scholarly journals MICROSCOPIC FEATURES OF CEMENT PASTE MODIFIED BY FINE PERLITE

2016 ◽  
Vol 7 ◽  
pp. 12
Author(s):  
Vladimír Hrbek ◽  
Veronika Koudelková ◽  
Pavel Padevět ◽  
Petr Šašek
Keyword(s):  
Electron Microscopy ◽  
Construction Industry ◽  
Lightweight Aggregate ◽  
Cement Matrix ◽  
Instrumented Indentation ◽  
Cement Sample ◽  
Cement Material ◽  
Material Development ◽  
Microscopic Features ◽  
Cement Binder

The use of waste material and replacement of binder element in cementitious composites is in focus of material development. Perlite in the construction industry is usually used in form of lightweight aggregate enhancing the insulating performance of concrete. This paper focuses on integration of fine perlite into the cement matrix and possible replacement of the cement binder in the composition of the material. The macromechanical performance of the modified paste is tested on specimens with 5, 10, 15 and 20% fine perlite substitution and pure cement sample. To distinguish the effect of the perlite on the microstructural level, pure cement material and specimen containing 10% of fine perlite are investigated by the electron microscopy. Furthermore, the mechanical properties of individual phases are examined and compared on same samples by instrumented indentation. The presented results enabled estimation of fine perlite impact on the macro and microscopic performance of the material.

Study on Preparation of a New Foamed Cement Material

2013 ◽  
Vol 648 ◽  
pp. 104-107
Author(s):  
Chuan Wei Du ◽  
Guo Zhong Li
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Fly Ash ◽  
Ordinary Portland Cement ◽  
Raw Materials ◽  
Lightweight Aggregate ◽  
Foaming Agent ◽  
Cement Material ◽  
Foam Stabilizer ◽  
Scanning Electron

The ordinary Portland cement as matrix materials and fly ash as a lightweight aggregate were used to prepare a new foamed cement material by chemical foaming method though adding a proper level of foaming agent, foam stabilizer, and glass fiber. The raw materials’ ratio of new foamed cement was determined through the experiment. The microstructure of bubble was analysed by electronic scanning electron microscopy. The mechanism of foam stabilizer and fiber reinforced mechanisms were explored.

scholarly journals Features of the hydration process of the modified blended cement for fiber cement panels

2018 ◽  
Vol 170 ◽  
pp. 03030 ◽  
Author(s):  
Rustem Mukhametrakhimov ◽  
Liliya Lukmanova
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Blended Cement ◽  
Physical And Mechanical Properties ◽  
Hydration Process ◽  
Cement Matrix ◽  
X Ray Diffraction ◽  
Structure Form ◽  
Silicate Phase ◽  
X Ray

The paper studies features of the hydration process of the modified blended cement for fiber cement panels (FCP) using differential thermal analysis, X-ray diffraction analysis, electron microscopy and infrared spectroscopy. It is found that deeper hydration process in silicate phase, denser and finer crystalline structure form in fiber cement matrix based on the modified blended cement. Generalization of this result to the case of fiber cement panels makes it possible to achieve formation of a denser and homogeneous structure with increased physical and mechanical properties.

Influence of the Residue of Casting by Lost Wax in the Modulus of Elasticity and Porosity of Concretes

2014 ◽  
Vol 805 ◽  
pp. 343-349
Author(s):  
Carine F. Machado ◽  
Weber G. Moravia
Keyword(s):  
Construction Industry ◽  
Modulus Of Elasticity ◽  
Chemical Characterization ◽  
Microstructural Characterization ◽  
Cement Matrix ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hardened State ◽  
Material Powder

This work evaluated the influence of additions of the ceramic shell residue (CSR), from the industries of Lost Wax Casting, in the modulus of elasticity and porosity of concrete. The CSR was ground and underwent a physical, chemical, and microstructural characterization. It was also analyzed, the environmental risk of the residue. In the physical characterization of the residue were analyzed, the surface area, and particle size distribution. In chemical characterization, the material powder was subjected to testing of X-ray fluorescence (XRF). Microstructural characterization was performed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The residue was utilized like addition by substitution of cement in concrete in the percentages of 10% and 15% by weight of Portland cement. It was evaluated properties of concrete in the fresh and hardened state, such as compressive strength, modulus of elasticity, absorption of water by total immersion and by capillarity. The results showed that the residue can be used in cement matrix and improve some properties of concrete. Thus, the CSR may contribute to improved sustainability and benefit the construction industry.

scholarly journals Size Effect in Compressive Strength Tests of Cored Specimens of Lightweight Aggregate Concrete

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1187 ◽  
Author(s):  
Lucyna Domagała
Keyword(s):  
Compressive Strength ◽  
Scale Effect ◽  
Lightweight Aggregate ◽  
Normal Weight ◽  
Cement Matrix ◽  
Lightweight Aggregate Concrete ◽  
Core Diameter ◽  
Aggregate Concrete ◽  
Normal Weight Concrete ◽  
Strength Tests

