scholarly journals Performance of ANN in Predicting Internal Bonding of Cement Particleboard Manufactured from Giant Reed and Bagasse

2021 ◽  
Vol 72 (3) ◽  
pp. 255-271
Author(s):  
Morteza Nazerian ◽  
Hossin Assadolahpoor Nanaii ◽  
Elham Vatankhah ◽  
Mojtaba Koosha
Keyword(s):  
Cement Paste ◽  
Bonding Strength ◽  
Microstructural Analysis ◽  
Giant Reed ◽  
Hardened Cement ◽  
Data Sets ◽  
Internal Bonding ◽  
Cement Pastes ◽  
Coeffi Cients ◽  
Artificial Neural Network Ann

The present article investigates the microstructure of the cement matrices and the products of cement hydration by means of scanning electron microscopy, Fourier transform infrared spectroscopy and X-Ray diffraction. Then, the internal bonding strength (IB) is measured for the mixtures containing various amounts of nanosilica (NS), reed and bagasse particles. Finally, an Artificial Neural Network (ANN) is trained to reproduce these experimental results. The results show that the hardened cement paste including NS features the highest level of C-S-H. However, it has a lower level of C-S-H polymerization if reed or bagasse particles are applied. A relatively new dense microstructural degree is considered in the cement pastes containing NS, and a lower agglomeration is observed in the samples including reed or bagasse particles with NS. According to the microstructural analysis, the addition of NS to the samples containing reed or bagasse particles increases the unhydrated amount of C2S and C3S in the cement paste due to the decrease in the water needed for fully hydrated cement grains through portlandite (Ca(OH)2), C-S-H and ettringite increase. Besides, it is shown that the ANN prediction model is a useful, reliable and quite effective tool for modeling IB of cement-bonded particleboard (CBPB). It is indicated that the mean absolute percentage errors (MAPE) are 1.98 % and 1.45 % in the prediction of the IB values for the training and testing datasets, respectively. The determination coeffi cients (R2) of the training and testing data sets are 0.972 and 0.997 in the prediction of the bonding strength by ANN, respectively.

Porosity and Ion Diffusivity of Latex-Modified Cement

1989 ◽  
Vol 176 ◽  
Author(s):  
Takashi Nishi ◽  
Osamu Kuriyama ◽  
Masami Matsuda ◽  
Koichi Chino ◽  
Makoto Kikuchi
Keyword(s):  
Pore Water ◽  
Cement Paste ◽  
Nuclear Power ◽  
Power Plants ◽  
Total Porosity ◽  
Bulk Water ◽  
Hardened Cement ◽  
Cement Pastes ◽  
Water Proof ◽  
Cs Ions

ABSTRACTLatex-modified Portland cement, which would be expected to have low permeability and ion diffusivity, was studied for possible application as a solidification agent for radioactive wastes generated from nuclear power plants. In order to predict the leaching ratio of radionuclides from the cementitious waste forms, the effect of water and latex content in the fresh cement paste on total porosity and ion diffusivity of hardened paste was quantitatively estimated.Total porosity of hardened cement paste decreased with the reduction of water content in the fresh paste and it was also reduced by latex addition. This latter effect could be attributed to the latex emulsion forming a water-proof film and filling the capillary pores. Also Cs ions diffusivity, which is the ratio of the diffusion coefficient in pore water to that in bulk water, showed an exponential correlation with total porosity for both cement materials. An empirical equation, expressing ion diffusivity as a function of total porosity, was derived from the consideration that the water constrictivity in this porous medium could cause an increase of the apparent viscosity of pore water. These results suggested a possibility that the transport behavior of radionuclides through the cementitious matrix could be estimated from the mixing parameters of the original cement pastes.

