•Thermal insulating mortars were exposed to different accelerated ageing procedures.•Ageing tests included elevated temperature, freeze–thaw and elevated relative humidity levels.•The ageing ...procedures were designed to be equivalent to 10 years of natural ageing.•The long-term thermal conductivity and mould susceptibility of the mortars are assessed.•A maximum increase of thermal conductivity up to 30% is obtained after ageing.
The use of thermal insulation materials in the opaque walls is one of the best strategies toward the improvement of the thermal performance of the building envelope, thereby contributing to increase the energy efficiency of the built environment. In this context, an increasing number of studies are focusing on the development of mortars with enhanced thermal performance, i.e., thermal insulating mortars. However, considering the innovative character of these materials, reliable data on their long-term performance is still lacking, particularly concerning the thermal performance and suitability to refurbishment works. The aim of this paper is to evaluate the long-term thermal conductivity and biological colonisation of industrially produced and experimentally designed thermal mortars with EPS, cork and silica aerogel aggregates. The long-term performance of the mortars was assessed prior, during and after exposure to three accelerated ageing tests including elevated temperature, freeze–thaw cycles and high humidity levels. For each test, an empirical model (i.e., Arrhenius law, Peck model, and Coffin-Manson equation) was used to compute the acceleration factor, thus allowing to correlate the accelerated and natural ageing results and to estimate the degradation levels that would be obtained after 10 years of exposure to natural weather conditions. The results of the thermal conductivity show that a maximum increase of 10 % and 30 % can be obtained after ageing for the industrially produced and experimentally designed mortars, respectively. Moreover, all mortars were susceptible to mould growth, with the greatest biological colonisation levels obtained after the high moisture content ageing for the experimentally designed mortars.
Highly sulfonated carbon nano-onions (SP–CNOs) with large specific surface area are used as a new type of nanofiller in sulfonated poly(arylene ether sulfone) (SPAES) to construct and adjust the ...proton transfer channels efficiently. SP-CNOs are synthesized from nanometer diamonds via thermal annealing, phenylation and sulfonation, and characterized by XRD, XPS, BET, Raman and HRTEM. The obtained mesoporous SP-CNOs possess a large specific surface of 350 m2/g and an average pore size of 9.7 nm, which endow the nanoparticles with good dispersivity and hydrophilicity. A series of composite membranes based on SP-CNOs/SPAES are prepared through the solution casting approach and evaluated by FESEM, XRD, TGA, water uptake, proton conductivity, chemical stability and fuel cell performance. The results indicate that the composite membranes all show excellent mechanical toughness and greatly enhanced water-retention capacity, thermal, dimensional and oxidative stability due to the good interfacial compatibility and the formation of hydrogen-bond interaction between SP-CNOs and SPAES. The SPAES/SP-CNOs-1.5 membrane achieves the highest proton conductivity of 181.2 mS/cm at 90 °C, which is 45% higher than that of SPAES; H2/O2 fuel cell performance records a power density of 735 mW/cm2 at 80 °C, which is slightly better than that of Nafion® 112. In addition, the SPAES/SP-CNOs-1.5 membrane undergoes the CV decay of 0.38 mV/h after 168 h at 80 °C, which is comparable to Nafion® 112 (0.43 mV/h) but lower than that for the pristine SPAES membrane (0.54 mV/h). After the accelerated stress test, the SPAES/SP-CNOs-1.5 membrane exhibits superior cell performance and lower hydrogen crossover than the pristine SPAES membrane.
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•Highly sulfonated carbon nanon-onions (SP–CNOs) were synthesized.•SP-CNOs enhanced water retention and proton conductivity of the composite PEMs.•The composite PEMs showed prominent mechanical and antioxidative stabilities.•0D SP-CNOs was a promising candidate for the constructing long-range H+-channels.•The composite PEMs displayed high fuel cell performance and durability.
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•Heating values of rapeseed oil methyl esters were decreased of 3.45 % past deterioration at room temperature for 20 years.•The acid number of diesel oil increased by 75% as a result ...of natural deterioration.•The rapeseed oil methyl ester, stored in room conditions for 20 years, showed a change in colour on a colour analysis.•Density and kinematic viscosity were very closely related to the global color measure, while heating value had significant.•The rapeseed oil methyl ester is suitable for long-term storage and can be used as a fuel.
