Effects of coarse sand dosage on the physic-mechanical behavior of sand concrete

The development and research of a new formulation of concrete integrating natural resources such as sands (from dunes and/or quarries) as well as waste from steel factories in the form of granulated slag from blast furnaces lead to the development of new sand concretes for which the improvement of specific properties will lead to a search for an agreement between production cost and performance. The objective of this research is to study the influence of the dosage of the size of the largest aggregate on the workability of sand concretes as well as on the compressive strength at 7 days, 14 days and 28 days. Five types of concrete are made by substituting aggregates (dune sand and quarry sand) with each other and with different percentages (100%, 75%, 50%, 25% and 0%). The results show that the workability of fresh concrete is considerably influenced by the nature of the sand; the richer the sand in coarse elements, the fineness modulus increases and the more handling improves. In the hardened state, the results show that optimization of the compressive strength is achieved when a good homogeneity of the concrete is achieved and when a large percentage of coarse sand is mixed with a small percentage of fine sand

Constraints on the Parameterized Deceleration Parameter in FRW Universe

Confirmation of accelerated expansion of the universe probed the concept of dark energy theory, and since then, numerous models have been introduced to explain its origin and nature. The present work is based on reconstructing dark energy by parametrization of the deceleration parameter in the FRW universe filled with radiation, dark matter, and dark energy. We have chosen some well-motivated parametrized models 1-3 in an attempt to investigate the energy density in terms of deceleration parameters by estimating the cosmological parameters with the help of different observational datasets. Also, we have introduced a new model 4 for the parametrization of the deceleration parameter. Then we analyzed the cosmography parameters using the best-fit values of the parameters. Using the information criteria, we have examined the viability of the models

Data Analysis of three parameter models of deceleration parameter in FRW Universe

Constraining the dark energy deceleration parameter is one of the fascinating topics in the recent cosmological paradigm. This work aims to reconstruct the dark energy using parametrization of the deceleration parameter in a flat FRW universe filled with radiation, dark energy, and pressure-less dark matter. Thus, we have considered four well-motivated parameterizations of q(z), which can provide the evolution scenario from the deceleration to acceleration phase of the Universe. We have evaluated the expression of the corresponding Hubble parameter of each parametrization by imposing it into the Friedmann equation. We have constrained the model parameter through H(z), Pantheon, and baryons acoustic oscillation (BOA) data. Next, we have estimated the best-fit values of the model parameters by using Monte Carlo Markov Chain (MCMC) technique and implementing H(z)+ BAO+SNe-Ia dataset. Then we analyzed the cosmographic parameter, such as deceleration, jerk, and snap parameters, graphically by employing the best-fit values of the model parameter. Moreover, we have analyzed statefinder and Om diagnostics parameters for each scenario to discriminate various dark energy models. Using the information criteria, the viability of the models have examined. In the end, we have analogized our outcomes with the standard {\Lambda}CDM model to examine the viability of our model

Model-independent study for a quintessence model of dark energy: Analysis and Observational constraints

In this paper, a well-motivated parametrization of the Hubble parameter ($H$% ) is revisited that renders two models of dark energy showing some intriguing features of the late-time accelerating Universe. A general quintessence field is considered as a source of dark energy. We have obtained tighter constraints using recently updated cosmic observational datasets for the considered models. The two models described here show a nice fit to the considered uncorrelated Hubble datasets, Standard candles, Gamma Ray Bursts, Quasars, and uncorrelated Baryonic Acoustic Oscillations datasets. Using the constrained values of the model parameters, we have discussed some features of the late-time accelerating models and obtained the present value of the deceleration parameter ($q_{0}$), the present value of the Hubble parameter ($H_{0}$) and the transition redshift ($z_{t}$) from deceleration to acceleration. The current value of the deceleration parameter for both models is consistent with the Planck 2018 results. The evolution of the geometrical and physical parameters is discussed through graphical representations for both models with some diagnostic analysis. The statistical analysis performed here shows greater results and overall, the outcomes of this investigation are superior to those previously found.Comment: 22 pages, 26 figure

Barrow Entropy and AdS Black Holes in RPS Thermodynamics

In this paper, we examine the restricted phase space (RPS) thermodynamics for charged AdS black holes by considering the impact of quantum gravity on the event horizon area. The primary aim of this work is to elucidate the influence of quantum gravitational effects on thermodynamic behaviors, critical phenomena, phase transitions, and the stability of black holes. We observe that charged AdS black holes exhibit thermodynamic behavior similar to that of Van der Waals fluids when influenced by quantum gravity. Furthermore, we introduce a novel black hole thermodynamic phenomenon, which we term ``resistance of phase transitions". Our study uncovers a violation of the homogeneity property of the Smarr relation in RPS thermodynamics due to the effects of quantum gravity.Comment: 11 pages, 4 figure

