scholarly journals The Effect of Fly Ash Microspheres on the Pore Structure of Concrete

Minerals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 58 ◽  
Author(s):  
Elzbieta Haustein ◽  
Aleksandra Kuryłowicz-Cudowska
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Total Content ◽  
Spherical Particles ◽  
Hardened Concrete ◽  
Image Analysis System ◽  
Micro Computed Tomography ◽  
Concrete Technology ◽  
Air Voids ◽  
X Ray

The fly ash microspheres (FAMs) formed during the mineral transformation stage in coal combustion are hollow spherical particles with a density less than water. This paper presents the results of X-ray micro-computed tomography and an automatic image analysis system of the porosity in the structure of hardened concrete with microspheres. Concrete mixtures with ordinary Portland cement and two substitution rates of cement by microspheres—5% and 10%—are investigated. For all considered mixes, a constant water/binder ratio (w/b) equal to 0.50 was used. The distribution of the air voids and the compressive strength of the concrete were tested after 28 days. With the increasing mass of cement replacement by FAMs, the compressive strength decreases after 28 days. The total volume of the air voids in hardened concrete with fly ash microspheres tested by X-ray varies from 5.1% to 7.4%. The closed pores constitute more than 80% of the total content of air pores. The study proves that the use of microspheres grains with specific dimensions has a significant impact on concrete porosity. Their application in concrete technology can be an alternative aeration solution for fresh concrete mixes and an effective method for utilization.

UTILIZATION OF FLY ASH AND CONCRETE RESIDUE IN THE PRODUCTION OF GEOPOLYMER BRICKS

2017 ◽  
Vol 12 (1) ◽  
pp. 63-77 ◽  
Author(s):  
Siriporn Sirikingkaew ◽  
Nuta Supakata
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
Compressive Strength ◽  
Phase Composition ◽  
Fly Ash ◽  
Industrial Waste ◽  
X Ray Diffraction ◽  
X Ray ◽  
Scanning Electron

This study presents the development of geopolymer bricks synthetized from industrial waste, including fly ash mixed with concrete residue containing aluminosilicate compound. The above two ingredients are mixed according to five ratios: 100:0, 95:5, 90:10, 85:15, and 80:20. The mixture's physico-mechanical properties, in terms of water absorption and the compressive strength of the geopolymer bricks, are investigated according to the TIS 168-2546 standard. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses are used to investigate the microstructure and the elemental and phase composition of the brick specimens. The results indicate that the combination of fly ash and concrete residue represents a suitable approach to brick production, as required by the TIS 168–2546 standard.

Effect of Curing Time and Sintering to the Properties of Geopolymer Mortars

2017 ◽  
Vol 888 ◽  
pp. 184-187
Author(s):  
Salwa Ismail ◽  
Mohammad Faizal Mohd Razali ◽  
Izwan Johari ◽  
Zainal Arifin Ahmad ◽  
Shah Rizal Kasim
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Distilled Water ◽  
Curing Time ◽  
Pore Former ◽  
X Ray ◽  
Before And After ◽  
Naoh Solution ◽  
Added Water ◽  
Alkaline Activator

In this study, the geopolymer mortars were synthesized with fly ash (FA) and silica powder as aluminosilicate sources and a combination of sodium hydroxide (NaOH) solution, sodium silicate (Na2SiO3) solution and distilled water as alkaline activator. Commercial sago was used as a pore former in the mortars. The percentage of sago used were 10, 20 and 30 wt% of FA. The amount of added water used in each mixture was 5% by weight of FA, NaOH solution and Na2SiO3 solution. The formed geopolymer mortars were cured for 1, 3 and 7 days and sintered at 1000 °C. X-ray fluoresence (XRF) shown that FA contains higher amount of silica (SiO2) and alumina (Al2O3) which is important as aluminosilicate sources. The properties of the geopolymer mortars before and after sintered at 1000 °C have been investigated. The results show that geopolymer mortars with 10% of sago content with curing time of 7 days and sintered at 1000 °C give the highest compressive strength of 13.5 MPa.

Magnesium Phosphate Cement with Large Volume of Fly Ash

2012 ◽  
Vol 174-177 ◽  
pp. 802-805 ◽  
Author(s):  
Zhu Ding ◽  
Bi Qin Dong ◽  
Feng Xing
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Large Volume ◽  
Sodium Phosphate ◽  
Cement Mortar ◽  
Cementitious Materials ◽  
X Ray Diffraction ◽  
Monoammonium Phosphate ◽  
Ammonia Gas ◽  
X Ray

