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With the increased use of engineered cementitious composite (ECC) in closed environments and as a structural material, it is necessary to fully understand its performance under elevated temperatures. This research investigates the response of ECC to ambient and elevated temperatures and addresses the issue of explosive spalling by incorporating graphene oxide (GO) and crumb rubber (CR). Twenty GO-modified rubberized ECC mixes were designed using Response surface methodology (RSM), considering GO content, GO concentration for CR pretreatment, CR replacement of fine aggregate, and elevated temperature as the input variables. Results show that mixes with GO and GO-treated CR outperform those without GO or untreated CR at ambient and elevated temperatures. Response predictive models exhibited high coefficient of determination (R2) values ranging from 84 % to 96 %. Multi-objective optimization yielded optimum input factors, resulting in improved mechanical properties that were experimentally validated to confirm the accuracy of the developed models.

A crucial aspect of the design approach for bar-reinforced concrete buildings is the proper transfer of loads between the concrete and steel reinforcement via bonding. Bar pull-out tests were done to see how graphene oxide (GO) affected the bond strength, bond energy, and bond stress–slip response of deformed reinforcing bars implanted in engineered cementitious composites (ECC). This was done to improve the bond strength of steel/concrete composites. This article examines the bonding behaviour of steel reinforcing bars in a mixture of GO-modified ECC. The findings of pull-out assessments conducted on two distinct diameters (12 and 16 mm) of reinforcement steel bar inserted in ECC are initially provided. The investigation's findings are then utilised to determine the bond-slip interactions that describes the relations between the ECC mixtures and steel reinforcement bars. According to the experiment results, the introduction of GO as a nano-reinforcement in the ECC mixture had a considerable positive effect on the bar-matrix interactions owing to its bridging function. After 28 days, the bond strength of steel bars with widths of 12 and 16 mm was increased by 54.80% and 26.70%, respectively, when 0.05 wt% of GO was added to 1% of PVA fibre. The response surface methodology (RSM) is employed for developing predictive algorithms, which are then utilised in performing multi-variate optimization on bond-slip parameters, including bond strength, bond slip and bond energy. The acquired actual and predicted findings suggest that the created models are adequate for interpreting the bond performance of reinforcement steel bars in the GO-ECC.

The overuse of conventional fuels (coal, petroleum products, and gas) for energy generation causes natural resource depletion and global warming. Therefore, the utilization of Renewable Energy Sources (RES) in power systems is seeing rapid growth on a global level, particularly in offshore locations. This work aims to review the progress in developing hybrid RES power systems in offshore environments and optimization methods used for power generation using solar, wind, and wave energy systems. The papers published in peer-reviewed journals were collected from 2000 to 2023. A total of 143 articles were obtained and analyzed. The results demonstrated a rising trend in annual publications about the use of hybrid RES in electricity generation since 2007. The hybrid solar-wind and wind-wave energy systems have received a lot of attention due to technical advancements already developed for the wind energy system. Machine learning techniques, such as genetic algorithms (GA) and particle swarm optimization (PSO), have been extensively utilized in the field of renewable energy systems for tasks such as optimizing unit sizes, determining appropriate unit placements, minimizing costs, and maximizing power output. The methods are preferred due to their less complex structure. However, the practical application, true cost estimation and installation and maintenance studies at offshore locations are poorly developed. Also, the hybrid solar-wave and solar-wind-wave RES systems need further investigations for optimal mixing at the feasibility stage. The current review is the first of its kind, focusing on offshore renewable energy systems only.