Smoothing the H0H_0 tension with a dynamical dark energy model

The discrepancy between Planck data and direct measurements of the current expansion rate $H_0$ and the matter fluctuation amplitude $S_8$ has become one of the most intriguing puzzles in cosmology nowadays. The $H_0$ tension has reached $4.2\sigma$ in the context of standard cosmology i.e $\Lambda$CDM. Therefore, explanations to this issue are mandatory to unveil its secrets. Despite its success, $\Lambda$CDM is unable to give a satisfying explanation to the tension problem. Unless some systematic errors might be hidden in the observable measurements, physics beyond the standard model of cosmology must be advocated. In this perspective, we study a phantom dynamical dark energy model as an alternative to $\Lambda$CDM in order to explain the aforementioned issues. This phantom model is characterised by one extra parameter, $\Omega_{pdde}$, compared to $\Lambda$CDM. We obtain a strong positive correlation between $H_0$ and $\Omega_{pdde}$, for all data combinations. Using Planck measurements together with BAO and Pantheon, we find that the $H_0$ and the $S_8$ tensions are $3\sigma$ and $2.6\sigma$, respectively. By introducing a prior on the absolute magnitude, $M_B$, of the SN Ia, the $H_0$ tension decreases to $2.27\sigma$ with $H_0 = 69.76_{-0.82}^{+0.75}$ km s$^{-1}$ Mpc$^{-1}$ and the $S_8$ tension reaches the value $2.37\sigma$ with $S_8 =0.8269_{-0.012}^{+0.011}$.Comment: 11 pages, 4 figure

Cosmological Tests of f(R,G,T)f(R,G,\mathcal{T}) Dark Energy Model in FRW Universe

This research article presents a new cosmological model formulated within the $f(R,G,\mathcal{T})$ framework, focusing on the observational signatures and parameter constraints of the model. The Markov Chain Monte Carlo (MCMC) technique is employed to effectively explore the parameter space using data from 36 Cosmic Chronometers and 1701 Pantheon Plus data points. A comparative analysis is conducted between the proposed $f(R,G,\mathcal{T})$ model and the widely accepted $\Lambda$CDM model, considering various cosmological parameters, such as Deceleration, Snap, and Jerk. By evaluating these parameters, valuable insights into the dynamics and evolution of the universe within the context of the new model are obtained. Diagnostic tests including Statefinder and Om Diagnostic are performed to further investigate the behavior and consistency of the $f(R,G,\mathcal{T})$ model. These tests provide deeper insights into the properties of the model and its compatibility with observational data. The model is subjected to statistical analysis using Information Criteria to rigorously assess its goodness of fit to the data. This analysis helps determine the level of agreement between the $f(R,G,\mathcal{T})$ model and the observational data, establishing the viability and reliability of the proposed cosmological framework. The results highlight the potential of the $f(R,G,\mathcal{T})$ framework in understanding the fundamental aspects of the universe's evolution and dynamics. The comparative analysis with the $\Lambda$CDM model, along with the comprehensive diagnostic tests performed, demonstrates the efficacy and validity of the $f(R,G,\mathcal{T})$ model in explaining observed cosmological phenomena. These findings contribute to the ongoing pursuit of accurate and comprehensive models that provide a deeper understanding of the nature of our universe.Comment: 19 pages, 10 figures; accepted for publication in EPJ

Observational Constraints and Cosmological Implications of Scalar-Tensor f(R,T)f(R, T) Gravity

Recently, the scalar-tensor representation of $f (R,T)$ gravity was used to explore gravitationally induced particle production/annihilation. Using the framework of irreversible thermodynamics of open systems in the presence of matter creation/annihilation, the physical and cosmological consequences of this setup were investigated in detail. In this paper, we test observationally the scalar-tensor representation of $f(R,T)$ gravity in the context of the aforementioned framework, using the Hubble and Pantheon+ measurements. The best fit parameters are obtained by solving numerically the modified Friedmann equations of two distinct cosmological models in scalar tensor $f(R, T)$ gravity, corresponding to two different choices of the potential, and by performing a Markov Chain Monte Carlo analysis. The best parameters are used to compute the cosmographic parameters, i.e., the deceleration, the jerk and the snap parameters. Using the output resulting from the Markov Chain Monte Carlo analysis, the cosmological evolution of the creation pressure and of the matter creation rates are presented for both models. To figure out the statistical significance of the studied scalar-tensor $f(R,T)$ gravity, the Bayesian and the corrected Akaike information criteria are used. The latter indicates that the first considered model in scalar tensor $f(R,T)$ gravity is statistically better than $\Lambda$CDM, i.e., it is more favored by observations. Besides, a continuous particle creation process is present in Model 1. On the other hand, for large redshifts, in Model 2 the particle creation rate may become negative, thus indicating the presence of particle annihilation processes. However, both models lead to an accelerating expansion of the Universe at late times, with a deceleration parameter equivalent to that of the $\Lambda$CDM model.Comment: 17 pages, 14 figures; accepted for publication in MNRA