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•Five surface treatments of tyre crumbs yielded strength improvements of 27–56%.•Silica fume coating improves the adhesion between tyre crumbs and concrete foam.•A denser gel with ...lower Ca/Si was observed around crumbs for silica fume treatment.•Chemical treatments reduced water contact angle on rubber (increased hydrophilicity).•Sulfuric acid etched the crumbs and formed zinc sulphate crystals on the surface.
The uptake of recycled tyre crumb (RTC) in concrete can result in a significant loss of strength because of weak adhesion between cement and rubber. Five RTC surface treatment methods (cement coating, silica fume coating, sodium hydroxide, potassium permanganate and sulphuric acid soaking) were used to mitigate strength loss in concrete composite foam with RTC. All five methods yielded strength improvements between 27% and 56%, with sulphuric acid and silica fume coating having the largest improvement. Silica fume coating, a treatment method used for the first time, improves strength because of the better adhesion between RTC and mortar. In addition, the formation of low Ca/Si gels was observed at the rubber-mortar interface based on SEM-EDS analysis. A reduced water contact angle on rubber showed that the three soaking methods were able to successfully reduce the hydrophobicity of RTC. Microscopic analysis of sulphuric acid treated RTC revealed etching of the surface and possible formation of polar zinc sulphate crystals. Silica fume coating provides an economically feasible solution with less safety and environmental risks associated compared to the chemical treatments.
•Reviewed recent progress and directed future research for modular buildings.•Commonly used in UK, Sweden, Japan and USA with growing interest in Australia and China.•Prefabricated components have ...demonstrated satisfactory structural performance.•Uptake barriers are mainly related to the lack of logistical support.•Prefabricated modular buildings is the next generation of housing.
Modular construction offers faster and safer manufacturing, better predictability to completion time, superior quality, less workers on site, less resource wastage, and a more environmentally friendly solution than the conventional construction process. Despite having several advantages of modular construction, the private sector still relies heavily on the traditional on-site construction method. To understand the scientific reason behind this situation, this paper critically reviews the recent developments, performances, challenges and future opportunities of modular buildings. Modular constructions are extensively used for low-rise buildings and further attracts strong interest for multi-storey building structures. Prefabricated modules demonstrated satisfactory performance under static, dynamic impact, cyclic, seismic, blast, fire and long-term sustained loading, and offer environmental, economic and social benefits. The acceptance and application of modular construction will further spread with the development of design guidelines, more skilled workers, addressing handing and transportation difficulties, and the development of novel interlocking connections between modules. Recently, composite materials demonstrated high potential to manufacture prefabricated building modules. In Australia, it is expected that modular construction will increase from the current stage of 3% to 5–10% by year 2030.
Equivalent sandwich panels composed of auxetic and conventional honeycomb cores and metal facets are analysed and compared for their resistance performances against impulsive loadings. The dynamic ...behaviours of these structures are numerically investigated, taking into account the rate-dependent effects. The Johnson-Cook model is employed to describe the dynamic responses of the composite sandwiches subjected to high strain-rate loadings. Analytical models are derived correlating unit cell geometrical parameters and crushing strengths of the representative panels at different impact velocities. Parametric studies are conducted to evaluate the performances of different sandwich panel designs under impulsive loadings. In particular, transmitted reaction forces and maximum stresses on the protected structure are quantified for various design parameters including the geometrical factors and the effective Poisson’s ratios. A quarter of the panel is symmetrically modelled with shell elements and the CONWEP model is used to simulate the blast loading. Auxetic panels demonstrate interesting crushing behaviour, effectively adapting to the dynamic loading by progressively drawing material into the locally loaded zone to thereby enhance the impact resistance. Meanwhile, conventional honeycomb panels deform plastically without localised stiffness enhancement.
•The compressive and tensile strength of high-performance concrete (HPC) is a highly nonlinear function.•An expert system is proposed to predict the compressive and tensile strength of HPC.•The ...expert system is based on artificial neural network and modified firefly algorithm.•The proposed approach provides an efficient and accurate tool to predict and design HPC.•The system significantly reduces the amount of laboratory work required.