The article discusses the results of research into properties of rapeseed oil methyl esters of and diesel oil subjected to deterioration process at room temperature for 20 years. The heat of combustion and heating values have been measured in laboratory conditions using an automatic calorimeter. The results show a slight decline in energy properties, with a change of 3.45 % on average. An image analysis has been used to evaluate the effects of ageing and combustion quality to compare the two fuels. The main purpose of research on rapeseed oil methyl esters in relation to diesel oil was to determine the energy properties of the tested fuels, i.e., the heat of combustion and the heating value. The side aims of research were to determine selected functional properties of the tested fuels.
Changes in density, kinematic viscosity, acid value and water content at the beginning and end of the experiment have also been examined. Deposits formed after combustion in a calorimetric bomb in crucibles and on the injector nozzles in a self-ignition engine have been examined with the use of the weight method and images analysis.
After a long period of storage, density, and acid number of rapeseed oil methyl esters have been slightly changed, while kinematic viscosity and water content increased significantly to exceed the limit values. The acid value of diesel oil increased by 75% as a result of natural deterioration.
•A machine learning aided chemophysical modelling method is developed.•A novel support vector regression algorithm named X-SVR is implemented.•Both the material and environmental uncertainties are ...taken into consideration.•Stochastic durability and safety analyses on building composites are performed.•The proposed method is demonstrated to be stable, accurate and efficient.
The adverse impacts of material deterioration on structural durability and human safety have become increasingly recognised. This paper is concerned with novel metamodeling on the degradation of cementitious composites and structures under environmental attacks. The material deterioration represents a chemophysical process, consisting of the reactive transportations of multiple species. Various coupling effects and associated uncertainties, both material and environmental, may be involved, leading to a complex stochastic system that can only be solved by Monte Carlo simulation. The computational intensiveness calls for advanced methods for uncertainty quantifications. In this paper, an eXtended support vector regression (X-SVR) method is developed to achieve the high-fidelity and efficient stochastic chemophysical modelling. The advanced performance of the proposed method is explored by modelling a laboratory test and a real-life engineering structure.
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•Varying dosages/lengths of Jute fibers (JFs) are incorporated in adobe mixtures (AMs).•Negatively, high JF dosages increase the capillary water absorption of AMs.•JFs do not affect ...the compressive and flexural strength of AMs.•JFs improve the thermal/cracking control/toughness/water erosion performance of AMs.•The combination of 2.0 wt%-15 mm JFs presents the best performance among AMs.
Due to their sustainability as well as physical and mechanical performance, different natural fibers, both vegetal and animal fibers, have been successfully used in adobe mixtures (AMs) to enhance properties such as cracking control, flexural toughness and water erosion resistance, among others. However, the use of jute fibers (JFs), one of the most largely produced vegetal fiber worldwide, has not been extensively studied on AMs. Consequently, this study evaluates the effects of the incorporation of varying dosages (0.5 and 2.0 wt%) and lengths (7, 15, and 30 mm) of JFs on the physical/thermal/mechanical/fracture and durability performance of AMs, a specific type of earth-based construction material widely used globally. Experimental results showed that the incorporation of 2.0 wt% dosages of JFs increased the capillary water absorption of AMs, which might affect AM durability. The latter result could be explained by the additional porosity generated by the spaces left between the JFs and the matrix of adobe, as well as the inherent water absorption of the JFs. The incorporation of JFs significantly improved the behavior of AMs in terms of thermal conductivity, drying shrinkage cracking control, flexural toughness and water erosion performance, without affecting their compressive and flexural strength. For example, flexural toughness indices were increased by 297% and crack density ratio as well as water erosion depth values were reduced by 93% and 62%, respectively, when 2.0 wt%-15 mm length JFs were incorporated into AM. Since the latter combination of JF dosage and length provided the overall best results among AMs, it is recommended by this study as JF-reinforcement scheme for AMs for construction applications such as adobe masonry and earth plasters.
