Influence of the partial substitution of fine aggregate by granite powder in mortar on the process of natural carbonation

2019 ◽  
Vol 38 (3) ◽  
pp. 254-262 ◽  
Author(s):  
Júlio Lopes da Silva ◽  
Daniel Baracuy da Cunha Campos ◽  
Alberto Casado Lordsleem ◽  
Yeda Vieira Povoas
Keyword(s):  
Particle Size ◽  
Exposure Time ◽  
Time Variable ◽  
Partial Substitution ◽  
Fine Aggregate ◽  
Carbonation Depth ◽  
Experimental Planning ◽  
Carbonation Process ◽  
Granite Powder ◽  
Natural Carbonation

This article presents an evaluation of the influence on the natural carbonation process of the use of granite cutting residue as a replacement for fine aggregate in mortars. The methodology adopted consisted of replacing the fine aggregate with granite cutting residue, analysing the carbonation depth with the aid of an experimental planning matrix of 23 + 3 repetitions at the central point. The influence of the exposure time, the percentage of residue in the mixture, and the particle size of the residue used were evaluated. The exposure time variable was found to have the greatest influence on the carbonation process. Under the conditions analysed, granite residue was found to be beneficial, reducing the carbonation depth.

scholarly journals Predicting Carbonation Depth of Prestressed Concrete under Different Stress States Using Artificial Neural Network

2009 ◽  
Vol 2009 ◽  
pp. 1-8 ◽  
Author(s):  
Chunhua Lu ◽  
Ronggui Liu
Keyword(s):  
Neural Network ◽  
Stress Level ◽  
Prestressed Concrete ◽  
Back Propagation ◽  
Back Propagation Neural Network ◽  
Fine Aggregate ◽  
Carbonation Depth ◽  
Carbonation Process ◽  
Artificial Neural ◽  
Stress States

Two artificial neural networks (ANN), back-propagation neural network (BPNN) and the radial basis function neural network (RBFNN), are proposed to predict the carbonation depth of prestressed concrete. In order to generate the training and testing data for the ANNs, an accelerated carbonation experiment was carried out, and the influence of stress level of concrete on carbonation process was taken into account especially. Then, based on the experimental results, the BPNN and RBFNN models which all take the stress level of concrete, water-cement ratio, cement-fine aggregate, cement-coarse aggregate ratio and testing age as input parameters were built and all the training and testing work was performed in MATLAB. It can be found that the two ANN models seem to have a high prediction and generalization capability in evaluation of carbonation depth, and the largest absolute percentage errors of BPNN and RBFNN are 10.88% and 8.46%, respectively. The RBFNN model shows a better prediction precision in comparison to BPNN model.

Processing of granite quarry solid waste into industrial high silica materials using leaching process with HCl concentration variation

2020 ◽  
Vol 11 (2) ◽  
pp. 43-50
Author(s):  
Yusup Hendronursito ◽  
Muhammad Amin ◽  
Slamet Sumardi ◽  
Roniyus Marjunus ◽  
Frista Clarasati ◽  
...  
Keyword(s):  
Particle Size ◽  
Rotational Speed ◽  
Inductively Coupled Plasma ◽  
Chemical Elements ◽  
Silica Content ◽  
X Ray ◽  
Concentration Variation ◽  
Leaching Process ◽  
Hcl Concentration ◽  
Granite Powder

This study was aimed to increase granite's silica content using the leaching process with HCl concentration variation. The granite used in this study came from Lematang, South Lampung. This study aims to determine the effect of variations in HCl concentration, particle size, and rotational speed on the crystalline phase and chemical elements formed in the silica product produced from granite. The HCl concentration variations were 6.0 M, 7.2 M, 8.4 M, and 9.6 M, the variation in particle size used was 270 and 400 mesh. Variations in rotational speed during leaching were 500 and 750 rpm. Granite powder was calcined at 1000 ºC for 2 hours. Characterization was performed using X-Ray Fluorescence (XRF), X-Ray Diffraction (XRD), and Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP- OES). The results showed that the silica content increased with increasing HCl concentration, the finer the particle size, and the higher the rotational speed. XRF analysis showed that the silica with the highest purity was leached with 9.6 HCl with a particle size of 400 mesh and a rotational speed of of 750 rpm, which was 73.49%. Based on the results above, by leaching using HCl, the Si content can increase from before. The XRD diffractogram showed that the granite powder formed the Quartz phase.

