Explore the vast range of titles available.

Cold rolling has detrimental effect on the formability of sheet metals. It is, however, inevitable in producing sheet high quality surfaces. The effects of cold rolling on the forming limits of stretch sheets are not investigated comprehensively in the literature. In this study, a through experimental study is conducted to observe the effect of different cold rolling thickness reduction on the formability of sheet metals. Since the experimental procedure of such tests are costly, an artificial intelligence is also adopted to predict effects of cold thickness reduction on the formability of the sheet metals. In this regard, St14 sheets are examined using tensile, metallography, cold rolling and Nakazima’s hemi-sphere punch experiments. The obtained data are further utilized to train and test an adaptive neural network fuzzy inference system (ANFIS) model. The results indicate that cold rolling reduces the formability of the sheet metals under stretch loading condition. Moreover, the tensile behavior of the sheet alters considerably due to cold thickness reduction of the same sheet metal. The trained ANFIS model also successfully trained and tested in prediction of forming limits diagrams. This model could be used to determine forming limit strains in other thickness reduction conditions. It is discussed that determination of forming limit diagrams is not an intrinsic property of a chemical composition of the sheet metals and many other factors must be taken into account.

Despite cement’s superior performance and inexpensive cost compared to other industrial materials, crack development remains a persistent problem in concrete. Given the comparatively low tensile strength, when cracks emerge, a pathway is created for gas and water to enter the cementitious matrix, resulting in steel reinforcement corrosion which compromises the durability of concrete. Superabsorbent hydrogels have been developed as a novel material for enhancing the characteristics of cementitious materials in which they have been demonstrated to decrease autogenous shrinkage and encourage self-healing. This study will detail the design and application of polyelectrolyte hydrogel particles as internal curing agents in concrete and provide new findings on relevant hydrogel–ion interactions. When hydrogel particles are mixed into concrete, they generate their stored water to fuel the curing reaction that results in less cracking and shrinkage, thereby prolonging the service life of the concrete. The interaction of hydrogels with cementitious materials is addressed in this study; the effect of hydrogels on the characteristics and self-healing of cementitious materials was also studied. Incorporating hydrogel particles into cement decreased mixture shrinkage while increasing the production of particular inorganic phases within the vacuum region formerly supplied by the swollen particle. In addition, considering the control paste, cement pastes containing hydrogels exhibited less autogenous shrinkage. The influence of hydrogels on autogenous shrinkage was found to be chemically dependent; the hydrogel with a delayed desorption rate displayed significantly low shrinkage in cement paste.

Marble has been commonly used as a building material since ancient times. The disposal of waste materials from the marble industry, consisting of sludge that is composed of powder mixed with water, is one of the current worldwide environmental problems. This experimental study aims to valorize marble powder, which is achieved by grinding the sludge as filler added to the cementitious matrix of self-compacting concrete (SCC). The main purpose of this work is to evaluate the marble filler effects on the rheology in the fresh state and on the hardened properties of SCCs compared to those of limestone filler. To this end, two SCCs, SCCM and SCCL, manufactured using marble powder and limestone filler, respectively, were prepared and tested. The fresh properties of the two SCCs’ mixtures were determined by slump flow, L-box, V-funnel, sieve stability, bulk density, and air content. Tests on hardened SCCs included compressive strength, homogeneity, and quality in terms of ultrasonic pulse velocity and durability against carbonation and water penetration. In addition, scanning electron microscope (SEM) and X-ray diffraction (XRD) were used to analyze the specimens.

The present work focused on the experimental study of the mechanical, thermal and acoustic properties of cement composite reinforced using Posidonia oceanica (PO) fibers. For this purpose, parallelepipedic specimens of dimensions 270 mm × 270 mm × 40 mm and cubic specimens of dimensions 150 mm × 150 mm × 150 mm were prepared with a water-to-cement ratio of 0.50 by varying the volume of fibers (Vf) from 0% to 20%. Properties such as compressive strength, thermal conductivity, thermal diffusivity, standardized level difference and sound transmission class were examined. The compressive strength of the specimens was determined using the rebound hammer test, while the thermal measurements were performed with the steady-state box method. The results showed that the addition of PO fibers improved the compressive strength of the mixtures and produced a maximum value of 33.60 MPa for a 10% volume of fiber content. Thermal conductivity and thermal diffusivity decreased significantly with the addition of fibers for all the mixtures. The experimental investigation also showed that the sound transmission class of PO-fiber-reinforced cementitious composites decreased as the fiber volume increased due to an increase in air voids in the mixtures.

The purpose of the present study is to recover marble waste and expanded perlite aggregate (EPA) for use as an additive to cementitious matrix building materials. The main goal is to produce a new insulation block floor from lightweight concrete (LC) by mixing sand from the waste marble crushing process (SWM), natural sand, and EPA. First, optimal mixture of natural sand, SWM, and EPA was determined for a given insulation LC. To this end, plate and cubic specimens were prepared by varying the volume proportion of SWM to natural sand in percentages of 0, 20, 40, 60, 80, and 100. Mechanical and physical properties such as the compressive strength, thermal conductivity, thermal diffusivity, specific heat capacity, and sound reduction index at different frequencies were investigated. Finally, a prototype of a new insulation lightweight block floor was manufactured from the optimal mixture of the studied LC. The results showed that the incorporation of SWM significantly improved the mechanical properties and the thermal insulation of LC compared to those of the natural sand. These results are promising and give the present insulation block floor the opportunity to be used in composite slabs.