•The NTD EIS technique is used to assess the durability of LC3 binder against combined chloride sulfate penetration.•LC3 technology improves the durability performance of reinforced concrete ...structures in simulated real-life conditions chloride-sulfate penetration.•LC3 achieved the same compressive strength as traditional OPC.•The excellent resistance of LC3 against the combined chloride-sulfate attack is attributed to the CH consumption, matrix densification, and the filler effect generated by the ternary reaction of ternary LC3 binder.
Concrete technology has significantly advanced towards alternative sustainable and eco-friendly cement-based materials. Accordingly, the durability of real-life blended concrete under realistic exposure aggressive conditions needs to be explored in depth. This study evaluates the effect of local raw clay on the durability performance of underground reinforced concrete in a simulated real-life aggressive environment with combined chloride-sulfate attack. Blended limestone cement (LC) containing calcined clay (LC3) or fly ash (LCF) with 40% replacement by cement mass, were prepared concurrently to compare the results with the traditional OPC. Assessment of durability performance of reinforced blended concrete was performed using non-destructive electrochemical impedance spectroscopy technique (EIS), and compressive strength. Characterization and elaboration of electrochemical phases were monitored by X-ray diffraction (XRD), thermo-gravimetric analysis (TGA), and SEM/EDS analysis. Electrochemical measurements showed that the diameter of the impedance semi-circle in both high and low-frequency regions of LC3-based reinforced concrete increases as corrosion progresses, while that of LCF and OPC decreases. LC3 showed the best corrosion resistance marked by a lower corrosion rate and comparable strength. Furthermore, LC3 binder exhibited a good hydration degree, with higher CH and Friedel’s salt content. Ultimately, the LC3 technology improves the durability performance of reinforced concrete structures in simulated real-life conditions which could advance its application on the industrial scale.
•A dynamic Bayesian network-based durability assessment framework is developed;•Time-varying environment and 2D chloride ingress are considered in durability assessment;•A novel computation method of ...conditional probability table calculation is proposed;•A real-world example is employed for the durability assessment of RC beams.
Reinforced concrete (RC) structures under the marine environment may be subjected to chloride-induced corrosion of reinforcement, which significantly impacts the structural serviceability and reliability and further affects the sustainability and development of society. However, most of the existing durability assessment methods for RC structures only address their static and deterministic durability prediction and assessment at the design stage given the constant environment, ignoring the influences of stochastic environmental effects, uncertainties in structural properties, and inspection results. To this end, this paper proposes a dynamic Bayesian network (DBN) based durability assessment framework combined with a deterioration model that considers random changes in environmental parameters, convective chloride ion transport, and corrosion-induced cracking of concrete. In this framework, two-dimensional chloride transport and its influences on the durability deterioration assessment are concerned and achieved using the finite difference method. Besides, to reduce the deviations in probabilistic evaluation, the good-lattice-point-set-partially stratified-sampling (GLP-PSS) method is employed to establish a DBN framework. The proposed DBN framework is used for sensitivity analysis through a real-world example to examine the effects of the environmental model, chloride transport mode, and inspection results of concrete crack on durability assessment.
•Non-destructive tests are used to characterise earthen mortars in masonry joints.•Durability and mechanical properties of earth-based mortars are assessed on-site.•Penetrometer, Schmidt hammer, ...pendulum hammer and scratch tests are evaluated.•Reliability and limitations of NDTs for characterising earth-based mortars are identified.•Six qualitative indicators to compare the performance and feasibility of NDTs are defined.
In this paper, the use of non-destructive tests for the mechanical characterisation of earth-based mortars in masonry joints is discussed. Four testing methods, namely the penetrometer, Schmidt hammer, pendulum hammer and scratch test, originally developed for other types of mortar, are reviewed. The methods are applied to the earth-based mortars at the Wupatki Pueblo archaeological site, in Arizona, US. The outcomes of the experimental programme allowed to assess the reliability of the methods and to identify their limitations. Finally, the methods are compared in terms of six qualitative indicators, namely easy-of-use, consistency of results, range and granularity of results, respect towards cultural value, depth of investigation under the visible surface and versatility in application. Overall, the penetrometer test is recommended as the preferable method to characterise the mechanical performance of earth-based mortars.