The compressive and tensile strength of high-performance concrete (HPC) is a highly nonlinear function of its constituents. The significance of expert frameworks for predicting the compressive and tensile strength of HPC is greatly distinguished in material technology. This study aims to develop an expert system based on the artificial neural network (ANN) model in association with a modified firefly algorithm (MFA). The ANN model is constructed from experimental data while MFA is used to optimize a set of initial weights and biases of ANN to improve the accuracy of this artificial intelligence technique. The accuracy of the proposed expert system is validated by comparing obtained results with those from the literature. The result indicates that the MFA-ANN hybrid system can obtain a better prediction of the high-performance concrete properties. The MFA-ANN is also much faster at solving problems. Therefore, the proposed approach can provide an efficient and accurate tool to predict and design HPC.
In this study, a new hybrid model, namely the Electromagnetism-based Firefly Algorithm - Artificial Neural Network (EFA-ANN), is proposed to forecast the energy consumption in buildings. The model is ...applied to evaluate the heating load (HL) and cooling load (CL) using two given datasets. Each dataset was obtained by monitoring the effect of the façade system and dimensions of the building, respectively, on energy consumption. The performance of EFA-ANN is validated by comparing the obtained results with other methods. It is shown that EFA-ANN provides a faster and more accurate prediction of HL and CL. A sensitivity analysis is performed to identify the impact of each input on the energy performance of the building. From the results of this study, it is evident that EFA-ANN can assist civil engineers and construction managers in the early designs of energy-efficient buildings.
•Early prediction of HL and CL in buildings can help to design energy-efficient buildings.•A hybrid model is proposed to predict the HL and CL in buildings.•The model is based on ANN model and EFA optimization method.•Two different datasets were used to validate the model.•The proposed approach can assist in the early stage of building design.
End-of-life waste tyres are known to have negative economic and environmental impacts due to the difficulty associated with their disposal and recycling. The use of recycled tyre crumb (RTC) as a ...component of construction materials has emerged as a potentially sustainable solution to this environmental issue. There exists extensive research covering the use of RTC as a filler in conventional concrete. However, there are very limited studies focused on insulation properties of RTC in lightweight cellular concrete (LCC) as a sustainable application that can add value to the final product. This study investigates the effects of different RTC contents on compressive strength, porosity, thermal conductivity, sound insulation and water permeability of LCC as an insulator. A rather homogeneous distribution of tyre crumbs within LCC structure was achieved. It has been found that LCC samples containing RTC are suitable as insulators because the sound and thermal insulation are improved as rubber content is increased compared to the sample with similar density but without RTC. The insulation properties of this product also come with the same total porosity and a significant reduction in the rate of water permeability compared to the sample without RTC. 3D restructuring of micro-CT scan images of this composite revealed the effects of tyre crumb on the total and local porosity of this composite. Despite the fact that addition of tyre crumb reduced the strength, surface treatment of crumb rubber with sodium hydroxide solution exhibited significant improvement in the compressive strength of LCC as the result of better physical bonding with hydrated cement proven by scanning electron microscopy (SEM) images and energy dispersive spectroscopy (EDS) analysis.
•LCC-RTC composite has shown excellent water, thermal and sound insulation properties.•LCC-RTC composite offers a sustainable and cleaner production of insulating panels.•3D micro-CT scan images provided significant insights towards porosity calculation.•Surface treatment of RTC with sodium hydroxide (NaOH) resulted in better binding.•NaOH-treated rubber partially compensates the strength loss by the addition of RTC.
Numerous studies have examined the changes in streamflow in the Mekong River Basin (MRB) using observations and hydrological modeling; however, there is a lack of integrated modeling studies that ...explicitly simulate the natural and human‐induced changes in flood dynamics over the entire basin. Here we simulate the river‐floodplain‐reservoir inundation dynamics over the MRB for 1979–2016 period using a newly integrated, high‐resolution (~5 km) river hydrodynamics‐reservoir operation model. The framework is based on the river‐floodplain hydrodynamic model CaMa‐Flood in which a new reservoir operation scheme is incorporated by including 86 existing MRB dams. The simulated flood extent is downscaled to a higher resolution (~90 m) to investigate fine‐scale inundation dynamics, and results are validated with ground‐ and satellite‐based observations. It is found that the historical variations in surface water storage have been governed primarily by climate variability; the impacts of dams on river‐floodplain hydrodynamics were marginal until 2009. However, results indicate that the dam impacts increased noticeably in 2010 when the basin‐wide storage capacity doubled due to the construction of new mega dams. Further, results suggest that the future flood dynamics in the MRB would be considerably different than in the past even without climate change and additional dams. However, it is also found that the impacts of dams can largely vary depending on reservoir operation strategies. This study is expected to provide the basis for high‐resolution river‐floodplain‐reservoir modeling for a holistic assessment of the impacts of dams and climate change on the floodpulse‐dependent hydro‐ecological systems in the MRB and other global regions.