The marble powder (MP), obtained from waste sludge marble processing, has a high specific surface area; this could mean that it can be used as filler added to self-compacting concrete (SCC). The aim of this experimental work is to study the effects of the cement-MP paste volume on the rheology in the fresh state and the hardened properties (compressive strength) of SCC by a microstructure analysis on paste samples with different amounts of MP. For all pastes, the morphological forms and the chemical composition of the main mineral components were analyzed by the scanning electron microscope (SEM) and X-ray diffraction (XRD). The hydration, microstructure, and mineralogical changes has been studied. Experimental results show that the cement-MP paste volume has significant effects on the self-compacting and the self-leveling properties in the fresh state of SCC. In addition, the paste volume has a significant contribution on the compressive strength of SCC. Results indicate also that the difference in chemical composition between MP and cement have not any contribution on the paste volume effects.

The compressive strength, shrinkage, elasticity, and electrical resistivity of the cement-soil pastes (slag, fly ash) of self-healing of cementitious concrete have been studied while adding hydrogels with nano silica (NSi) in this research. Defining the hydraulic and mechanical properties of these materials requires improvement to motivate more uptake for new buildings. Initially, examining the impact of different synthesized hydrogels on cement-soil pastes showed that solid particles in the mixtures highly affected the absorption capacity of NSi, representing the importance of direct interactions between solid particles and hydrogels in a cementitious matrix. All test results were analyzed by use of a hybridized soft computing model such as the adaptive neuro fuzzy inference system (ANFIS) and support vector regression (SVR) for precise studying and the avoidance of few empirical tests or error percentages. Subsequently, the best RMSE of ANFIS is 0.6568 and the best RMSE of SVM is 1.2564; the RMSE of ANFIS-SVM (0.5643) in the test phase is also close to zero, showing a better performance in hypothesizing self-healing soil-cementitious hydrogel materials in mine backfill. The R2 value for ANFIS-SVM is 0.9547, proving that it is a proper model for predicting the study’s goal. Electrical resistivity and compressive strength declined in the cement-soil pastes including hydrogels according to experimental outcomes; it was lowered by the increase of NSi concentration in the hydrogel. There was a decrement in the autogenous shrinkage of cement-soil pastes while adding hydrogel, depending on the NSi concentration in the hydrogels. The findings of this research are pivotal for the internal curing of cementitious materials to define the absorption of hydrogels.

Currently, marble waste is valued by incorporating powders, obtained by drying and grinding sludge resulting from marble blocks cutting operation, or the aggregates, obtained by crushing the solid waste, on self-compacting concrete. These two procedures require a lot of energy. This experimental and theoretical work focuses on the direct incorporation of marble sludge in self-compacting concrete. The first part needs the study of the rheological behavior of the marble sludge grout (MSG) as a function of the added water amount. For this, different grouts were prepared and tested by varying the water/sludge ratio. In the second part, four self-compacting concretes (SCCs) were mixed with MSG having different water/sludge ratios in order to validate a new technique of gassing self-compacting concrete with MSG. The test results show that the marble grains of grout is totally dispersed when the water/sludge ratio was equal to 1.2. The results also show that the gassing with MSG allows us to obtain SCC having both self-compacting property and self-leveling property compared to SCC made by adding marble filler to the cementitious matrix.

While adding superabsorbent polymer hydrogel particles to fresh concrete admixtures, they act as internal curing agents that absorb and then release large amounts of water and reduce self-desiccation and volumetric shrinkage of cement that finally result in hardened concrete with increased durability and strength. The entrainment of microscopic air bubbles in the concrete paste can substantially improve the resistance of concrete. When the volume and distribution of entrained air are adequately managed, the microstructure is protected from the pressure produced by freezing water. This study addresses the design and application of hydrogel nanoparticles as internal curing agents in concrete, as well as new findings on crucial hydrogel–ion interactions. When mixed into concrete, hydrogel particles produce their stored water to power the curing reaction, resulting in less volumetric shrinkage and cracking and thereby prolonging the service life of concrete. The mechanical and swelling performance qualities of the hydrogel are very sensitive to multivalent cations found naturally in concrete mixes, such as aluminum and calcium. The interactions between hydrogel nanoparticles and alkaline cementitious mixes are described in this study, while emphasizing how the chemical structure and shape of the hydrogel particles regulate swelling behavior and internal curing efficiency to eliminate voids in the admixture. Moreover, in this study, an artificial neural network (ANN) was utilized to precisely and quickly analyze the test results of the compressive strength and durability of concrete. The addition of multivalent cations reduced swelling capacity and changed swelling kinetics, resulting in fast deswelling behavior and the creation of a mechanically stiff shell in certain hydrogel compositions. Notably, when hydrogel particles were added to a mixture, they reduced shrinkage while encouraged the creation of particular inorganic phases within the void area formerly held by the swelled particle.

Bamboo is deemed an emerging constructional material with promising application projections due to the reliable natural properties and advantageous structural characteristics. However, there is a lack of systematic studies on the mechanical characteristics of the bamboo species from a microstructural scale. Hence, this paper investigated the primary mechanical properties of the bamboo specimens (Dendrocalamus asper) with further microstructural analysis on the bamboo failure. The direct tensile strength of bamboo specimens was about 226.45 MPa, while the final splitting tensile modulus was found to be 2.88 MPa. Microstructural characterisation of the failed tensile specimens indicates that fibre debonding is the main failure mechanism under tensile conditions. On the other hand, splitting and end bearing failure were found on compression test specimens. In addition, nanoindentation tests were carried out on different cell structures to articulate the hardness and Young’s modulus. The elastic modulus of the fibre cell walls is three times that of the parenchyma cell walls, yet the hardness values are comparable. This confirms that the specimen failure of previous macromechanical testing is due to crack propagation along the parenchyma cells, instead of the cell walls. Based on the experimental studies discussed in this paper, the conclusion can convey a positive message regarding the ability of bamboo as a primary sustainable substitute for conventional construction materials.