to be used. The paper discussed the usage of several recycled materials that were mixed with hot mix asphalt (HMA) to be used as surfacing pavement layer, including coconut fibre, Styrofoam, crumb rubber, and recycled asphalt pavement (RAP). A number of tests, which are Marshall, Cantabro Loss, and Indirect Tensile Strength tests were used to evaluate the performance of the asphalt mixtures that were mixed with recycled materials. Both coconut fibre and RAP were mixed as filler or substitute for fresh aggregates, while both Styrofoam and crumb rubber were melted and mixed with the binder. It is found that best amount for coconut fibre, RAP, Styrofoam, and crumb rubber to be added to the HMA are 0.6% of total binder weight, 100% of coarse aggregates, 2.5% of the binder weight, and 3% of total mixture weight, respectively.

Thermo-mechanical properties and sustainability analysis of newly developed eco-friendly structural foamed concrete by reusing palm oil fuel ash and eggshell powder as supplementary cementitious materials.

The production of cement contributes to 10% of global carbon dioxide (CO2) pollution and 74 to 81% towards the total CO2 pollution by concrete. In addition to that, its low strength-to-weight ratio, high density and thermal conductivity are among the few limitations of heavy weight concrete. Therefore, this study was carried out to provide a solution to these limitations by developing innovative eco-friendly lightweight foamed concrete (LFC) of 1800 kg/m3 density incorporating 20-25% palm oil fuel ash (POFA) and 5-15% eggshell powder (ESP) by weight of total binder as supplementary cementitious material (SCM). The influence of combined utilization of POFA and ESP on the fresh state properties of eco-friendly LFC was determined using the J-ring test. To determine the mechanical properties, a total of 48 cubes and 24 cylinders were prepared for compressive strength, splitting tensile strength and modulus of elasticity each. A total of 24 panels were prepared to determine the thermal properties in terms of surface temperature and thermal conductivity. Furthermore, to assess the environmental impact and eco-friendliness of the developed LFC, the embodied carbon and eco-strength efficiency was calculated. It was determined that the utilization of POFA and ESP reduced the workability slightly but enhanced the mechanical properties of LFC (17.05 to 22.60 MPa compressive strength and 1.43 to 2.61 MPa tensile strength), thus satisfies the ACI213R requirements for structural lightweight concrete and that it can be used for structural applications. Additionally, the thermal conductivity reduced ranging from 0.55 to 0.63 W/mK compared to 0.82 W/mK achieved by control sample. Furthermore, the developed LFC showed a 16.96 to 33.55% reduction in embodied carbon and exhibited higher eco-strength efficiency between 47.82 and 76.97%. Overall, the combined utilization of POFA and ESP as SCMs not only enhanced the thermo-mechanical performance, makes the sustainable LFC as structural lightweight concrete, but also has reduced the environmental impacts caused by the disposal of POFA and ESP in landfills as well as reducing the total CO2 emissions during the production of eco-friendly LFC.

Structural behavior of MRPC beams exposure to riverine simulated circumstances using GFRP and CFRP bars

Reinforced polymer bars could potentially be used with fiber as a strengthening technology in MRPC. The main objective of this paper is to study the influence development of the flexural behavior of MRPC beams after 120 days of virtual corrosion-exposure in riverine simulated circumstances using GFRP and CFRP bars. Nine beams were tested via a two-point loading method up to failure, 1200 mm long, (200x100mm) cross-section. The water/binder is chosen to be 0.14 by weight. Silica fume was replaced by 8% weight of cement. The dose of superplasticizer used to the total binder weight was 0.41 percent. Three types of flexural reinforcement ratios were used individually per each cross-section; GFRP, CFRP, and traditional steel rebar, with a nominal diameter of 10 mm. The compressive strength of MRPC is 80 MPa. The experimental evidence indicates that GFRP and CFRP bars used with MRPC have higher tensile strength and anti-corroded bars. Also, the load results indicate that CFRP bars are more efficient than GFRP bars and steel rebar. Finally, the behavior of MRPC beams neither GFRP and CFRP bars submerged in Tigris river water did not chemically affect. The author recommended replacing steel rebar with GFRP and CFRP bars to improved structural behavior.