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This paper aims to assess the effects of chemically accelerated leaching on the physical and mechanical properties of aerial lime–cement mortars (LCMs).

Two aerial LCMs, differencing mainly in their calcium hydroxide content, were degraded by the use of an ammonium nitrate solution as a leaching agent. The leaching effects were studied by evaluating the rate of change in physical (sorptivity and mass loss) and mechanical (flexural and compressive strength) characteristics of aerial LCMs. To quantify the evolution and kinetics of degradation, the leached depth was then characterized at different levels of degradation by means of a phenolphthalein solution.

The experimental results showed that the dissolution of binder decreases the mass, alkalinity and strength of aerial LCMs but increases their sorptivity. A linear relationship was derived by plotting the values of leached depth against the square root of immersion time in an aggressive solution. It was found that the leached depth followed diffusion-controlled kinetics.

It was found that the global loss of compressive strength of aerial LCMs because of complete dissolution of calcium hydroxide can reach up to 80 per cent.

The multi-scale numerical simulation method, able to represent the complexity of the random structures and capture phase degradation, is an effective way to investigate the long-term behavior of concrete in service and bridges the gap between research on the material and on the structural level. However, the combined chemical-physical deterioration mechanisms of concrete remain a challenging task. The purpose of this paper is to investigate the degradation mechanism of concrete at the waterline in cold regions induced by combined calcium leaching and frost damage.

With the help of the NIST’s three-dimensional (3D) hydration model and the random aggregate model, realistic 3D representative volume elements (RVEs) of concrete at the micro-, the meso-, and the macro-scales can be reconstructed. The boundary problem method is introduced to compute the homogenized mechanical properties for both sound and damaged RVEs. According to the damage characteristics, the staggering method including a random dissolution model and a thermo-mechanical coupling model is developed to simulate the synergy deterioration effects of interacted calcium leaching and frost attacks. The coupled damage procedure for the frost damage process is based on the hydraulic pressure theory and the ice lens growth theory considering the relationship between the frozen temperature and the radius of the capillary pore. Finally, regarding calcium leaching as the leading role in actual engineering, the numerical methodology for combined leaching and frost damage on concrete property is proposed using a successive multi-scale method.

On the basis of available experimental data, this methodology is employed to explore the deterioration process. The results agree with the experimental ones to some extent, chemical leaching leads to the nucleation of some micro-cracks (i.e. damage), and consequently, to the decrease of the frost resistance.

It is demonstrated that the multi-scale numerical methodology can capture potential aging and deterioration evolution processes, and can give an insight into the macroscopic property degradation of concrete under long-term aggressive conditions.

In this paper, three research topics are presented referring to different aspects of multifield problems in civil engineering. The first example deals with long term behaviour of wood under multiaxial states of stress and the effect of moisture changes on the deformation behaviour of wood. The second example refers to the application of a three‐phase model for soils to the numerical simulation of dewatering of soils by means of compressed air. The soil is modelled as a three phase‐material, consisting of the deformable soil skeleton and the fluid phases – water and compressed air. The third example is concerned with computational durability mechanics of concrete structures. As a particular example of chemically corrosive mechanisms, the material degradation due to the dissolution of calcium and external loading is addressed.

Around the world, many structures are affected by pathological reactions between the concrete and the surrounding environment in which these structures are designed, these pathologies lead to compromise their serviceability. In this context, this paper aims to study the durability of concrete in different environments with non-destructive techniques, by studying its contamination by the aggressive agents’ penetration. And this, by evaluation of the influence of the durability indicator that is the absorption by immersion, on the mechanical properties (compressive strength, modulus of elasticity and damage), of specimens having undergone immersion/drying cycles, in different aggressive media (water, seawater and acids: sulfuric and acetic with a concentration of 5%).

Concrete specimens were manufactured in the laboratory, and then underwent immersion/drying cycles, in parallel, the weight gain of the specimens was carried out in the wet state after immersion and in the dry state after drying, and the ultrasonic speeds were also taken in a dry state. The results showed a decrease in the mechanical properties studied, namely, the compressive strength as well as the elastic properties (modulus of elasticity, damage) as a function of the increase in absorption, and that the weakest properties are those of test specimens submerged in water.