An Investigation Of A High Speed Shear Mixer On Selected Pastes And Mortars

1988 ◽  
Vol 137 ◽  
Author(s):  
M. L. Brown ◽  
W. B. Ledbetter ◽  
H. M. Jennings
Keyword(s):  
Cement Paste ◽  
High Speed ◽  
Initial Study ◽  
Hardened Cement ◽  
Hardened Cement Paste ◽  
Cement Pastes ◽  
Shear Mixing ◽  
Paddle Mixer

AbstractThe influence of shear mixing on selected properties of cement pastes and mortars was investigated by preparing specimens using an ordinary paddle mixer and a high speed shear mixer. The results appear to indicate that shear mixing influences the bond between paste and aggregate, particularily at low water:cement ratios. The properties of hardened cement paste did not change markedly as a result of high speed shear mixing used in this initial study.

The Relationship between the Strength and the Pore Structures of Cement Paste with Mineral Admixtures

2011 ◽  
Vol 250-253 ◽  
pp. 104-108 ◽  
Author(s):  
Yue Li ◽  
Jun Ling Bao ◽  
Chun E Sui ◽  
Xiu Li Du
Keyword(s):  
Compressive Strength ◽  
Pore Structure ◽  
Cement Paste ◽  
Mapping Function ◽  
Mineral Admixtures ◽  
Hardened Cement ◽  
Cement Pastes ◽  
Binder Ratio ◽  
Water To Binder Ratio ◽  
The Relationship

This paper presents the effects of mineral admixtures and the water to binder ratio (W/B) on the tensile and compressive strength and micro pore structure of hardened cement pastes. The test results show that: with the water to binder ratio increasing, the tensile and compressive strength of cement paste with different mineral admixtures will decrease, air content and mean pore diameter will decrease and the cement paste with the ground blast furnace slag is the lowest. The artificial neural network based on its nonlinear mapping function can fit the relationship between strength and pore structure more accurate than an empirical formula.

scholarly journals On Phase Identification of Hardened Cement Pastes by Combined Nanoindentation and Mercury Intrusion Method

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3349
Author(s):  
Jingwei Ying ◽  
Xiangxin Zhang ◽  
Zhijun Jiang ◽  
Yijie Huang
Keyword(s):  
Mechanical Properties ◽  
Pore Structure ◽  
Cement Paste ◽  
Phase Distribution ◽  
Gaussian Mixture ◽  
Hardened Cement ◽  
Phase Identification ◽  
Hardened Cement Paste ◽  
Cement Pastes ◽  
Mercury Intrusion

The micro-mechanical properties of hardened cement paste can be obtained by nanoindentation. Phases at different locations can generally be determined by using the Gaussian mixture model (GMM) method and the K-means clustering (KM) method. However, there are differences between analysis methods. In this study, pore structure and porosity of hardened cement paste aged three, seven, and 28 days were obtained by mercury intrusion porosimetry (MIP), and their micro-mechanical properties were obtained by the nanoindentation method. A new method, GMM-MIP and KM-MIP, was proposed to determine the phase of hardened cement paste based on the pore structure and nanoindentation results. The results show that GMM-MIP and KM-MIP methods are more reasonable than GMM and KM methods in determining the phase of hardened cement paste. GMM-MIP can be used to obtain reasonable phase distribution. If the micro-mechanical properties of each phase in hardened cement paste do not satisfy the normal distribution, the GMM method has significant defects.

scholarly journals DISTRIBUTION OF HYDRATION PRODUCTS IN THE MICROSTRUCTURE OF CEMENT PASTES

2020 ◽  
Vol 27 ◽  
pp. 84-89
Author(s):  
Michal Hlobil
Keyword(s):  
Compressive Strength ◽  
Cement Paste ◽  
Numerical Study ◽  
Hardened Cement ◽  
Spatial Gradient ◽  
Hydration Products ◽  
Hardened Cement Paste ◽  
Cement Pastes ◽  
Hydration Model

This case study focuses on the quantification of the amorphous hydrate distribution in the microstructure of hardened cement paste. Microtomographic scans of the hardenend cement paste were thresholded based on histogram image analysis combined with microstructural composition obtained from CEMHYD3D hydration model, to separate unhydrated cement grains, crystalline and amorphous hydrates, and capillary pores. The observed spatial distribution of the amorphous hydrate exhibited a strong spatial gradient as the amorphous gel tended to concentrate around dissolving cement grains rather than precipitate uniformly in the available space. A comparative numerical study was carried out to highlight the effect of the spatially (non)uniform hydrate distribution on the compressive strength of the hardened cement paste.