Waste materials may be used as raw materials for interlocking masonry products in order to contribute to sustainable development and environmental protection. Rubberized concrete Interlocking Brick (RCIB) was developed by volumetric replacement of 56% of the ordinary Portland cement with fly ash and 20% of the sand with crumb rubber (CR) to reduce the production cost of conventional concrete bricks (CCB) and restrict the depletion of natural resources and contributing to solving the environmental problems associated with the accumulation of scrap tires in landfills. The mechanical and sustainability evaluation of masonry prism made of the developed brick is the aim of this research. Consequently, compressive strength, failure mechanism, stress–strain behaviour, and energy absorption of grouted and ungrouted prisms made of RCIB were measured experimentally under axial compression load. The thermal resistance, fuel consumption, CO2emission, and cost analysis of RCIBs were estimated. The findings reveal that grout had a significant impact on the compressive strength of rubberized concrete interlocking masonry prisms where the compressive strength of grouted and ungrouted prisms was 10.99 MPa and 5.83 MPa, respectively. Web splitting and vertical cracks were the common failure modes observed in both prisms. Moreover, the rubberized concrete interlocking masonry prisms revealed greater energy absorption as well as a gradual and ductile failure mechanism. The RCIB exhibited higher thermal resistance than CCB (increased from 0.106 to 0.171 m2 K/W) which could contribute to a 62% reduction in annual fuel consumption and CO2emission. Further, more than 25% of the material cost could be saved.

Crumb rubber (CR) pretreatment methods effectively mitigate mechanical strength loss in cementitious composites. Yet, their impact on composite durability remains underinvestigated. This study examines the effect of CR pretreatment with graphene oxide (GO) on the durability of rubberized engineered cementitious composite (RECC), employing response surface methodology (RSM) for predictive model development and optimization. Water absorption, sulfate and acid resistance, compressive strength, and the porosity using mercury intrusion porosimetry were evaluated across 16 RSM-generated mixes using five GO concentrations (GOC) (0–1 mg/mL) and three pretreated CR (PCR) replacement levels (1–5%) as input variables. Results reveal increased resistance to water absorption, expansion, weight, and strength loss in sulfate and acid media with higher GOC levels across all PCR groups. Developed response predictive models demonstrate high R2values (53–97%). Optimization resulted in 0.73 mg/mL and 2.5% for GOC and PCR, respectively.

The Disposal of Scrap Tires has Resulted in Major Environmental Problems Worldwide. Therefore, Utilizing Scrap Tires as Crumb Rubber is being Used in Brick Production to Improve the Properties of the Bricks as well as to Provide Feasible Waste Management of Scrap Tires. this Study Presents the Literature Research on Utilizing Crumb Rubber in Bricks Manufacturing. the Review Summarized the Manufacturing Process of Producing Crumb Rubber and then Documented the Application of Crumb Rubber in Masonry. the Results Show that the Compressive Strength of Masonry Bricks Decreases with the Increased Percentage Substitution of Crumb Rubber as a Replacement of Fine Aggregate while the Water Absorption Increased. Moreover, the Addition of Crumb Rubber in Masonry Applications Reduce the Density which Produce Lightweight Masonry Products. Generally, the Findings Confirmed that the Masonry Bricks Incorporated Crumb Rubber Exhibit Good Physical and Mechanical Properties. the Usage of Crumb Rubber in Bricks Making Helps to Solve Problems Associated with Scrap Tire Management all over the World.

Roller-compacted concrete (RCC) is being widely used in highway construction industry (for pavement applications) due to its enormous advantages over conventional concrete rigid pavement. However, the major problems related to RCC pavement are the rigidity and relative tendency to crack due to low tensile strength. To address this problem, crumb rubber (CR) can be added as partial replacement of fine aggregate. High elastic and deformation properties of CR will increase the ductility of RCC pavement to absorb the deformation and strain energy caused by traffic loads. However, incorporating CR to RCC pavement leads to a reduction in mechanical properties which needs to be addressed for proper utilisation. Therefore, in this study, roller-compacted rubbercrete (RCR) was produced by partially replacing fine aggregate with CR. Nano silica was used as an additive to cement to mitigate the loss of mechanical properties in RCR caused by incorporation of CR. The non-destructive tests, that is, rebound hammer test and ultrasonic pulse velocity (UPV) were used to evaluate the performance of RCR. Response surface methodology was then used to develop models for predicting the 28 days UPV and rebound number (RN) of RCR. Combined UPV–RN (SonReb) models for predicting the 28 days strength of RCR based on combining UPV and RN were developed using multivariable regression (double power, bilinear, and double exponential models). From the combined SonReb models formulated, it is concluded that the double exponential model has better accuracy for predicting the 28 days compressive strength of RCR compared to the double power models recommended by RILEM 43-CND for conventional concrete.