scholarly journals Influencing Factors of the Mineral Carbonation Process of Iron Ore Mining Waste in Sequestering Atmospheric Carbon Dioxide

2021 ◽  
Vol 13 (4) ◽  
pp. 1866
Author(s):  
Noor Allesya Alis Ramli ◽  
Faradiella Mohd Kusin ◽  
Verma Loretta M. Molahid
Keyword(s):  
Carbon Dioxide ◽  
Particle Size ◽  
Chemical Composition ◽  
Iron Ore ◽  
Divalent Cations ◽  
Mining Industry ◽  
Mining Waste ◽  
Aluminum Silicate ◽  
Mineral Carbonation ◽  
Carbonation Process

Mining waste may contain potential minerals that can act as essential feedstock for long-term carbon sequestration through a mineral carbonation process. This study attempts to identify the mineralogical and chemical composition of iron ore mining waste alongside the effects of particle size, temperature, and pH on carbonation efficiency. The samples were found to be alkaline in nature (pH of 6.9–7.5) and contained small-sized particles of clay and silt, thus indicating their suitability for mineral carbonation reactions. Samples were composed of important silicate minerals needed for the formation of carbonates such as wollastonite, anorthite, diopside, perovskite, johannsenite, and magnesium aluminum silicate, and the Fe-bearing mineral magnetite. The presence of Fe2O3 (39.6–62.9%) and CaO (7.2–15.2%) indicated the potential of the waste to sequester carbon dioxide because these oxides are important divalent cations for mineral carbonation. The use of small-sized mine-waste particles enables the enhancement of carbonation efficiency, i.e., particles of <38 µm showed a greater extent of Fe and Ca carbonation efficiency (between 1.6–6.7%) compared to particles of <63 µm (0.9–5.7%) and 75 µm (0.7–6.0%). Increasing the reaction temperature from 80 °C to 150–200 °C resulted in a higher Fe and Ca carbonation efficiency of some samples between 0.9–5.8% and 0.8–4.0%, respectively. The effect of increasing the pH from 8–12 was notably observed in Fe carbonation efficiency of between 0.7–5.9% (pH 12) compared to 0.6–3.3% (pH 8). Ca carbonation efficiency was moderately observed (0.7–5.5%) as with the increasing pH between 8–10. Therefore, it has been evidenced that mineralogical and chemical composition were of great importance for the mineral carbonation process, and that the effects of particle size, pH, and temperature of iron mining waste were influential in determining carbonation efficiency. Findings would be beneficial for sustaining the mining industry while taking into account the issue of waste production in tackling the global carbon emission concerns.

scholarly journals Synthesis of magnesium carbonate hydrate from natural talc

2020 ◽  
Vol 18 (1) ◽  
pp. 951-961
Author(s):  
Qiuju Chen ◽  
Tao Hui ◽  
Hongjuan Sun ◽  
Tongjiang Peng ◽  
Wenjin Ding
Keyword(s):  
Crystal Structure ◽  
Particle Size ◽  
Crystal Growth ◽  
Crystal Morphology ◽  
Magnesium Carbonate ◽  
Organic Additives ◽  
X Ray Diffraction ◽  
Morphological Transformation ◽  
X Ray ◽  
Carbonation Process

AbstractVarious morphologies of magnesium carbonate hydrate had been synthesized without using any organic additives by carefully adjusting the reaction temperature and time during the talc carbonation process. At lower temperatures, magnesium carbonate hydrate was prone to display needle-like morphology. With the further increase of the carbonation temperature, the sheet-like crystallites became the preferred morphology, and at higher aging temperatures, these crystallites tended to assemble into layer-like structures with diverse morphologies, such as rose-like particles and nest-like structure. The reaction time had no effect on the crystal morphology, but it affected the particle size and situation of the crystal growth. X-Ray diffraction results showed that these various morphologies were closely related to their crystal structure and compositions. The needle-like magnesium carbonate hydrate had a formula of MgCO3·3H2O, whereas with the morphological transformation from needle-like to sheet-like, rose-like, and nest-like structure, their corresponding compositions also changed from MgCO3·3H2O to 4MgCO3·Mg(OH)2·8H2O, 4MgCO3·Mg(OH)2·5H2O, and 4MgCO3·Mg(OH)2·4H2O.