The aim of this paper is to discuss the unrecognized problem of the scale effect in compressive strength tests determined for cored specimens of lightweight aggregate concrete (LWAC) against the background of available data on the effect for normal-weight concrete (NWAC). The scale effect was analyzed taking into consideration the influence of slenderness (λ = 1.0, 1.5, 2.0) and diameter (d = 80, 100, 125, and 150 mm) of cored specimens, as well as the type of lightweight aggregate (expanded clay and sintered fly ash) and the type of cement matrix (w/c = 0.55 and 0.37). The analysis of the results for four lightweight aggregate concretes revealed no scale effect in compressive strength tests determined on cored specimens. Neither the slenderness, nor the core diameter seemed to affect the strength results. This fact should be explained by the considerably better structural homogeneity of the tested lightweight concretes in comparison to normal-weight ones. Nevertheless, there were clear differences between the results obtained on molded and cored specimens of the same shape and size.

Influence of Cementitious Capillary Crystalline Waterproofing Material on the Water Impermeability and Microstructure of Concrete

2019 ◽  
Vol 953 ◽  
pp. 209-214
Author(s):  
Yi Teng Zhang ◽  
Lian Zuo ◽  
Jin Chao Yang ◽  
Wei Xia Zhao ◽  
Xiang Xiong Zeng
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Differential Scanning Calorimetry ◽  
Cement Matrix ◽  
Hardened Cement ◽  
Hydration Products ◽  
Hardened Cement Paste ◽  
Scanning Calorimetry ◽  
Chinese Standard ◽  
Scanning Electron

The main objective of this study is to investigate the effect of cementitious capillary crystalline waterproofing (CCCW) material on the water impermeability and microstructure of concrete. The water impermeability of concrete covered with or without CCCW material was tested according to the Chinese standard GB 18445-2012. The results indicate that concretes coated with CCCW material showed much higher water impermeability than blank ones, and the ratio of water impermeability pressure between them reached 275. The samples obtained in various depths of hardened cement paste specimens with or without CCCW coating were analyzed through scanning electron microscopy (SEM) and thermogravimetry-differential scanning calorimetry (TG-DSC), to study the differences in microstructure and hydration products. The results present that after a 28-day standard curing, there were lots of ettringite crystals and CaCO3 formed in the paste in 1 cm from the coating, but the action depth of the CCCW coating could not reach 3 cm. The ettringite and CaCO3 is precipitated in the pore structure of cement matrix and filling the voids, which leads to the significant enhancement in water impermeability.

Methodology for the determination of <63 µm free mica fines in sand and within the cement matrix of hardened concrete blocks using scanning electron microscopy and energy dispersive spectroscopy

2019 ◽  
Vol 53 (3) ◽  
pp. 425-430
Author(s):  
Leona O'Connor ◽  
Robbie Goodhue
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Resolution ◽  
Energy Dispersive Spectroscopy ◽  
Cement Matrix ◽  
Hardened Concrete ◽  
Concrete Blocks ◽  
Free Mica ◽  
Supplementary Material ◽  
Scanning Electron

We propose a method for quantification of the percentage of <63 µm muscovite fines (termed free mica) in mixed sand fines and the identification/semi-quantitative analysis of free mica in the cement matrix of hardened concrete blocks. In recent times homeowners in County Donegal, Ireland reported structural problems in their buildings and concern that it is due to high concentrations of free mica within the concrete blocks. Our method requires the generation of high-resolution backscattered electron (BSE) images using field emission scanning electron microscopy (FE-SEM), where the characteristic needle-like morphology of mica can easily be identified. Additional information on the size, shape and chemical composition of the free mica fines, is gathered using energy dispersive spectroscopy (EDS or EDX). The combination of high-magnification images, high-resolution elemental maps, and mineral liberation software allows accurate identification and quantification of free mica within the sand fines and cement matrix.Supplementary material: Information pertaining to the measurements by SEM-EDX are reported in Supplementary Tables 1 and 2, available at https://doi.org/10.6084/m9.figshare.c.4709390

Flexural and shear strengths of fiber modify lightweight aggregate concrete and its application in water-retaining structures

2017 ◽  
Vol 14 (2) ◽  
pp. 101-107 ◽  
Author(s):  
Adnan Qadir ◽  
Uneb Gazder
Keyword(s):  
Construction Industry ◽  
Control Sample ◽  
Lightweight Aggregate ◽  
Target Strength ◽  
Lightweight Aggregate Concrete ◽  
Water Tank ◽  
Loading Test ◽  
Retaining Structures ◽  
Aggregate Concrete ◽  
Content Type

