Papers by Keyword: Nano-CaCO₃

Abstract: In recent years, polymer-based nanocomposites have been investigated by many researchers due to their enhanced properties. Different types of nanomaterials have been used to produce polymer nanocomposites. One of them is nano-CaCO₃. In the present work, nano-CaCO₃ material reinforced polypropylene (PP) nanocomposites have been fabricated by melt compounding the PP pellets and nano-CaCO₃ masterbatch. The effect of four different loadings of nano-CaCO₃ (0, 5, 10, 15 wt%) on the melt rheological properties of the nanocomposites has been investigated. The morphology of the nanocomposites was analyzed by a Field Emission Scanning Electron Microscopy (FESEM) to study the dispersion state and distribution of nanoCaCO₃ particles in PP matrix. Whereas, the melt rheological behavior of the nanocomposites was analyzed by an oscillatory rheometer. The FESEM micrographs showed that the nano-CaCO₃ particles were well dispersed and distributed in the PP matrix. Additionally, the melt rheological analysis results showed that the complex viscosity of all nanocomposites samples were higher than that of neat PP and increased with increasing nano-CaCO₃ loadings. Furthermore, the complex viscosity data from the rheological test has been fitted by Carreau-Yasuda equation and it was found to be well fitted.

Abstract: Using intermittent bubbling carbonation method to prepare nanoCaCO₃, the effect of crystal orientation agents on the morphology of nanoCaCO₃ was studied. The nanoCaCO₃ was characterized by means of field emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD), Laser particle analyzer. The results showed that the different shapes nanoCaCO₃ was synthesized by adding different crystal orientation agents to control the shape of the product. The as-prepared CaCO₃ were pure calcite crystal and the average particle sizes were within the range of 25.7 to 60.9 nm.

Abstract: Adding different kinds of additives will change rheological properties of cement slurry, same to the concrete. The relationship between fluid shear stress (Γ) and the shear rate (Ds) called rheological properties. In this paper we studied the influence of different additives (Olyacryamide, polycarboxylate superplasticizer , nanoCaCO₃) on the slurry rheological properties and the effects of polyacrylamide on cement mortar liquidity.

Abstract: Adjusting the proportion of gases and stirring rate and other parameters, the value of pH, electrical conductivity, electrode potential, temperature of the system were tested online under different parameters. According to the results of scanning electron microscopy , the coating effect of different reaction stages and the influence of different coating processes were analyzed.

Abstract: To provide polypropylene (PP) with better excellent mechanical properties, nanoCaCO₃ particles are incorporated into PP matrix by melt blending in this work. To improve the mophology between PP and nanoCaCO₃, maleic-anhydride grafted PP (PP-g-MAH) was added as a compatibiliser. The results showed that PP-g-MAH indeed enhanced the interfacial adhesion of PP /nanoCaCO₃ composites, which is demonstrated by the measurement of scanning electron microscope (SEM). The results of tensile tests revealed that the inclusion of nanoCaCO₃ slightly increased modulus and decreased tensile strength and significantly increased the elongation at break. At high fraction of nanoCaCO₃, the elongation at break was declined. The nanosized feature, shape and dispersion conditions of nanoCaCO₃, played important roles in determining the performances of PP/nanoCaCO₃ composites.

Abstract: This paper presents an experimental study to evaluate the effects of fly ash and nanoCaCO₃ on setting time of cement paste. The test group included the contents of fly ash was 30%, 40%, 50%, 60% and content of nanoCaCO₃ was 2.5%, 5%, 10%, 20%. Results indicate that setting time was increased with the incorporation of fly ash, shortened with the incorporation of nanoCaCO₃. The incorporation of 5% nanoCaCO₃ by mass of cementitious materials reduced initial and final setting times by 60 and 70 min, respectively. In comparison to the referenced paste with 40% fly ash. The best fly ash content appear to be 40% when nanoCaCO₃ was added.

Abstract: In this paper, the current situation of nanomaterials used in concrete were introduced, mechanism of nanomaterilas was reviewed. Recent application of nanomaterilas in special concrete such as air purified concrete, eco-concrete, high tenacity concrete were present.

Abstract: In this work, CaCO₃ nanoparticles have been synthesized via heat-treatment of a new precursor. Effect of calcinations temperature on particle size has been investigated. The products were characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). nanoCaCO₃ was modified using chloroform as solvent and fatty acid as modifier atroom temperature. The advantage of this modification is that it can be proceed at room temperature and it can reduce energy consumption.

Abstract: The effect of fly ash and nanoCaCO₃ on the viscosity of pastes was studied. The rheological value of cement paste was determined by the rotation rheometer NXS-11B. In the study, five different dosages (0%, 20%, 30%, 40%, and 50%) of fly ash and three levels of nanoCaCO₃, 0.5%, 1%, and 2.5%, were considered. Viscosity of the pastes, made with fly ash and nanoCaCO₃ at a constant water-to-binder ratio of 0.35, were measured and analyzed. The results indicate that the pastes with fly ash or/and nanoCaCO₃ still fit the Bingham model. The addition of fly ash reduced viscosity, however, the addition of nanoCaCO₃ increased viscosity. The effect of nanoCaCO₃ is more significantly than fly ash on viscosity.

Abstract: The work described in this document forces on composite strengthening technique of recycled aggregate. In this experiment, recycled aggregates are soaked in different types and different concentrations of nanomaterials to strengthen. This research estimates the strengthening effects by comparing the properties of recycled aggregate soaked in different materials, and proves that the composite proportioning has better effect.