scholarly journals Analysis of Chemical Composition of Portland Cement in Ghana: A Key to Understand the Behavior of Cement

2015 ◽  
Vol 2015 ◽  
pp. 1-5 ◽  
Author(s):  
Mark Bediako ◽  
Eric Opoku Amankwah
Keyword(s):  
Chemical Composition ◽  
Portland Cement ◽  
Ordinary Portland Cement ◽  
Chemical Compositions ◽  
Test Results ◽  
Brand Name ◽  
X Ray ◽  
Portland Limestone Cement ◽  
Limestone Cement ◽  
Construction Works

The performance of Portland cement in concrete or mortar formation is very well influenced by chemical compositions among other factors. Many engineers usually have little information on the chemical compositions of cement in making decisions for the choice of commercially available Portland cement in Ghana. This work analyzed five different brands of Portland cement in Ghana, namely, Ghacem ordinary Portland cement (OPC) and Portland limestone cement (PLC), CSIR-BRRI Pozzomix, Dangote OPC, and Diamond PLC. The chemical compositions were analyzed with X-Ray Fluorescence (XRF) spectrometer. Student’st-test was used to test the significance of the variation in chemical composition between standard literature values and each of the commercial cement brands. Analysis of variance (ANOVA) was also used to establish the extent of variations between chemical compositions and brand name of the all commercial Portland cement brands. Student’st-test results showed that there were no significant differences between standard chemical composition values and that of commercial Portland cement. The ANOVA results also indicated that each brand of commercial Portland cement varies in terms of chemical composition; however, the specific brands of cement had no significant differences. The study recommended that using any brand of cement in Ghana was good for any construction works be it concrete or mortar formation.

Compressive Strength and Shrinkage Behavior of Concrete Produced from Portland Limestone Cement with Water Absorption Polymer Balls

2020 ◽  
Vol 857 ◽  
pp. 83-88
Author(s):  
Ikram F. Ahmed Al-Mulla ◽  
Ammar S. Al-Rihimy ◽  
Mushriq F. Al-Shamaa
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Water Absorption ◽  
Ordinary Portland Cement ◽  
Drying Shrinkage ◽  
Internal Curing ◽  
Early Age ◽  
Portland Limestone Cement ◽  
Limestone Cement ◽  
Shrinkage Behavior

From the sustainability point of view a combination of using water absorption polymer balls in concrete mix produce from Portland limestone cement (IL) is worth to be perceived. Compressive strength and drying shrinkage behavior for the mixes of concrete prepared by Ordinary Portland Cement (O.P.C) and Portland limestone cement (IL) were investigated in this research. Water absorbent polymer balls (WAPB) are innovative module in producing building materials due to the internal curing which eliminates autogenous shrinkage, enhances the strength at early age, improve the durability, give higher compressive strength at early age, and reduce the effect of insufficient external curing. Polymer balls (WAPB) had been used in the mixes of this research to provide good progress in compressive strength with time. Water absorption polymer balls have the ability to absorb water and after usage in concrete it will spill it out and shrink leaving voids of their own diameter before shrinking that lead to provide internal curing. The required quantity of water for the mixes were reduced due to the addition of water from the absorption polymers. Mixes produced from Portland limestone cement in this research show drying shrinkage results and compressive strength results lower than mixes made from ordinary Portland cement.

scholarly journals Inventive Microstructural and Durability Investigation of Cementitious Composites Involving Crystalline Waterproofing Admixtures and Portland Limestone Cement

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1425 ◽  
Author(s):  
Pejman Azarsa ◽  
Rishi Gupta ◽  
Alireza Biparva
Keyword(s):  
Chemical Elements ◽  
Cementitious Composites ◽  
Chemical Compositions ◽  
Crystal Formation ◽  
Polished Section ◽  
Limited Information ◽  
Sem Images ◽  
X Ray ◽  
Portland Limestone Cement ◽  
Limestone Cement