In this study, the influence of the orientation of embedded piezoelectric ceramic lead zirconium titanate (PZT) on the mechanical performance of hybrid fiber-reinforced (polypropylene and glass fiber) concrete beams was evaluated. The performance of concrete was evaluated under self-weight, followed by assessing the mechanical property using the electromechanical impedance (EMI) technique after optimization of M30 grade concrete with polypropylene fiber and glass fiber. PZT patches are embedded at different orientations, i.e., 0 deg, 45 deg, and 90 deg, with the axis of the structure for monitoring the hydration of the RC beam. The change in stiffness due to heat hydration in the concrete structure after 5, 7, 14, 21, and 28 days was observed by curing hybrid concrete beams and examining them after 5, 7, 14, 21, and 28 days. On the fifth day, beams were simply supported and allowed to deflect under their weight, and measurements of heat hydration in terms of conductance at frequencies ranging between 1 and 1000 kHz were done. Similarly, days 7, 14, 21, and 28 were done. Day 5 was considered the baseline. It is noted that the PZT sensor placed at an angle of 45 deg is the least effective in recording the incremental changes in hydration that occurred in the concrete beam. The highest quality results were obtained at 90 deg, which is further demonstrated by statistically quantifying the changes using the root-mean-square deviation (RMSD) percentage method and proves to be the most optimized orientation to obtain the stiffness of the hybrid reinforced beam in terms of conductance.

The major problems related to roller compacted concrete (RCC) pavement are high rigidity, lower tensile strength which causes a tendency of cracking due to thermal or plastic shrinkage, flexural and fatigue loads. Furthermore, RCC pavement does not support the use of dowel bars or reinforcement due to the way it is placed and compacted, these also aided in cracking and consequently increased maintenance cost. To address these issues, high volume fly ash (HVFA) RCC pavement was developed by partially replacing 50% cement by volume with fly ash. Crumb rubber was used as a partial replacement to fine aggregate in HVFA RCC pavement at 0%, 10%, 20%, and 30% replacement by volume. Nano silica was added at 0%, 1%, 2% and 3% by weight of cementitious materials to improve early strength development in HVFA RCC pavement and mitigate the loss of strength due to the incorporation of crumb rubber. The nondestructive technique using the rebound hammer test (RHT) and ultrasonic pulse velocity (UPV) were used to evaluate the effect of crumb rubber and nano silica on the performance of HVFA RCC pavement. The results showed that the use of HVFA as cement replacement decreases both the unit weight, compressive strength, rebound number (RN). Furthermore, the unit weight, compressive strength, RN, UPV and dynamic modulus of elasticity of HVFA RCC pavement all decreases with increase in crumb rubber content and increases with the addition of nano-silica. Combined UPV-RN (SonReb) models for predicting the 28 days strength of HVFA RCC pavement based on combining UPV and RN were developed using multivariable regression (double power, bilinear, and double exponential models). The exponential combined SonReb model is the most suitable for predicting the compressive strength of HVFA RCC pavement using UPV and RN as the independent variable with better predicting ability, higher correlation compared to the single variable models.

In this study, different types of plasticizers were used to investigate their effects on the fresh and hardened properties of high calcium fly ash geopolymers (HCFA). Modified polycarboxylate polymers (G3) and lignin-based polymers (G1) were used as plasticizing admixtures and the results were compared to the effect of tap water addition. The results showed that all the admixtures used are effective in increasing the workability of the HCFA geopolymers mixtures and the workability increased by 25-48% compared to the control mixtures. However, the use of G3 has adversely affected the strength by a reduction of 20%. While the use of G1 reduced the final setting time by 7% which is critical in the case of HCFA geopolymers where the final setting time occurs within 70 minutes. Water can be considered as the best admixture in terms of cost, setting time, and effect on compressive strength and it can be used where medium workability enhancement is required.