The accumulation of fly ash leads to severe problems in ecological environments. Various ways to excite the activity of fly ash in Portland cement based cementitious materials have been carried out for many years. In the present study, effect of large volume of fly ash in phosphate cement was studied. Dead burned magnesia, two phosphates (monoammonium phosphate and monosodium phosphate), and fly ash were used. The fabricated cement mortar specimens with different fly ash dosages were cured for 28 days in the lab air. Compressive strength was determined in 1d, 3d, 7d and 28d respectively. It is showed the compressive strength reduced with increase of fly ash content and increased with the curing time. After cured 28 days, the compressive strength of cement mortar developed to14MPa, when 80% fly ash was used. The reaction product, Na2HPO4•17H2O was found by X-ray diffraction analysis in sodium phosphate based cement. No ammonia gas was emitted and large volume of fly ash can be used in cement prepared from sodium phosphate. It is a new environmentally friendly cement material.

scholarly journals Parametric Strategy for Composite Cement Concrete Blended with Fly Ash & Glass Fiber

2020 ◽  
pp. 162-176
Author(s):  
Madhurima Das ◽  
Siba Prasad Mishra
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Glass Fiber ◽  
Building Materials ◽  
Cement Concrete ◽  
Strength Performance ◽  
X Ray ◽  
Natural Building ◽  
The Impact ◽  
Scanning Electron

Coping with population growth, houses are built to meet the hike. The prerequisites for concrete and steel reinforcements have surged up globally since last 3 to 4decades. Shortage of natural building materials, increased wastes from coal based industries to augment carbon foot print has worried the engineers to reuse their wastes (such as fibres, powders, granules, etc.) as building materials ingredient. Glass fibre has improved flexural capabilities with fly ash dosages in cement concrete and alternately helps in restricting environmental degradation. Present research aims at investigating the impact of glass fiber (at 1%, 2% and 3% addition) and fly ash (dosages of 10% and 20% over the existing fly ash in PPC). The ingredients and microstructure of composites are found by either X-ray fluorescent spectroscopy or scanning electron microscope. Experimental evaluation results of the blended composite concrete parameters of RCC are experimentally evaluated and compared have shown that concrete with 10% cement substitution with fly ash and 3% fibre showed optimum compressive strength performance than the concrete without fibre and fly ash and also chemically resistant against commonly used M-20 grade of Concrete.

scholarly journals The Filler Effect on Compressive Strength of Sulfur Concrete

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Wenwei Lin ◽  
Fan Fei ◽  
Qunjie Li
Keyword(s):  
Compressive Strength ◽  
Electron Microscope ◽  
Fly Ash ◽  
Scanning Electron Microscope ◽  
Chemical Reaction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Compressive Performance ◽  
Bonding Mode ◽  
Scanning Electron

The sulfur concrete samples were prepared by the optimized process, which were mixed with cement, fly ash and slag, respectively. The influence of the type and content of filler on the compressive strength of sulfur concrete was studied. The phase and micromorphology of filler and sulfur mixture were characterized by X-ray diffraction and scanning electron microscope, and the bonding mode was studied. The results show: the cement filler has the best effect on the compressive performance of sulfur concrete,and the compressive strength is 87.2 MPa by adding cement filler with the same quality as sulfur; there is no chemical reaction between filler and sulfur, and the filler is physically bonded to sulfur matrix.

scholarly journals STRENGTH DEVELOPMENT OF CONCRETE WITH FLY ASH ADDITION

2007 ◽  
Vol 13 (2) ◽  
pp. 115-122 ◽  
Author(s):  
Marta Kosior-Kazberuk ◽  
Małgorzata Lelusz
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Mathematical Models ◽  
Statistical Methods ◽  
Experimental Results ◽  
Strength Development ◽  
Hardened Concrete ◽  
Test Results ◽  
Different Types ◽  
Compressive Strength Of Concrete

Based on experimental results, mathematical models were elaborated to predict the development of compressive strength of concrete with fly ash replacement percentages up to 30 %. Strength of concrete with different types of cement (CEM I 42.5, CEM I 32.5, CEM III 32.5), after 2, 28, 90, 180 days of curing, have been analysed to evaluate the effect of addition content, the time of curing and the type of cement on the compressive strength changes. The adequacy of equations obtained was verified using statistical methods. The test results of selected properties of binders and hardened concrete with fly ash are also included. The analysis showed that concrete with fly ash is characterised by advantageous applicable qualities.

scholarly journals An Investigation of the Mechanical and Physical Characteristics of Cement Paste Incorporating Different Air Entraining Agents using X-ray Micro-Computed Tomography

Crystals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 23 ◽  
Author(s):  
Mohamed Abd Elrahman ◽  
Mohamed E. El Madawy ◽  
Sang-Yeop Chung ◽  
Stanisław Majer ◽  
Osama Youssf ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Compressive Strength ◽  
Thermal Insulation ◽  
Cement Paste ◽  
Aluminum Powder ◽  
Hollow Microspheres ◽  
Cement Composites ◽  
Micro Computed Tomography ◽  
Cement Pastes ◽  
X Ray