Non-destructive tests have shown that the parameters examined increase with the immersion/drying cycles, up to the fourth cycle. Beyond that, they drop gradually, and this is valid for four environments. This decline is due to the degradation of cement pastes exposed to water, seawater and acid attacks. This is explained by the greater or lesser dissolution of all the major elements making up the cementitious matrix (CSH, Ca(OH)2, CaO, SiO2, C3S, C2S, C3A, C2S) depending on the nature and concentration of the chemical substances evacuated. The results showed that the highest absorption rate and damage are those recorded for the specimen immersed in water, followed by that of the specimens immersed in acids, followed by that of the specimen immersed in sea water. The highest compressive strength and stiffness are those of the specimen immersed in sea water, followed by that immersed in acids, then in water.

The work developed aimed to study the durability of concrete, by addressing the study of the coupling absorption – mechanical characteristics of concrete, in different aggressive media (water, seawater and acids), to seek a relationship between these parameters. The tests provided are non-destructive tests, which consist of taking measures that do not damage the concrete. They allow indirect measurements of the mechanical properties of concrete as well as the monitoring of their evolution over time. They also allow having certain accuracy, because the measurements are taken at the same place.

The cementitious/chemical properties of the untreated CFA are dependent on the coal composition and previous burning conditions. The purpose of this paper is to investigate whether untreated CFA can efficiently reduce cement replacement and does not require further combustion treatment to be a viable cement replacement.

Two types of mixes: Type I concrete and PCFA (Type I and 30 per cent untreated CFA) concrete were batched and subjected to compressive strength tests and cyclic exposures of 5 per cent sodium sulphate (Na₂SO₄) and 5 per cent magnesium sulphate (MgSO₄), respectively.

PCFA mix was 41.1 and 35.21 per cent lower in strength compared to Type I at 28 and 56 days correspondingly. Continuous-sulphate-exposure resulted in slow but continued strength development for both mixes. However, the strengths of PCFA cubes exposed to cyclic sulphate and sulphate/magnesium salts continued to increase at a lower rate from their corresponding 28-day strength (rate of 18.7 per cent and strength 27.30 MPa in Na₂SO₄ and rate of 10.0 per cent and strength 25.30 MPa in MgSO₄) while Type I specimens subjected to the same exposure conditions experienced drastic reductions in strength (rate of −15.0 per cent and strength 33.21 MPa in Na₂SO₄ and rate of −23.4 per cent and strength 29.94 MPa in MgSO₄).

Results justify the need for additional tests essentially: at different percentage replacement of untreated CFA, fineness of materials, chloride environment and longer exposures, to address the cementitious properties of untreated CFA as cement replacement.

Treatment methods for fly ashes require undoubtedly additional resources, energy input and cost. This paper paves the way to define whether untreated CFA can be used as cement replacement in concrete.

Low-carbon concrete represents a new direction in mitigating the global warming effects caused by clinker manufacturing. Utilizing Saudi agro-industrial by-products as an alternative to cement is a key support in reducing clinker production and promoting innovation in infrastructure and circular economy concepts, toward decarbonization in the construction industry. The use of fly ash (FA) as a cement alternative has been researched and proven effective in enhancing the durability of FA-based concrete, especially at lower replacement levels. However, at higher replacement levels, a noticeable impediment in mechanical strength indicators limits the use of this material.

In this study, low-carbon concrete mixes were designed by replacing 50% of the cement with FA. Varying ratios of nano-sized glass powder (4 and 6% of cement weight) were used as nanomaterial additives to enhance the mechanical properties and durability of the designed concrete. In addition, a 10% of the mixing water was replaced with EMs dosage.

The results obtained showed a significant positive impact on resistance and durability properties when replacing 10% of the mixing water with effective microorganisms (EMs) broth and incorporating nanomaterial additives. The optimal mix ratios were those designed with 10% EMs and 4–6% nano-sized glass powder additives. However, it can be concluded that advancements in eco-friendly concrete additive technologies have made significant contributions to the development of sophisticated concrete varieties.

This study focused at developing nanomaterial additives from Saudi industrial wastes and at presenting a cost-effective and feasible solution for enhancing the properties of FA-based concrete. It has also been found that the inclusion of EMs contributes effectively to enhancing the concrete's resistance properties.