Geopolymer system is new binding materials in concrete industry that is produced by the alkaline solution and materials rich in aluminosilicate such as fly ash. The effect of the alkaline solution to fly ash ratios of 0.3, 0.4 and 0.5 on mortar geopolymer properties was an issue in this study. The results showed that the higher alkaline solution to fly ash ratio improves the workability and brings a longer setting time, whereas the lower alkaline solution to fly ash ratio gains the significant compressive strength. It was a similar pattern with conventional mortar used ordinary Portland cement, which the compressive strength at 7 days was 85%-90% for 28 days compressive strength, whereas conventional mortar is only 65%-75%. This was due to the higher reactivity in geopolymer system that was faster than the pozzolanic reaction.

There is a need in enhancing high-density concrete (HDC) for safeguarding sub-sea pipelines and constructing concrete mattresses for pipeline stabilization. To tackle these issues, a novel approach using a combination of supplementary cementitious materials like fly ash (FA) and graphene oxide (GO) have been successfully used in the partial replacement of the cement in this study. This research aims to enhance density, water resistance, and compressive strength properties for offshore applications by using GO and FA. A central composite design (CCD) of the response surface methodology (RSM) was employed, generating thirteen mixes with varying dosages of GO in the range of 0.013%–0.053% by weight of the cement and FA in the range of 20%–50% by weight of the cement. The HDC mixes exhibited enhanced characteristics, including an increased density of 4282 kg/m³, a maximum compressive strength of 37.9 MPa, and reduced water absorption at 2.52%. Response predicted models were established and validated through ANOVA, and multi-objective optimization was performed at a desirability of 58%. This yielded optimal GO and FA dosages of 0.013% and 37.87% respectively, for HDC with improved performance. The R2values for the models range from 70% to 96%, showing a good level of the model quality. The findings present promising opportunities for more sustainable, cost-effective, and environmentally friendly HDC solutions for offshore applications.

Graphene oxide (GO) is a 2D nanoparticle with dimensions less than 100 nm and acts as nano reinforcement in cementitious composites as a filling, crack-arresting agent, and nuclei for cement hydration. GO can be utilized to improve the microstructure and mechanical properties in a variety of construction and building technology applications. Through a coherent, comprehensive mixed reviewing method, this study seeks to evaluate the research efforts on utilizing GO in cementitious composites and map the research viewpoints from available literature (bibliometric analysis and systematic review). A total of 1437 publications were screened in which 59 articles were selected upon relevancy. Bibliometric mapping is used for keyword occurrence and the tested properties of cementitious composites containing GO. The review finds that the advantage of GO as a reinforcement in cement composite is that it is more effective in controlling crack development and propagation at the nano scale level in contrast to conventional reinforcement. The use of GO in cementitious composites offers many interesting paths and provides a foundation for further optimization in concrete, mortar, engineered cementitious composites, and cement paste. On the other hand, this use has a negative influence on various features of each type of reviewed material. More research is needed to gain a better knowledge of the long-term effects of the mechanical properties and durability of GO-based cementitious composites to promote their wider use in diverse applications in the construction sector.

Steel slag waste is a by-product of steel mining industry. Effort to utilize the steel slag in concrete production has been failed due to its high contents of MgO which causes volumetric instability of the hardened concrete. Researchers also have failed to utilize the steel slag in the sub-base of road construction due to its low compaction ratio. Geopolymer concrete is a new sustainable material made of mainly two materials which are alkali liquid and source material. The source material usually has to be pozzolanic. However, the chemical composition of the steel slag has shown that the steel slag is not considered as a pozzolanic in accordance to the requirement of the ASTM. Therefore, a special modification has been carried on and a geopolymer steel slag brick has been developed. The new developed geopolymer steel slag brick has compressive strength of about 10 MPa which is made the brick suitable for construction of a load bearing walls.

Rubbercrete is a concrete containing crumb rubber as partial replacement to fine aggregate. Advantages of rubbercrete have been reported by many researchers. In contrast to normal concrete, rubbercrete is a more ductile which can be used in areas prone to earthquake. In this paper seven reinforced rubbercrete beams without shear reinforcement are fabricated and tested up to failure. Three parameters are considered: beam width, effective depth and a/d. The experimental results are then compared with available shear quations. Available shear quations have produced conservative shear stress prediction for the reinforced rubbercrete beams.