scholarly journals Identification and analysis of pathological defect appearance in superstructures of reinforced-concrete bridges in Chapare region, Bolivia

DYNA ◽  
2021 ◽  
Vol 88 (216) ◽  
pp. 15-21
Author(s):  
Joaquin Humberto Aquino Rocha ◽  
Rolando Ibarra Villanueva
Keyword(s):  
Visual Inspection ◽  
Structural Characteristics ◽  
Concrete Bridges ◽  
High Humidity ◽  
Carbonation Depth ◽  
Carbonation Process ◽  
Reinforced Concrete Bridges ◽  
Inspection And Maintenance ◽  
Core Extraction ◽  
Selection Of

The objective of this article is to identify and analyze the main pathological manifestations in bridges in the Chapare - Bolivia region, an area characterized by high humidity and constant rainfall throughout the year. The methodology consisted of the selection of five bridges that showed evident signs of deterioration, in which a visual inspection was carried out and, subsequently, different tests: sclerometer, carbonation depth, penetration of chlorides and core extraction. All the bridges present advanced states of deterioration; highlighting corrosion as the main problem, generating detachment of the concrete and risk of collapse. Although the concrete has a compression strength greater than 30 MPa, the existing carbonation process and the different problems encountered compromises it. It is necessary that the entities in charge provide inspection and maintenance programs according to the environmental and structural characteristics of each bridge.

Effect of Several Factors on the Synthesis of Calcium Hydroxide Prepared by Spray Drying Method Using Limestone

2007 ◽  
Vol 544-545 ◽  
pp. 733-736
Author(s):  
Moon Kwan Choi ◽  
Jin Sang Cho ◽  
Sung Min Joo ◽  
Jin Koo Park ◽  
Ji Whan Ahn ◽  
...  
Keyword(s):  
Particle Size ◽  
Calcium Carbonate ◽  
Spray Drying ◽  
Feeding Rate ◽  
Spherical Shape ◽  
Initial Reaction ◽  
Outlet Temperature ◽  
Drying Method ◽  
Precipitated Calcium Carbonate ◽  
Carbonation Process

The purpose of this work is to influence of CaO concentrations of 5.0 wt.% and 10.0 wt.%, slurry feeding rate of 200~400 /min, rotating rate of drum of 5,000 and 10,000 rpm, inlet and outlet temperature on the synthesis of Ca(OH)2 powder, and the synthesis of precipitated calcium carbonate by carbonation process using Ca(OH)2 prepared by spray drying method. As the feeding rate of slurry was increased, the particle size of Ca(OH)2 was decreased. Regardless of rotating rate of drum, when the concentration of CaO was 5.0 wt.% and 10.0 wt.%, the morphology of Ca(OH)2 showed spherical shape of 10~30 μm and 20~60 μm, respectively. The specific surface area of synthesized Ca(OH)2 was 27~30 m2/g. When the initial reaction temperature was 11 °C and 30 °C, the shape and particle size of precipitated calcium carbonate synthesized in the carbonation process showed the rectangular shape of 0.1~0.4 μm and the spindle shape of 0.5~1.0 μm, respectively.

scholarly journals Eco-friendly microwave-enhanced green synthesis of silver nanoparticles using Aloe vera leaf extract and their physico-chemical and antibacterial studies

2018 ◽  
Vol 7 (3) ◽  
pp. 231-240 ◽  
Author(s):  
Omid Ahmadi ◽  
Hoda Jafarizadeh-Malmiri ◽  
Naeimeh Jodeiri
Keyword(s):  
Particle Size ◽  
Silver Nanoparticles ◽  
Exposure Time ◽  
Leaf Extract ◽  
Aloe Vera ◽  
Synthesis Conditions ◽  
Stabilizing Agents ◽  
Microwave Exposure ◽  
Mean Particle Size ◽  
Vis Spectroscopy