Improving the thermal insulation properties of cement-based materials is the key to reducing energy loss and consumption in buildings. Lightweight cement-based composites can be used efficiently for this purpose, as a structural material with load bearing ability or as a non-structural one for thermal insulation. In this research, lightweight cement pastes containing fly ash and cement were prepared and tested. In these mixes, three different techniques for producing air voids inside the cement paste were used through the incorporation of aluminum powder (AL), air entraining agent (AA), and hollow microspheres (AS). Several experiments were carried out in order to examine the structural and physical characteristics of the cement composites, including dry density, compressive strength, porosity and absorption. A Hot Disk device was used to evaluate the thermal conductivity of different cement composites. In addition, X-ray micro-computed tomography (micro-CT) was adopted to investigate the microstructure of the air-entrained cement pastes and the spatial distribution of the voids inside pastes without destroying the specimens. The experimental results obtained showed that AS specimens with admixture of hollow microspheres can improve the compressive strength of cement composites compared to other air entraining admixtures at the same density level. It was also confirmed that the incorporation of aluminum powder creates large voids, which have a negative effect on specimens’ strength and absorption.

Micromorphology and Mineralogy of Fly Ash and Lime Stabilized Bentonite

1987 ◽  
Vol 113 ◽  
Author(s):  
Ray E. Ferrell ◽  
Ara Arman ◽  
Gokhan Baykal
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Unconfined Compressive Strength ◽  
Calcium Silicate Hydrate ◽  
New Mineral ◽  
X Ray ◽  
Mineral Phases ◽  
Clay Aggregates ◽  
Montmorillonitic Clay

ABSTRACTCompacted fly ash, lime, bentonite and water mixtures were cured at 23° and 50°C, for 1, 28, 90 and 180 days. Cementitious products and microstructure were observed by scanning electron microscopy, energy dispersive x-ray spectrometry and x-ray diffractometry. Unconfined compressive strength changes are correlated to the formation of new mineral phases. For bentonite-limefly ash mixtures, strength increased from 1050 kPa (I day) to 2,300 kPa (90 days) and then slightly increased to 2,400 kPa after 180 days at ∼ 230C. Ettringite is the most abundant mineral associated with the increased compressive strength.New minerals identified in the 23°C mixtures include calcium silicate hydrate - Type 1, afwillite and ettringite. Acicular crystals of these and other minerals were formed by the hydration of lime and fly ash in the montmorillonitic clay. The cementitious phases create a rigid framework joining spheres and clay aggregates. Continued reaction dissolves some of the spheres and slightly reduces the rigidity of the cured samples.

Effect of CaO/SiO2 Ratio and TiO2 on Glass-Ceramics Made from Steel Slag and Fly Ash

2012 ◽  
Vol 217-219 ◽  
pp. 119-123 ◽  
Author(s):  
Bao Wei Li ◽  
Hua Chen ◽  
Ming Zhao ◽  
Xue Feng Zhang ◽  
Yong Sheng Du ◽  
...  
Keyword(s):  
Fly Ash ◽  
Bending Strength ◽  
Steel Slag ◽  
Glass Ceramics ◽  
Nucleating Agent ◽  
Spherical Particles ◽  
X Ray Diffraction ◽  
X Ray ◽  
Main Crystalline Phase ◽  
Average Size

Glass ceramics of the CaO-MgO-Al2O3-SiO2 system were fabricated by adopting the melting-casting procedure. Steel slag and fly ash were used as the major starting materials. The influence of CaO/SiO2 Ratio variations on the microstructure and mechanical properties were investigated using X-ray diffraction, scanning electron microscopy and property measurements. Augite is identified as the main crystalline phase of the as studied glass ceramics. The average size of augite grains in form of spherical particles is found within the range of 100-250nm. The bending strength of the glass-ceramics could reach as high as 170.74MPa. Increasing CaO/SiO2 show a beneficial influence on the crystallization of glass ceramics, and its effectiveness is inferior compared with that of increasing addition of nucleating agent, TiO2.

Influence of Addition of Fly Ash on Selected Properties of Concrete for Watertight Tunnel Lining

2015 ◽  
Vol 1100 ◽  
pp. 128-132
Author(s):  
Adam Hubáček ◽  
Tomáš Jarolím ◽  
Petra Macháňová
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Power Plant ◽  
High Water ◽  
Tunnel Lining ◽  
Partial Replacement ◽  
Hardened Concrete ◽  
Depth Of Penetration ◽  
The Czech Republic ◽  
Pressure Water

The paper deals with the topical theme of concrete for watertight tunnel lining, currently solved in the Czech Republic and abroad. The focus is on high water-tightness of concrete for production of these specific structures and other requirements from the point of durability of concrete for watertight tunnel lining. Experimental work followed previous research and was focused on testing of selected properties of concrete for watertight tunnel lining, either with only cement as a binder (reference mixtures) or with partial replacement of cement with fly ash from Detmarovice power plant. Manufactured specimens of fresh and hardened concrete were used for testing of development of compressive strength, depth of penetration with pressure water and development in hydration heat in time.

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