This research is to investigate the properties of compressed building bricks producedfrom Cameron Highlands reservoir sediment. The particle size distribution of the sediments are graded as silt and sand. The sediments used were as total replacement of the normal soils used in the compressed soil bricks. This paper presents the compilation of experimental brick properties; compressive strength, water absorption, microstructure and heavy metal leachingof the compressed sediment bricks. The experimental results shows that increasing use of reservoir sediments decrease the compressive strength andincrease the water absorption. The heavy metal concentrations of the leachates from the leaching test are all within the regulatory limits. The optimum mix is derives from the compressive strength and the water absorption in which in this research is Mix 4, 70% sedimenta, 20% sedimentb and 10% cement,complying with ASTM C129 – Non Load Bearing Bricks [1].

In some cases a cut-out web opening in a reinforced concrete (RC) beam is required to facilitate the passage of electrical and mechanical pipes and ducting from one side to another. The presence of cut-out web openings will lead to decreasing in the load carrying capacity of these RC beams. Therefore, strengthening the vicinity of these openings by using Carbon Fiber Reinforced Polymer (CFRP) will represent the best practical solution. In this study, thirteen RC beams with different sizes of cut-out web openings and with different layers of CFRP strengthening and also one solid RC beam (control) were prepared and tested to failure. The outcome of this experimental and analytical study showed that the modified Eurocode 2 model can reasonably be used in computing the shear forces of RC beams having the vicinity of their cut-out web openings strengthened with single/multi layers of CFRP. In addition, for safe design purposes, a reduction factor has been suggested as well.

The aim of the research is to develop engineered cementitious composite mixtures satisfying the self-compacting concrete requirements and to evaluate the hardened properties of self-compacted ECC mixtures. To enhance the concrete performance, PVA is used. The PVA improved some characteristics and properties of the concrete. Ten mixes with different Polyvinyl Alcohol (PVA) fiber contents (0.0%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5% and 5.0%) have been prepared. Three cubes (100mm x 100mm x 100mm), three beams (100mm x 100mm x 500mm) and three cylinders (150mm diameter and 300mm height) have been cast for each mix and tested at the age of 7 and 28 days for compressive strength and at age of 28 days for splitting and flexural strength. The V-funnel, L-box and slump test also have been conducted to access the fresh properties like workability and flowability of the concrete. The results indicated the increase in the strength of the concrete and the formulas for predicting the compressive, splitting and flexural strength from PVA (%) has been developed.

The urgent need for a web opening in the pretensioned inverted T-beams after the construction for essential services causes local cracking around the opening which leads to decrease in stiffness and load carrying capacity. Therefore, strengthening the vicinity of the opening is essential to restore the loss in load carrying capacity of the beam using GFRP. To study the deflection of pretentioned inverted T-beam with web opening, three-dimensional finite element beam models are developed before and after GFRP strengthening using the finite element analysis (FEA). Modeling methodology and nonlinear analysis approach in ANSYS are presented. The results obtained from the FEA beam model are compared with the test data in terms of load-deflection curve. It has been concluded that FEA models are good representations for GFRP strengthened beams with web openings in terms of the number of elements, structural details, and, especially, reasonably accurate results in general.

The objective of this research is to investigate the potential use of Cameron Highland reservoir sediment in compressed brick production. The sediments can be classified as well-graded clayey sandy SILT and well-graded gravely SAND whereby the grain size is comparable to the grain size of sand and silt. The sediment was used as a 100 % replacement for the soils content in conventional soil cement bricks. Besides that, sodium bentonite, mica, fly ash and bottom ash are used as pozzolan to partially replace the cement in the sediment cement bricks. This paper presents the compressive strength of sediment cement brick incorporating sodium bentonite, mica, bottom ash and fly ash as partial replacement of cement. The total replacement of soils by Cameron Highland reservoir sediment (Mix 2) shows significant increase in compressive strength of the bricks compare to the conventional soil cement bricks (Mix 1), while partial replacement of 10 % pozzolan results in optimum strength. On the other hand, 10 % of bottom ash and 10 % of fly ash (Mix 13) as partial replacement of cement achieved the highest compressive strength. This implies that sodium bentonite, mica, fly ash and bottom ash can be used as pozzolan to partial replace the cement.