Abstract Silver nanoparticles (AgNPs) were synthesized using Aloe vera leaf extract as both reducing and stabilizing agents via microwave irradiation method. The effects of the microwave exposure time and the amount of AgNO3 solution on the mean particle size and concentration of the synthesized AgNPs solution were investigated using response surface methodology. The synthesized AgNPs were characterized by transmission electron microscopy, UV-Vis spectroscopy, and dynamic light scattering. Well-dispersed and spherically fabricated AgNPs with mean particle size (46 nm) and maximum concentration (64 ppm) and zeta potential (+15.5 mV), were obtained at optimal synthesis conditions, using 9 ml of AgNO3 (1 mm) and 0.1 ml of Aloe vera extract during microwave exposure time of 360 s. The antibacterial activity of the synthesized AgNPs was tested using Escherichia coli and Staphylococcus aureus bacteria and the obtained results indicated their significant inhibitory effects against these two Gram-negative and Gram-positive bacteria.

scholarly journals Review of Carbonation Resistance in Hydrated Cement Based Materials

2019 ◽  
Vol 2019 ◽  
pp. 1-6 ◽  
Author(s):  
Joseph Mwiti Marangu ◽  
Joseph Karanja Thiong’o ◽  
Jackson Muthengia Wachira
Keyword(s):  
Environmental Benefits ◽  
Partial Substitution ◽  
Cement Matrix ◽  
Hardened Cement ◽  
Hydrated Cement ◽  
Blended Cements ◽  
Carbonation Process ◽  
Carbonation Resistance ◽  
Cement Based Materials ◽  
Process Factors

Blended cements are preferred to Ordinary Portland Cement (OPC) in construction industry due to costs and technological and environmental benefits associated with them. Prevalence of significant quantities of carbon dioxide (CO2) in the atmosphere due to increased industrial emission is deleterious to hydrated cement materials due to carbonation. Recent research has shown that blended cements are more susceptible to degradation due to carbonation than OPC. The ingress of CO2 within the porous mortar matrix is a diffusion controlled process. Subsequent chemical reaction between CO2 and cement hydration products (mostly calcium hydroxide [CH] and calcium silicate hydrate [CSH]) results in degradation of cement based materials. CH offers the buffering capacity against carbonation in hydrated cements. Partial substitution of OPC with pozzolanic materials however decreases the amount of CH in hydrated blended cements. Therefore, low amounts of CH in hydrated blended cements make them more susceptible to degradation as a result of carbonation compared to OPC. The magnitude of carbonation affects the service life of cement based structures significantly. It is therefore apparent that sufficient attention is given to carbonation process in order to ensure resilient cementitious structures. In this paper, an indepth review of the recent advances on carbonation process, factors affecting carbonation resistance, and the effects of carbonation on hardened cement materials have been discussed. In conclusion, carbonation process is influenced by internal and external factors, and it has also been found to have both beneficial and deleterious effects on hardened cement matrix.

The Effect of Silica Fused Addition as Filler on Zircon Based Refractory Coating

2020 ◽  
Vol 988 ◽  
pp. 23-29
Author(s):  
Davino Aditya Dwinanda ◽  
Donanta Dhaneswara ◽  
Bionolla Shandiana
Keyword(s):  
Particle Size ◽  
Simultaneous Thermal Analysis ◽  
Casting Process ◽  
Particle Size Analysis ◽  
Partial Substitution ◽  
Size Analysis ◽  
Refractory Coating ◽  
Alternative Material ◽  
Thermal Stability Of

Refractory coating is widely used in metal casting process to protect the mold from direct contact with molten metal. This coating also could improve the surface quality of casting product. Zircon is common materials that used as filler, but the materials cost is quite high. Therefore, alternative material is needed to make partial substitution of the filler. Silica Fused can be considered as filler because it has good refractoriness. This study aims to determine silica fused is reliable as an alternative to substitute zircon filler. The samples were made with 16%, 18%, and 20% silica fused addition and different treatment which were heated and non-heated drying. Particle size and distributions of the filler were analyzed using Particle Size Analysis. Viscosity measurement has been done to coating slurry to analyze the rheological characteristics of the slurry. The surface morphology of dried coating was taken using Scanning Electron Microscope. XRD test also has been done to analyse the compound. The quality of coating was determined from the thermal stability of the coating that was analyzed using Simultaneous Thermal Analysis. The result shows that silica fused is reliable as an alternative material for filler partial substitution.

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