Journal of Materials and Engineering Structures
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Mechanical and durability performance of concrete incorporating graphene oxide
Get PDFThis current investigation was conducted to explore the influence of graphene oxide (GO) on the mechanical and durability properties of normal concrete. A total of five mixes were prepared in addition of laboratory synthesized GO ranging from 0-0.8% with an increment of 0.02% by weight of cement. The synthesized GO was characterized using SEM, FT-IR and XRD techniques. The workability, initial surface absorption and sorptivity values were observed to have reduced with increase in GO content in the cement matrix. Whereas, the ultrasonic pulse velocity (UPV), compressive and tensile strength were observed to enhance with percentage increment of GO in the concrete compare to control mix. The microstructural analysis was performed using SEM/EDX at 90 days curing age. The mix with 0.08% GO showed better result compared to rest of the mixes with GO and control mix
Effects of Poly Vinyl Acetate on Characteristics of Expansive Soil
Get PDFSoil stabilization using polymer materials has become of great potential in recent years. In this regard, an attempt is made to investigate and understand the influence of Poly Vinyl Acetate (PVA) on the engineering properties of expansive soil. A series of treated soil specimens were prepared and tested at four different percentages of PVA (0%, 1.5%, 3.75%, and 5% by weight of dry soil). These treated specimens were subjected to laboratory testing for measuring Atterberg's limits, free swell, compaction characteristics, and unconfined compression strength properties. It was found that PVA had significant influence on the properties of treated soil. An increase in PVA content resulted in an increment of unconfined compressive strength of the soil. Addition of 3.75% of PVA increased the unconfined compressive strength value almost 6 times the value of the virgin soil. On the other hand, an increase in PVA content led to a reduction of free swell and plasticity index. The soil plasticity and free swell indices values were reduced from 62% to 0% and from 190% to 50% respectively by addition of 5% PVA. It can be concluded that an increasing trend for soil strength and decreasing in swelling with addition of PVA, suggesting its potential applications in stabilization of expansive soils
Sorption mechanism of copper ions on synthetic and natural dentine hydroxyapatites
Get PDFRemoval of copper ions from aqueous solutions on synthetic and dentine waste hydroxyapatites (HAP) was investigated in batch sorption experiments. Kinetics of sorption followed a pseudo-first order model. Steady-state data show agreement with the Sips isotherm compared with Freundlich and Langmuir models. The higher surface area and carbonated nature of synthetic hydroxyapatite were not sufficient to reach higher sorption capacity than natural one. Ion-exchange and precipitation contributed on removal of Copper despite level ionization of hydroxyapatites. Proton and metal exchanges with copper ions contributed to process of sorption with prevalence of proton-exchange at low copper ion concentrations. High temperatures promoted the removal efficiency of Cu(II) onto the natural and synthesised hydroxyapatites. The thermodynamic parameters showed that sorption process was spontaneous, endothermic and associated entropy at the solid/solution interface increased at high temperatures
Estimation of compressive strength of high-strength concrete by random forest and M5P model tree approaches
Get PDFHigh strength concrete (HSC) define as the concrete that meets a unique mixture of performance uniformity requirements that cannot be reached routinely using conventional constituents and regular mixing, placing, and curing events. The modeling of such type of concrete is very difficult. In this investigation, the performance of the random forest regression and M5P model tree were compared to estimate the 28th day compressive strength of the HSC. Total data set consists of 83 data out of which 70 % of the total dataset used to train the model and residual 30 % used to test the models. The accuracy of the models was depending upon the three performance evaluation parameters which are correlation coefficient (R), root mean square error (RMSE) and maximum absolute error (MAE). The results recommend that random forest regression is more accurate to predict the compressive strength as compare to M5P model tree. Sensitivity analysis indicates that water (W) and Silica fumes (SF) are the most valuable constituents of the HSC and compressive strength mainly depends on these constituents
Development and Characterization of E-Glass Particulate Reinforced Epoxy Composite for Automobile Application
Get PDFThe structure and mechanical properties of epoxy composites reinforced with E-glass particles have been evaluated to assess the possibility of using the composite as a new material for car bumper fabrication. Epoxy resin of the type LY556 reinforced with 5 – 25% of E-glass particles added at 5% intervals was investigated. The fabrication of E-glass particle reinforced epoxy composite was successful and a prototype car bumper was made. The newly developed E-Glass particles/epoxy composites were characterized for their mechanical and structural properties using Thermo-Gravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), X-Ray Diffraction Analysis (XRD), Tensile, Flexural, and Impact tests. The results showed that 20 wt. % glass particle addition gave the ultimate mechanical properties with tensile and flexural strengths of 154.5 and 181.55 MPa respectively. SEM morphology had also shown good adhesion between fibers and polymer matrix up to 20 wt. % glass particle addition with minimal segregation of reinforcement glass particles. Thermal stability of the composite was not impaired going by a stable degradation temperature (Td) after E-glass particles addition. A prototype bumper was fabricated from epoxy-15 wt% E glass particle composite possessing peak impact energy
Experimental study of the long-term shortening of reinforced concrete columns under maintaining concentric axial load
Get PDFThis paper presents the results of an experimental study to measure the shortening of reinforced concrete (RC) columns under long-term maintaining concentric axial load. Long-term axial deformation due to shrinkage and creep of the concrete were recorded beside deformation due to mechanical load. Eight RC cylinder - columns (content of reinforcement 1.5% and 2%) with diameter of 150 mm and height of 600 mm were tested during the period of 600 days to determine their shortening. The experimental results showed that the long-term deformation of RC columns occurs primarily during the first year of loading. The deformation creep of concrete is much greater than the shrinkage deformation. The reinforcement content has a significant effect on the long-term deformation of concrete columns