Purpose The purpose of this study is to investigate the incorporation of lightweight aggregate concrete modify with fiber (LWACF) in water retaining structure. In developed countries LWACF is being successfully used as structural concrete; however, third-world countries such as Pakistan are still struggling to come up with the practical applications of lightweight concrete in the building and construction industry. One reason is because of the lack of reliable data regarding its performance as a structural member in the building and construction industry. Design/methodology/approach The present study inspected the flexural and shear tolerance of fiber-reinforced LWACF by testing six beam specimens’ cast, cured and tested after 28 days for the purpose. An overhead tank of 1,000-gallon capacity was also constructed to verify the application of LWACF by observing its water retention behavior. The experimental design included a mix design of concrete at a target strength of 21 MPa for control sample natural aggregate and for synthetic aggregate modified with polypropylene fibers. Compressive strengths of both categories of concrete were also determined by crushing the cylindrical samples at the age of 7, 14, 21 and 28 days. The cast beams were later subjected to the application of two-point loading test until failure. Findings It was found that the beams fabricated with LWACF possessed better resistance to cracks compared with those fabricated with normal weight concrete, both in terms of number and crack width. The study also concluded that the constructed water tank with LWACF was thermally efficient and structurally sound, as it showed no sign of seepage for the observed period. Originality/value On the basis of the results, it can be concluded that the LWACF used has revolutionized the concept of using lightweight aggregates in regular structures and that consequently it will help in a constructing a sustainable environment. One of the useful applications of such material is for water-retaining structures.

scholarly journals General morphology of the oral cavity of the Nile crocodile, Crocodylus niloticus (Laurenti, 1768). I. Palate and gingivae

2003 ◽  
Vol 70 (4) ◽  
Author(s):  
J.F. Putterill ◽  
J.T. Soley
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Connective Tissue ◽  
Taste Receptors ◽  
General Morphology ◽  
Histological Features ◽  
Microscopic Features ◽  
Sensory Structures ◽  
Nile Crocodile ◽  
Scanning Electron

The heads of nine 2.5 to 3-year-old Nile crocodiles (Crocodylus niloticus) were obtained from a commercial farm where crocodiles are raised for their skins and meat. The animals from which these specimens originated were clinically healthy at the time they were slaughtered. A detailed description of the macroscopic and microscopic features of the palate and gingivae of the Nile crocodile is presented and the results are compared with published information on this species and other Crocodylia. The histological features are supplemented by information supplied by scanning electron microscopy. Macroscopic features of interest are the small conical process situated at the base of the first two incisors of the maxilla, the distribution of cobbled units on the palate, and the broad dentary shelf forming the rostral aspect of the mandible. Histologically the palate and gingivae did not differ significantly from each other and both regions showed a presence of Pacinian-type corpuscles. Two types of sensory structures (taste receptors and pressure receptors) were identified in the regions examined, both involving modification of the epithelium and the underlying connective tissue.

Microscopic Features of Mudstone Based on SEM Images

2013 ◽  
Vol 353-356 ◽  
pp. 1130-1135
Author(s):  
Liu Sheng Pan ◽  
Ru Cheng Zhou
Keyword(s):  
Electron Microscopy ◽  
Structural Features ◽  
Engineering Properties ◽  
Shape Parameters ◽  
Sem Images ◽  
Canny Edge Detection ◽  
Inscribe Circle ◽  
Microscopic Features ◽  
Canny Edge ◽  
Scanning Electron

Microstructure features have a significant effect on the engineering properties of geomaterials. In the current study, the images of the mudstone samples were obtained using the Scanning Electron Microscopy (SEM) technique. After converted the original images into the grayscale and binary ones, the Canny edge detection technique was utilized to detect the particle edges and compute the characteristic shape parameters of the particles in the SEM images, including the eccentricity, flat circular degree, circular degree, discrete index, radius of inscribe circle. The analysis of correlation between these shape parameters was thereafter performed. All of the above processings was implemented using the MATLAB platform. It shows that some parameters, such as eccentricity and anisotropic rate, had a great correlation; and other parameters, such as perimeter and discrete index, had a good correlation; some parameters, such as anisotropic rate and area, had no correlation. The methods presented herein may be referable in investigating the structural features and deformation/failure mechanism of the mudstones in various scales.

scholarly journals BEACHROCKS CEMENT CHARACTERISTICS AND CONDITIONS OF FORMATION. CASE STUDY PLATANIAS BEACH, CHANIA, GREECE

2017 ◽  
Vol 50 (1) ◽  
pp. 458
Author(s):  
A. Petropoulos ◽  
I. Baziotis ◽  
Ch. Anagnostou ◽  
N. Evelpidou
Keyword(s):  
Electron Microscopy ◽  
Raman Spectroscopy ◽  
Optical Microscopy ◽  
Secondary Electron ◽  
Coastal Sediment ◽  
Intertidal Area ◽  
Cement Material

Beachrocks represents a coastal deposition in the intertidal area, and studying their properties may lead to create a model which identifies the conditions of their formation (paleo-environment). This paper focuses most intently on the cement material which is able to recover the paleo-environment conditions during diagenesis of such coastal sediment. We used optical microscopy, secondary electron microscopy and Raman Spectroscopy to characterize the cement texture, mineralogy and chemistry in the beachrocks. The existence of pure calcite primarily controlled by the meteorite water, while Mg-calcite appears between the lowermeteoric and the upper marine phreatic zone. Finally, the presence of aragonite associated with the marine phreatic to lower marine vadose environment.

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