The purpose of this study is to perform comprehensive investigation to assess the mechanical properties of nano-modified ternary cement concrete blend. Nano silica (NS) (1%, 2% and 3%) and waste marble dust powder (MD) (5%, 10% and 15%) was incorporated as a fractional substitution of cement in the concrete matrix.

In this experimental study, 10 cementitious blends were prepared and tested for compressive strength, flexural strength, splitting tensile strength and static modulus of elasticity. The microstructural characteristics of these blends were also explored using a scanning electron microscope along with energy dispersive spectroscopy and X-ray reflection.

The results indicate an enhancement in mechanical properties and refinement in pore structure due to improved pozzolanic activities of NS and the filling effect of MD.

To the best of the authors’ knowledge, no study has reported the mechanical and microstructural behavior of concrete containing marble and NS.

The economic significance of corrosion is now being increasingly appreciated throughout a wide range of industry. In some industries corrosion must be controlled if the industry is to function. This is so particularly of the chemical process industries, but is not wholly true of civil engineering. Exposed steel structures such as bridges must be protected, but generally the possibility of structural weakness arising from corrosion has been allowed for in design by generous safety factors. This attitude has generally prevailed in that part of civil engineering known as foundation engineering.

This work aims to demonstrate the use of electrochemical chloride extraction (ECE) to remove chloride ions away from the steel rebar in chloride-contaminated mortar and to mitigate the corrosion of the embedded steel.

To simulate salt contamination in concrete, sodium chloride was added at 0.5 per cent by weight of cement in the fresh mortar featuring a water-to-cement ratio of 0.45. The ECE treatments were varied at two electrical current densities (1 and 5 A/m²), using two electrolytes (0.1M NaOH and 0.1M Na₃BO₃ solutions) and for two periods (2 and 4 weeks). The average free chloride concentration in cement mortars before and after ECE treatment was quantified using a customized chloride sensor, whereas the spatial distribution of relevant elements was obtained using energy-dispersive X-ray spectroscopy. The effect of ECE treatment on the electric resistivity of mortar and the corrosion resistance of steel rebar was investigated by electrochemical impedance spectroscopy and potentiodynamic polarization measurements, respectively.

The experimental results reveal that the ECE treatment was effective in removing chlorides and in improving electric resistivity and compressive strength of the mortar, when using the sodium borate solution as the electrolyte. In this case, a 4-week ECE treatment at 1 A/m² decreased the free chloride content in the mortar by 70 per cent, significantly increased the Ca/Si ratio in the mortar near rebar, led to a more refined and less permeable microstructure of the mortar and significantly improved its compressive strength. The ECE treatment was able to halt the chloride-induced corrosion of steel rebar by passivation. A 4-week ECE treatment at 1 A/m² using sodium hydroxide and sodium borate solutions decreased the corrosion rate of rebar by 36 and 34 per cent, respectively.

This electrochemical rehabilitation of steel-reinforced concrete under chloride-contaminated condition is very effective in prolonging its service life.

This study aims to examine whether or not residential properties closer to landfill sites have lower offer values by the developers. That is, by analyzing real estate data and landfill site locations, the study seeks to provide insights into whether properties situated closer to landfill sites tend to have a lower offer values than those located farther away.

The study is exploratory in nature, and a case study approach is applied. A landfill site named “Uruli Devachi” is selected in the region of Pune district, and data is collected from 102 developers selling residential projects within a radius of 15 km (about 9.32 mi). The gathered data is analyzed by using basic descriptive statistics, one-way ANOVA and ordinary least squares (OLS) regression. The OLS regression helps to determine whether there is a relationship between the distance of a residential property from a landfill site and its offer value.

The findings suggest that landfill sites have a detrimental impact on residential property offer values, with the negative impact increasing with proximity to a landfill site. The negative effect seems to vanish after over 10 km (about 6.21 mi). The developers provide extra facilities including a clubhouse, a children’s play area, a gym and a swimming pool in an effort to mitigate the negative effects of the landfill site on residential properties.

The findings of this study could have implications for property developers, real estate professionals and policymakers in understanding how landfill proximity might impact property offer values.

This study presents many novelties for the Indian housing market: the landfill sites do have a negative effect on the offer value of residential property; the closer the residential property to a landfill site, the higher the negative effect. Further, the developers try and mitigate the negative effect of landfill sites on residential properties by providing additional amenities such as a clubhouse, children’s play park, gym and swimming pool.