The durability of a cement-based material is mainly dependent on its permeability. Modifications of porosity, pore-structure and pore-connectivity could have significant impacts on permeability improvement, which eventually leads to more durable materials. One of the most efficient solutions in this regard is to use permeability reducing admixtures (PRA). Among these admixtures for those structures exposed to hydro-static pressure, crystalline waterproofing admixtures (CWA) have been serving in the construction industries for decades and according to ACI 212—chemical admixtures’ report, it has proven its capability in permeability reduction and durability-enhancement. However, there is substantial research being done on its durability properties at the macro level but very limited information available regarding its microstructural features and chemical characteristics at the micro level. Hence, this paper presents one of the first reported attempts to characterize microstructural and chemical elements of hydration products for cementitious composites with CWA called K, P and X using Scanning Electron Microscopy (SEM). Backscattered SEM images taken from a polished-section of one CWA type—K—admixture were analyzed in ImageJ to obtain paste matrix porosity, indicating a lower value for the CWA-K mixture. X-ray analysis and SEM micrographs of polished sections were examined to identify chemical compositions based on atomic ratio plots and brightness differences in backscatter-SEM images. To detect chemical elements and the nature of formed crystals, the fractured surfaces of three different CWA mixtures were examined. Cementitious composites with K admixture indicated needle-like crystal formation—though different from ettringite; X and P admixtures showed sulfur peaks in Energy Dispersive Spectrum (EDS) spectra, like ettringite. SEM images and X-ray analyses of mixtures incorporating Portland Limestone Cement (PLC) indicated lower-than-average porosity but showed different Si/Ca and Al/Ca atomic ratios.

scholarly journals Characterization of the microstructure, microsegregation, and phase composition of ex-situ Fe–Ni–Cr–Al–Mo–TiCp composites fabricated by three-dimensional plasma metal deposition on 10CrMo9–10 steel

2020 ◽  
Vol 20 (4) ◽  
Author(s):  
Łukasz Rakoczy ◽  
Kevin Hoefer ◽  
Małgorzata Grudzień-Rakoczy ◽  
Bogdan Rutkowski ◽  
Marcin Goły ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Composite Coatings ◽  
Thermodynamic Simulation ◽  
Iron Concentration ◽  
Ex Situ ◽  
Chemical Compositions ◽  
Powder Mixtures ◽  
Equivalent Radius ◽  
X Ray ◽  
The Matrix

Abstract Quaternary powder mixtures yNi–20Cr–1.5Al–xTiCp (y = 78.5, 73.5, 68.5; x = 0, 5, 10) were deposited on ferritic 10CrMo9–10 steel to form on plates ex-situ composite coatings with austenitic-based matrix. Plasma deposition was carried out with various parameters to obtain eight variants. The microstructure, chemical composition, phase constitution, phase transformation temperatures, and microhardness of the two reference TiCp-free coatings and six ex-situ composites were investigated by X-ray diffraction, scanning and transmission electron microscopy, energy-dispersive X-ray spectroscopy, thermodynamic simulation, and Vickers microhardness measurements. All composites had an austenite matrix with lattice parameter a = 3.5891–3.6062 Å, calculated according to the Nelson–Riley extrapolation. Microstructural observations revealed irregular distribution of TiCp in the composites. Large particles generally occurred near the external surface due to the acting buoyancy effect, whereas in the interior smaller particles, with an equivalent radius around 0.2–0.6 μm, were present. Due to initial differences in the chemical composition of powder mixtures and also subsequent intensive mixing with the low-alloy steel in the liquid pool, the matrix of the composites was characterized by various chemical compositions with a dominating iron concentration. Interaction of TiCp with matrix during deposition led to the formation of nano-precipitates of M23C6 carbides at the interfaces. Based on the ThermoCalc simulation, the highest solidus and liquidus temperatures of the matrix were calculated to be for the composite fabricated by deposition of 73.5Ni–20Cr–1.5Al–5TiCp powder mixture at I = 130 A. The mean microhardness of the TiCp-free coatings was in the range 138–146 μHV0.1, whereas composites had hardnesses at least 50% higher, depending on the initial content of TiCp.

scholarly journals Hot bubbles of planetary nebulae with hydrogen-deficient winds

2018 ◽  
Vol 620 ◽  
pp. A98 ◽  
Author(s):  
R. Heller ◽  
R. Jacob ◽  
D. Schönberner ◽  
M. Steffen
Keyword(s):  
Chemical Composition ◽  
High Resolution ◽  
Thermal Conduction ◽  
Thermal Structure ◽  
Neutral Hydrogen ◽  
Planetary Nebulae ◽  
Chemical Compositions ◽  
Heat Conducting ◽  
X Ray ◽  
Similar Solutions

