The goal of this study was to determine the coefficient of permeability as well as the rate of carbonation of concrete constructed with rice husk ash (RHA) as a partial replacement for cement (i.e., 5%, 10%, and 15%) and two different concentrations of soap solutions (i.e., 1 percent and 2 percent). The microstructural studies of RHA, and carbonated samples have been conducted by using Scanning Electron Microscope (SEM) and X-Ray Diffraction (XRD) analysis. According to this study, the carbonation depth of concrete made with 1% and 2% soap solution concentration and without rice husk ash decreased by 11.89% and 46.55%, respectively. From the results, it may also be observed that the carbonation depth of concrete made with up to 10% replacement of cement by rice husk ash led to maximum carbonation resistance, while more than 10% replacement of cement showed higher carbonation depth. It is also observed that the coefficient of permeability of concrete with 2% soap solution significantly decreased as compared to the 1% soap solution and control mix. It may be observed from the SEM images that 0% soap solution (M1) concrete has a very rough concrete surface which may indicate more voids. However, 2% soap solution concrete has a much smoother surface, which indicates a smaller number of voids. Furthermore, the SEM images showed that the soap solution helps in filling the voids of concrete which ultimately helps in reduction in permeability. Energy Dispersive X-Ray Analysis (EDX) of concrete with 0% (M1) and 2% (M6) soap solution disclosed that the concrete with 2% soap solution (M6) exhibited more silica element formation than the concrete with no soap solution (M1).

This paper describes an experimental investigation on the carbonation of Portland pozzolan cement (PPC) concrete with marble dust (MD). The five PPC concrete mixes containing MD (up to 20%) were prepared with three different water–cement ratios (0·5, 0·6 and 0·7). All the concrete cube specimens were exposed to natural atmospheric carbonation after 28 d of moist curing. It was observed that the use of 10% MD enhanced the compressive strength of concrete and the carbonation coefficient decreased with an increase in MD content.

This research reports the experimental outcomes of potentiodynamic analysis of the steel reinforcement in carbonated and uncarbonated high‐volume fly‐ash concrete powder solution extracts (CPSE). Different percentages of fly‐ash content have been used to form a high‐volume fly‐ash concrete (0%, 20%, 40%, 50%, 60%, and 70%) with three different types of steel reinforced. Three different water‐to‐binder ratios (0.35, 0.40, and 0.45) have been used to form the reinforced concrete. The different zones of corrosion were observed through the anodic polarization curve, which was obtained through the potentiodynamic linear sweep test. It has indeed been demonstrated that concrete with up to 50% fly ash shows better resistance against carbonation, as compared to Ordinary Portland Cement (OPC) concrete. Fully active anodic polarization curve is obtained for carbonated concrete. Corrosion‐resistant steel performed better as compared to TATA TMT and SISCON TMT types of steel. The ANOVA also verifies the experimental observation, which shows that the content of fly ash and types of steel decide the extent of corrosion in the concrete. It has also been observed that the interaction between the fly‐ash content and water‐binder proportion and also the interaction between fly ash and the type of steel show the strong effect on the corrosion activity, which decides the extent of different zones of corrosion.

In this paper, the improvement of the performance of a piezoelectric (PZ) cantilever beam using a non-uniform substrate thickness is presented. This reduces the resonant frequency, improves the stress distribution and generates more output voltage and power. Both analytical and finite-element method analyses were performed to investigate the effect of a tapered substrate thickness on a PZ cantilever beam. A tapered substrate thickness was used in rectangular and trapezoidal cantilever structures. All of the designed cantilever structures had the same fabrication area, and their performance was evaluated and compared using an excitation acceleration of 1g (9.8 m/s²). The tapered-down trapezoidal cantilever achieved a minimum resonant frequency of 62.41 Hz, which was 48.83% less than the resonant frequency of the uniform rectangular cantilever beam. The output peak voltage and average power of the proposed tapered-down trapezoidal cantilever beam were 12.36 V and 21 μW, respectively, which were improved by 44 and 74.48%, respectively, compared with those of the uniform rectangular cantilever structure.