scholarly journals The Influence of Fluidized Bed Combustion Fly Ash on the Phase Composition and Microstructure of Cement Paste

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2838
Author(s):  
Michał A. Glinicki ◽  
Daria Jóźwiak-Niedźwiedzka ◽  
Mariusz Dąbrowski
Keyword(s):  
Phase Composition ◽  
Fly Ash ◽  
Fluidized Bed ◽  
Cement Paste ◽  
Power Plants ◽  
Circulating Fluidized Bed ◽  
Thermal Analyses ◽  
Hardened Cement ◽  
Fluidized Bed Combustion ◽  
Cement Pastes

Fly ashes from coal combustion in circulating fluidized bed boilers in three power plants were tested as a potential additive to cement binder in concrete. The phase composition and microstructure of cement pastes containing fluidized bed fly ash was studied. The fractions of cement substitution with fluidized bed fly ash were 20% and 30% by weight. X-ray diffraction (XRD) tests and thermal analyses (derivative thermogravimetry (DTG), differential thermal analysis (DTA) and thermogravimetry (TG)) were performed on ash specimens and on hardened cement paste specimens matured in water for up to 400 days. Quantitative evaluation of the phase composition as a function of fluidized bed fly ash content revealed significant changes in portlandite content and only moderate changes in the content of ettringite.

Hydration and Microstructure of Nano Modified Cement Paste

2021 ◽  
Vol 321 ◽  
pp. 9-14
Author(s):  
Gintautas Skripkiūnas ◽  
Ekaterina Karpova ◽  
Rostislav Drochytka ◽  
Jakub Hodul
Keyword(s):  
Cement Paste ◽  
Cement Hydration ◽  
Aqueous Suspension ◽  
Hardened Cement ◽  
Hardened Cement Paste ◽  
Cement Pastes ◽  
Microstructure Observation ◽  
Multi Walled Carbon Nanotubes ◽  
Hardened Cement Pastes ◽  
Walled Carbon Nanotubes

Hydration of cement systems modified by nano additives requires the understanding of its mechanisms. The present research is focused on the investigation of hydration processes in cement pastes modified by multi-walled carbon nanotubes (MWCNTs) suspension. The ultrasonication method was used for homogenization of MWCNTs in the volume of an aqueous suspension. The hydration of cement pastes was assessed by the calorimetry test. The prolongation of cement hydration in case of modification by MWCNT suspension was observed. The microstructure observation by scanning electron microscopy (SEM) was performed for identification of MWCNT's dispergation in hardened cement pastes and for the observation of cement hydration products. The compressive and flexural strength were tested to evaluate the effect of MWCNT on mechanical properties of hardened cement paste.

scholarly journals Hydration characteristics and structure formation of cement pastes containing metakaolin

2018 ◽  
Vol 149 ◽  
pp. 01013 ◽  
Author(s):  
Leonid Dvorkin ◽  
Nataliya Lushnikova ◽  
Oleksandr Bezusyak ◽  
Mohammed Sonebi ◽  
Jamal Khatib
Keyword(s):  
Pore Structure ◽  
Cement Paste ◽  
Average Diameter ◽  
Cementitious Materials ◽  
Mineral Admixture ◽  
Mineral Admixtures ◽  
Hardened Cement ◽  
Initial Structure ◽  
Hardened Cement Paste ◽  
Cement Pastes