This paper presents the results of a research project aimed at providing standard circular web openings to the popular precast pretensioned inverted T-beam. Opening diameter and placement and required materials strengths were investigated. In this paper, the non-linear analysis, interaction diagram and deflection response surface plot of simply supported pretensioned inverted T-beam with circular web openings are presented. Two design parameters are varied that is: opening location and numbers of openings. The results from non-linear finite element analysis were substantiated by test results from five pretensioned inverted T-beams with web opening and one solid beam. Good agreement is shown between the theoretical and the experimental results. The effect of openings on the behaviour of such beams at different stages of loading are presented. The test results obtained from this investigation show that the performance of the specimens with web openings was almost identical to that of the specimen without web openings. An algorithm which is written to plot interaction diagram for estimating the cracking load is proposed. Deflection response surface plots using general factorial design are also presented.

This paper presents the findings of an investigation on the impact resistance of graphene oxide (GO) modified rubberized engineered cementitious composite (GOCRECC) and the development of response-predictive models and optimization using response surface methodology (RSM). The input factors considered as the independent variables were the GO at 0, 0.02, 0.04, 0.06 and 0.08% addition by cement weight and crumb rubber (CR) at 1, 3 and 5% replacement of fine aggregate. Fifteen mixes having different quantities of input factors were used for the determination of the initial (E1) and ultimate (E2) impact energy using the ACI 544. R drop weight impact test method. The results showed that impact resistance of the GOCRECC mixes increased with increasing contents of the input factors. Response predictive models for E1 and E2 were developed and found to have high R2values of 78 and 93% respectively, after validation using the analysis of variance (ANOVA). The optimization performed yielded an optimal amounts of the input factors of 0.0347 and 5% for GO and CR respectively at a desirability value of 74%.

Engineered cementitious composite (ECC) requires a lot of material tailoring for the desired self-compacting properties at fresh state and controlled crack width with strain hardening behavior at hardened state to be attained. Finding a balance between these two important stages (fresh and hardened) of the composite without compromise on any of the desirable properties is not an easy task. This research was aimed at utilizing the technique of multi-objective optimization in trying to determine an optimal Polyvinyl alcohol (PVA) fiber volume fraction and HVFA replacement of cement (two of the most important ingredients of ECC) to develop a self-compacting HVFA-ECC (SC-HVFA-ECC) with desirable properties at both fresh and hardened stages without compromise. Using the central composite design (CCD) of RSM, 13 mixes of varying combinations of the input factors (PVA: 1–1.5 %, FA: 50–70 %) were developed on which six responses (fresh state: v-funnel time, T500and slump flow; hardened state: compressive strength, flexural strength and tensile capacity) were investigated. Six response models (5 quadratic and 1 linear) were successfully developed and validated using ANOVA. All the models turned out to have a very high R2value ranging from 87 to 97 %. The multi-objective optimization yielded optimal values of the variables (PVA: 1.67 % and FA: 53.61 %) and predicted optimized values for the responses. The predicted values were experimentally validated and found to compare very well with the experimental values at less than 5 % error.

Researchers have used crumb rubber in the manufacturing of engineered cementitious composites (ECC) as a solution for spalling, however, it reduces the mechanical and physical properties. Therefore, this research reviews the available and related literature reviews on rubberized ECC and its constituent. The role of each constituent in a rubberized ECC mix is also reviewed. It’s concluded that utilizing rubberized ECC helps to solve environmental issues relating to improper disposal of tyres. As a result, fly ash has been the most common substance utilized in rubberized ECC by scholars all over the world over the past years because of its encouraging impacts on rheology, matrix toughness control, and interactive effect between fiber and matrix. It’s also found that the rectification of the crumb rubber drawbacks in ECC is by incorporating a modern method of adopting nano-silica, Polyvinyl alcohol (PVA) fibers, graphene oxide into the rubberized ECC mixes. Therefore, rubberized ECC can be utilized for civil engineering applications, especially with the inclusion of nano-silica and graphene oxide, as a result of its high ductility and low permeability.