Context. The first high-resolution X-ray spectroscopy of a planetary nebula, BD +30° 3639, opened the possibility to study plasma conditions and chemical compositions of X-ray emitting “hot” bubbles of planetary nebulae in much greater detail than before. Aims. We investigate (i) how diagnostic line ratios are influenced by the bubble’s thermal structure and chemical profile, (ii) whether the chemical composition inside the bubble of BD +30° 3639 is consistent with the hydrogen-poor composition of the stellar photosphere and wind, and (iii) whether hydrogen-rich nebular matter has already been added to the bubble of BD +30° 3639 by evaporation. Methods. We applied an analytical, one-dimensional (1D) model for wind-blown bubbles with temperature and density profiles based on self-similar solutions including thermal conduction. We also constructed heat-conduction bubbles with a chemical stratification. The X-ray emission was computed using the well-documented CHIANTI code. These bubble models are used to re-analyse the high-resolution X-ray spectrum from the hot bubble of BD +30° 3639. Results. We found that our 1D heat-conducting bubble models reproduce the observed line ratios much better than plasmas with single electron temperatures. In particular, all the temperature- and abundance-sensitive line ratios are consistent with BD +30° 3639 X-ray observations for (i) an intervening column density of neutral hydrogen, NH = 0.20-0.10+0.05 × 1022cm−2, (ii) a characteristic bubble X-ray temperature of TX = 1.8 ± 0.1 MK together with (iii) a very high neon mass fraction of about 0.05, virtually as high as that of oxygen. For lower values of NH, we cannot exclude the possibility that the hot bubble of BD +30° 3639 contains a small amount of “evaporated” (or mixed) hydrogen-rich nebular matter. Given the possible range of NH, the fraction of evaporated hydrogen-rich matter cannot exceed 3% of the bubble mass. Conclusions. The diffuse X-ray emission from BD +30° 3639 can be well explained by models of wind-blown bubbles with thermal conduction and a chemical composition equal to that of the hydrogen-poor and carbon-, oxygen-, and neon-rich stellar surface.

scholarly journals Development of Eco-Concrete Produced with Calcined Marl Clay as Cement Replacement Material

2021 ◽  
Vol 21 (4) ◽  
pp. 129-137
Author(s):  
Young-Min Kim ◽  
Ji-Su Kim ◽  
Tong-Seok Han
Keyword(s):  
Portland Cement ◽  
Co2 Emissions ◽  
Co2 Emission ◽  
Ordinary Portland Cement ◽  
Chemical Resistance ◽  
Raw Materials ◽  
Performance Difference ◽  
Test Results ◽  
Replacement Ratio ◽  
Cement Replacement

Because of the increase in greenhouse gas emissions and the enforcement of environmental regulations, efforts to reduce CO2 emissions continue. In this study, calcined marl clay was used as a cement replacement material to minimize CO2 emissions by reducing the cement amount used. The raw materials for marl clay were analyzed, and the durability and chemical resistance of concrete produced with marl clay were examined. From the test results, the optimum replacement ratio of calcined marl clay was determined, and the performance difference with ordinary Portland cement (OPC) concrete was identified. The performance of the eco-concrete was comparable to that of the OPC concrete containing marl clay when the cement was optimally replaced with marl clay. Furthermore, the CO2 emission for each specimen was calculated. This study demonstrated the feasibility of developing eco-friendly concrete using calcined marl clay.

scholarly journals CALCIUM OXIDE CHARACTERISTICS PREPARED FROM AMBUNTEN’S CALCINED LIMESTONE

2018 ◽  
Vol 5 (1) ◽  
pp. 65 ◽  
Author(s):  
Fatimatul Munawaroh ◽  
Laila Khamsatul Muharrami ◽  
Triwikantoro Triwikantoro ◽  
Zaenal Arifin
Keyword(s):  
Calcium Carbonate ◽  
Chemical Composition ◽  
Calcium Oxide ◽  
Crystalline Phase ◽  
Wave Number ◽  
Test Results ◽  
X Ray Diffraction ◽  
X Ray ◽  
Oxide Characteristics

<pre>Calcium oxide (CaO) and calcium carbonate (CaCO3) are widely used in industry. CaO and CaCO3 can be synthesized or derived from limestone. The purpose of this study to determine the characteristics of CaO calcined limestone from Ambunten Sumenep. Lime in calcined at 850 ° C for 6 hours. Characterization of X-ray fluorescence (XRF) was conducted to determine the chemical composition of limestone, X-ray diffraction test (XRD) to find the lime crystalline phase and FTIR test to determine the absorption of wave number. XRF test results showed that the limestone chemical composition consisted of Ca of 95.37% as the dominant element, Mg of 4.1%, Fe 0.17% and Y by 0.39%. The XRD test results showed that the limestone crystal phase is ankerite (Ca [Fe, Mg] [CO3] 2) and after the calcined phase calcination is vaterite (Ca [OH] 2), calcite (CaO) and calcite (CaCO3). While the FTIR test results show that the CaO spectra are seen at 3741.24, 1417.12 and 874.14 cm</pre><sup>-1</sup><pre>.</pre>

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