Durability of Portland Cements Composed of Industrial Waste Fillers in an Acidic Environment
Get PDFCe travail expérimental étudie la durabilité de mortiers réalisés avec un ciment Portland composé de fillers industriels : laitier granulé et poudre de marbre. Les échantillons sont conservés durant 12 mois dans l’acide sulfurique. L’évolution des phases cristallines est suivie par diffraction X et les minéraux sont observés au MEB, la microanalyse qui lui est associée permet de confirmer leur composition chimique. Les résultats montrent qu’à une concentration de 0,05M, les hydrates du ciment (CSH, CH, ettringite) ne semblent pas affectés à l’intérieur de l’échantillon, le soufre est y totalement absent. En revanche, les mortiers exposés à une forte concentration (0,25M) en acide sulfurique développent un dépôt extérieur dense de gypse. Le mécanisme de l'attaque est principalement dû à l'action expansible du gypse.Ce travail expérimental étudie la durabilité de mortiers réalisés avec un ciment Portland composé de fillers industriels : laitier granulé et poudre de marbre. Les échantillons sont conservés durant 12 mois dans l’acide sulfurique. L’évolution des phases cristallines est suivie par diffraction X et les minéraux sont observés au MEB. La microanalyse (EDS) qui lui est associée permet de confirmer leur composition chimique. Les résultats montrent qu’à une concentration de 0,05M, les hydrates du ciment (CSH, CH, ettringite) ne semblent pas affectés à l’intérieur de l’échantillon, le soufre est y totalement absent. En revanche, les mortiers exposés à une forte concentration (0,25M) en acide sulfurique développent un dépôt extérieur dense de gypse. Le mécanisme de l'attaque est principalement dû à l'action expansible du gypse.This experimental work studies the durability of mortars made with Portland cement composed of industrial fillers: granulated slag and marble powder. Samples of normal mortar were exposed for 12 months to sulphuric acid. The evolution of crystalline phases was analyzed by XRD and minerals were observed by SEM. Microanalysis (EDS linked to SEM) confirms their chemical composition. For a low concentration of sulphate (0.05 mol/l), the results show that the hydrates of cement (CSH, CH, ettringite) seem unaffected in the interior of the sample where the sulphur is completely absent. However in the case of attack by a high concentration (0.25 mol/l) of sulphuric acid, samples develop a dense surface gypsum deposit. The mechanism of the attack is mainly due to the expansive action of gypsum
Adhesion and rheology of joints fresh mortars
Get PDFAn adhesive mortar in fresh state is considered as a granular suspension in a complex fluid. The study of the rheological behavior of such materials involves the rheology of complex fluids, including granular suspensions, colloidal dispersions, etc... To characterize the rheological behavior of an adhesive mortar, in quasi-static regime, we use a three-parameter behavior law that includes a yield stress, a viscosity coefficient and a fluidity index. The adhesiveness of the mortar can be characterized by identifying the evolution of the adhesive force, the cohesive force and the adherence force. The mortar characteristics are measured by a commercial rheometer from Texas Instruments (TA). In this study, we use a plane-plane geometry for the Probe Tack Test to determine the adhesiveness of the materials. The rheological property of the mortar is investigated using the Vane-Cylinder geometry (figure 1.5). The mechanisms of separation and rupture in a tensile material confined between two parallel plates are studied theoretically and experimentally. This study is conducted for a materials selected for his rheological behavior (Herschel Buckley). We studied the rheological behavior and the influence of additions of organic additives on the rheological parameters intrinsic to the material, and the failure mechanisms. This study has allowed us to observe the different types of rupture
Use of crushed clay brick waste as dune sand granular corrector in mortar manufacturing
Get PDFThe present study aims to investigate the possibility of using crushed clay brick waste as dune sand granular corrector in mortar manufacturing. The mixtures composition method is based on the progressive substitution of dune sand with crushed waste at different weight contents; 5, 10, 15, 20 and 25%. The effect of these recycled materials was studied in an experimental programme through several tests. The performance of these modified mortars was evaluated in terms of strength, workability, water absorption, and resistance to sulfuric acid attack. The results obtained show that the incorporation of the used waste has a significant influence on the behavior of the mortar, in the fresh state and the hardened state. Further to this, it has also been observed that its inclusion with certain percentages makes it possible to obtain performances comparable to those of the alluvial sand-based mortar, which demonstrates its effectiveness in improving the various properties of the mortar
Structure of the out- flows behind buildings and Influence of the geometry of the streets on the out-flows
Get PDFThis paper intends to study the latest results from the research methods available with special intentions given to the architectural effects of the street valley and wind speed. Extensive research has been carried out through several research approaches to understand the effect of wind flow formation in the streets and the current wind condition on the structure of the wind current. The main goal of this paper is to study the structure of out- flows of buildings and the effect of street engineering on external flows. The numerical modeling is to simulate the effect of the wind flow and the layer limit on different building structures using the ANSYS Fluent package. The program was based on the K-ε model to incorporate the potential of differential equations forming the mathematical model. Three cases were considered; the first case is the height-to-width ratio of the valley (h/w), the second is the width of the dome (b3/b) and the third case the ratio of the height of the valley (h3/h) to see the effect of street valley engineering and wind speed effect