•The shear span-depth ratio less than 2.5 can localize effect of shear failure of DEBs.•Variation of the DEBs scheme lead to discrepancy of the failure load capacity between the PCI analysis with the test results.•PCI code has not yet accommodated the use of concrete/composites other than the lightweight or normal weight concrete.•The empirical equations specified in PCI code is more intended for design of dapped-end reinforcements.

Multi-layers of carbon fibre reinforced polymer (CFRP) were used to strengthen engineered cementitious composites (ECC) to study their effects on flexural and tensile strengths. Response Surface Methodology RSM was used to obtain the number of trial mixes. A total of 13 mix designs were suggested with two variables: polyvinyl alcohol (PVA) fibre (0.5 %, 1.25 % and 2.0 %) and number of CFRP (1, 3 and 5 layers). The result showed that the flexural strength of specimens with 0.5 % and 2.0 % PVA fibre was enhanced by more than 40 % and 55 %, respectively, when the CFRP layers were increased to 3 and 5 layers, which subsequently increased the absorption energy of the specimens by more than 20 %. Moreover, the tensile strength of the specimens with 1.25 % and 2.0 % PVA fibre improved by 31 % and 61 %, respectively, after these have been strengthened with 3 and 5 CFRP layers. To validate these results, the experimental responses were analysed and optimised using RSM. The coefficient of determination R2yielded high values at 0.9647 and 0.9747, which indicated the good agreement of the proposed model to the experimental responses. Consequently, a quadratic model and a 2FI (two-factor interaction) model were developed to estimate the bond behaviour of CFRP-strengthened ECC. Based on these models, the best solution of CFRP strengthening with respect to the present study is to use 2 % PVA fibre and 5 layers of CFRP.

Since the mid-2000s, the transformation for the advanced 21st-century construction material has been on a headway utilizing the cutting-edge nanomaterials includes nano-silica, Carbon Nanotubes (CNTs), and Graphene Oxide (GO). GO is a recently invented only 2D carbon-based nanomaterial as it provides an additional dimension for the reactivity with cement composites. GO is an irresistible nanomaterial as it reforms the cement composite ranging from the atomic scale to macroscale and strengthens the mechanical properties (viz., compressive strength, tensile strength, flexural strength, and Young's modulus), durability and other multifunctional behavior. The availability of larger surface area and various oxygen-based functional groups form a linkage and contributes to the impressive behavior of the cementitious matrix. This research article presents a comprehensive review of the performance and behavior of cementitious composites tailored with GO nanomaterial.

Evaluation of the effects of nano-silica amount and superplasticizer (SP) dosage on the compressive strength, porosity and slump flow on high-volume fly ash self-consolidating mortar was investigated. Multiobjective optimisation technique using Design-Expert software was applied to obtain solution based on desirability function that simultaneously optimises the variables and the responses. A desirability function of 0.811 gives the optimised solution. The experimental and predicted results showed minimal errors in all the measured responses.

This paper investigated the possibility of using crumb rubber as partial replacement to fine aggregate in roller compacted concrete for pavement applications where fine aggregate was replaced with crumb rubber at 0%, 10%, 20% and 30% to produce roller compacted rubbercrete (RCR). In order to achieve a combined aggregate gradation similar to the one recommended by ACI 211.3R and US Army Corps of Engineers method, fly ash was used as mineral filler. Several trials were done to achieve the combined grading, and finally a combination of 55% fine aggregate, 40% coarse aggregate and 5% fly ash as mineral filler was used. Silica fume was then used as mineral filler instead of fly ash and the fresh density and compressive strength were compared. A target flexural strength of 4.5 MPa and the mix design was developed using the geotechnical concept according to ACI 211.3R/CRD-C161-92. The Results showed that fresh density and compressive strength decreases with increase in partial replacement of fine aggregate with crumb rubber. RCR containing silica fume showed lower fresh density and higher compressive strengths than that with fly ash. However, all the mixes achieved a strength higher than the design target strength at 28 days except for 30% crumb rubber containing fly ash mineral filler, while 10% crumb rubber achieved target strength even at 3 and 7 days for silica fume and fly ash.