Metakaolin (MK) is one of the most effective mineral admixtures for cement-based composites. The deposits of kaolin clays are wide-spread in the world. Metakaolin is comparable to silica fume as an active mineral admixture for cement-based composites. In this paper, the rheological and mechanical properties of cement paste containing metakaolin are investigated. The effect of MK is more evident at “tight” hydration conditions within mixtures with low water-cement ratio, provided by application of superplasticizers. The cement is replaced with 0 to 15% metakaolin, and superplasticizer content ranged from 0 to 1.5% by weight of cementitious materials (i.e. cement and metakaolin). An equation is derived to describe the relationship between the metakaolin and superplasticizer content and consistency of pastes. There is a linear dependence between metakalolin content and water demand. Second-degree polynomial describe the influence of superplasticizer content. The application of SP and MK may produce cement-water suspensions with water-retaining capacity at 50-70% higher than control suspensions. The investigation of initial structure forming of cement pastes with SP-MK composite admixture indicates the extension of coagulation structure forming phase comparing to the pastes without additives. Crystallization stage was characterized by more intensive strengthening of the paste with SP-MK admixture comparing to the paste without admixtures and paste with SP. Results on the porosity parameters for hardened cement paste indicate a decrease in the average diameter of pores and refinement of pore structure in the presence of metakaolin. A finer pore structure associated with an increase in strength. X-ray analysis data reveal a growing number of small-crystalline low-alkaline calcium hydrosilicates and reducing portlandite content, when MK dosage increases. Scanning electron microscopy (SEM) data confirm, that hardened cement paste containing MK has crystalline structure with dominance of partially crystalized hydrosilicates and gel-like formations.

scholarly journals Effect of co-existing ions on lead leaching behaviour from hardened cement paste

2018 ◽  
Vol 195 ◽  
pp. 01007
Author(s):  
Takumi Nishiwaki ◽  
Shaojun Zhou ◽  
Masaharu Yamasaki ◽  
Yuko Ogawa ◽  
Kenji Kawai
Keyword(s):  
Heavy Metal ◽  
Metal Ions ◽  
Cement Paste ◽  
Heavy Metal Ions ◽  
Chloride Solution ◽  
Hardened Cement ◽  
Leaching Tests ◽  
Cement Pastes ◽  
Lead Leaching ◽  
Cacl2 Solution

Recently, in the concrete field, the use of industrial wastes for concrete materials is expected for environmental reasons. However, these wastes may contain hazardous heavy metals. It is well known that cement paste has an ability to fix heavy metal ions, whereas it was also found that absorbed heavy metal ions can easily leach from cement paste in the presence of a CaCl2 solution. The present study aims to investigate the lead leaching behaviours from hardened cement pastes in various chloride solutions by tank leaching tests. The water-to-cement ratios of the cement paste specimens were 0.40 and 0.55. Lead was added to the cement pastes at 1 mass% of cement. Each chloride solution for the tank leaching test had three kinds of concentrations (5%, 10%, and 20%). After the tank leaching tests, the chemical changes of the specimens were analysed to discuss the effect of co-existing ions in the solutions. The results indicate that the cumulative lead leaching amount is related to the types of chloride solution as well as the concentrations of the solutions. The lead leaching amount in the CaCl2 solution was much higher than that in other solutions.

Rehydration Performance of Binary Binders Made with Dehydrated Cement Paste and Phosphogypsum

2011 ◽  
Vol 474-476 ◽  
pp. 1238-1242 ◽  
Author(s):  
Tao Sun ◽  
Zhong He Shui ◽  
Tao Huo
Keyword(s):  
Cement Paste ◽  
Structural Characteristics ◽  
Setting Time ◽  
Physical And Mechanical Properties ◽  
Hardened Cement ◽  
Initial Water ◽  
Cement Pastes ◽  
Hydrated Calcium Silicate ◽  
Water To Cement Ratio ◽  
Hardened Cement Pastes

This paper presents the rehydration performance of binary binders made with dehydrated cement paste (DCP) and phosphogypsum (GP). DCP was obtained by thermal treatment of hardened cement pastes in which the initial water to cement ratio was 0.5. DCP we mixed with phosphogypsum (PG) to prepare the binary binders . The effect of PG on the physical and mechanical properties of the binary binders was investigated. Scanning electron microscope (SEM) was used to indentify the structural characteristics of the rehydration products. The results showed that the setting time was prolonged and the compressive strength increased slightly by mixing DCP with PG. Microstructural observations indicated that an remarkable amount of ettringite intergrows with the hydrated calcium silicate to form a network structure. Thus, the addition of phosphogypsum can not only utilize the industrial by-product, but enhances the hydraulic properties of the DCP.

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