Key Points
A high‐resolution model is presented for the integrated simulation of river‐floodplain‐reservoir inundation dynamics
Historical impacts of dams on the Mekong River flood dynamics are found to be marginal compared to that of climate variability
Potential future dam impacts on the Mekong flood dynamics could be largely different than today even under business‐as‐usual conditions
Experimental and numerical studies were conducted to investigate the effect of polyurea coatings on the blast resistance of mild steel plates. Square steel plates with and without polyurea coatings ...applied to the back surface were subjected to localised blast loading, both experimentally and numerically using ANSYS® AUTODYN®. Two coating thicknesses were considered which were chosen such that each of the plates had the same areal density of 4.7 g/cm2 over the test area. The residual deformations of the plates were measured after each event and found to increase with coating thickness. The transient deformations of the plates were captured using high speed video. The video revealed that the polyurea coatings de-bonded over a circular area, resulting in a hyperelastic extension of the polyurea and a maximum transient deformation approximately twice that of the bare steel plates. Close agreement was found between the experimental and numerical results for the residual deformations; however, the peak transient deformations were under-predicted in the numerical models. This lead to the development of new Mooney–Rivlin material model constants for the polyurea which gave improved results. It was found that a numerical bond strength of 80 MPa between the polyurea and the steel gave the closest match with the experimental results. Further numerical modelling which varied coating thickness and location found no coating solutions which deformed less than a bare steel plate of equivalent areal density.
► Experimental and numerical studies subjected polyurea-coated plates to blast. ► Bare steel plates deformed less than coated plates with equivalent areal density. ► High speed video revealed the polyurea coatings de-bonded during the events. ► Good agreement was found between models and experiments for residual deformation. ► We found no improved polyurea solutions by varying coating thickness/location.
•The first auxetic nails are designed, fabricated, and experimentally investigated.•The auxetic nails do not always exhibit superior mechanical performance to non-auxetic nails.•The surface roughness ...plays a significant role in the applications of auxetic nails.•Several criteria are proposed for the future design of auxetic nails.•Some disadvantages of auxetic materials are discussed.
Under uniaxial compression (tension), auxetic materials would shrink (expand) laterally. It has been speculated that the auxetic property could be used to design superior nails for easier push-in and harder pull-out. In this study, the first auxetic nails are designed, fabricated and experimentally investigated. Pine timber and medium-density fibreboard are selected as testing materials. The push-in and pull-out performance of auxetic and non-auxetic nails is compared by using two key parameters of the maximum compressive force and the maximum tensile force. It is found that the auxetic nails do not always exhibit superior mechanical performance to non-auxetic ones. Also, the small auxetic deformation of one typical designed auxetic nail is revealed by the experimentally validated finite element model. The experimental and numerical results illustrate the limitations of exploiting the auxetic property in the nail application. Some suggestions are provided for more effective designs of future auxetic nails.
•A computational optimization approach is proposed to support adaptive façade design.•Two case studies are used to validate the capacity of the proposed approach.•The effects of the adaptive façade ...system are analyzed and discussed.•The proposed approach could reduce energy consumption by 14.2–29.0%.•The study facilitates the exploration of next-generation adaptive façade concepts.
The energy consumption in buildings, which accounts for approximately one-third of the total energy used in the world, can be reduced significantly by employing adaptive façades. In this study, a computational optimization approach is proposed to enhance the energy efficiency of buildings based on the design of an adaptive façade system, which can adapt its thermal and visible transmittance for dynamically varying climatic conditions. The engine of the adaptive façade design approach is an automated optimization process, which combines the building energy simulation program (EnergyPlus) with an optimization technique through Eppy, a powerful Python toolkit. The modified firefly algorithm, an in-house optimization tool, is employed to design the adaptive façade system in this study. However, our proposed method is not tied to any particular optimization tool and does not impose any restrictions on a type of building. To this end, the capability of the proposed method for enhancing building energy efficiency is validated by two case studies, namely a typical single office room and a medium office building. We found that the proposed adaptive façade system can reduce the energy consumption by 14.9–29.0% and 14.2–22.3% for the first and second case study, respectively, compared to the static façades. These significant findings demonstrate the potential of adaptive façades to enhance the energy efficiency of buildings.
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