Comparison of innovative nano fly ash with conventional fly ash and nano-silica

2014 ◽  
Vol 41 (5) ◽  
pp. 396-402 ◽  
Author(s):  
Seong-Soo Kim ◽  
R. Doug Hooton ◽  
Tae-Jun Cho ◽  
Jeong-Bae Lee
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Physical Method ◽  
Pozzolanic Reaction ◽  
Superior Performance ◽  
Particle Sizes ◽  
Nano Silica ◽  
Initial Strength ◽  
Carbonation Resistance ◽  
Chloride Penetration Resistance

This report is an experimental study on the nano-powdering of fly ash and the improvement of cement performance by nano fly ash. Mortars with nano fly ash or nano-silica produced by a physical method are compared with mortar without a nano-binder. Mortar with nano-silica showed rapid setting. However, mortar with fly ash or nano fly ash exhibited delayed setting. The smaller the particle sizes, the higher is the compressive strength, demonstrating that mortar with nano fly ash shows superior performance with higher compressive strength from the beginning. Durability assessments revealed that chloride penetration resistance increased by 70% for mortar with nano fly ash or nano-silica. This shows that mortar with a smaller particle binder has excellent carbonation resistance. Nano-powdering effectively enhances the activation of a pozzolanic reaction and provides densely charged effects. These changes solve the problem of initial strength reduction — the greatest weakness of fly ash.

scholarly journals Effect of Morphologically Controlled Hematite Nanoparticles on the Properties of Fly Ash Blended Cement

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 1003
Author(s):  
Pantharee Kongsat ◽  
Sakprayut Sinthupinyo ◽  
Edgar A. O’Rear ◽  
Thirawudh Pongprayoon
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Size Distribution ◽  
Cement Hydration ◽  
Blended Cement ◽  
Spherical Shape ◽  
Particle Sizes ◽  
Fe2o3 Nanoparticles ◽  
Structure And Properties ◽  
Hematite Nanoparticles

Several types of hematite nanoparticles (α-Fe2O3) have been investigated for their effects on the structure and properties of fly ash (FA) blended cement. All synthesized nanoparticles were found to be of spherical shape, but of different particle sizes ranging from 10 to 195 nm depending on the surfactant used in their preparation. The cement hydration with time showed 1.0% α-Fe2O3 nanoparticles are effective accelerators for FA blended cement. Moreover, adding α-Fe2O3 nanoparticles in FA blended cement enhanced the compressive strength and workability of cement. Nanoparticle size and size distribution were important for optimal filling of various size of pores within the cement structure.

High Volume Slag and Slag-Fly Ash Blended Cement Pastes Containing Nano Silica

2019 ◽  
Vol 967 ◽  
pp. 205-213
Author(s):  
Faiz U.A. Shaikh ◽  
Anwar Hosan
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Cement Paste ◽  
Ordinary Portland Cement ◽  
Blended Cement ◽  
High Volume ◽  
Ash Content ◽  
Partial Replacement ◽  
Nano Silica ◽  
Cement Pastes

This paper presents the effect of nanosilica (NS) on compressive strength and microstructure of cement paste containing high volume slag and high volume slag-fly ash blend as partial replacement of ordinary Portland cement (OPC). Results show that high volume slag (HVS) cement paste containing 60% slag exhibited about 4% higher compressive strength than control cement paste, while the HVS cement paste containing 70% slag maintained the similar compressive strength to control cement paste. However, about 9% and 37% reduction in compressive strength in HVS cement pastes is observed due to use of 80% and 90% slag, respectively. The high volume slag-fly ash (HVSFA) cement pastes containing total slag and fly ash content of 60% exhibited about 5%-16% higher compressive strength than control cement paste. However, significant reduction in compressive strength is observed in higher slag-fly ash blends with increasing in fly ash contents. Results also show that the addition of 1-4% NS improves the compressive strength of HVS cement paste containing 70% slag by about 9-24%. However, at higher slag contents of 80% and 90% this improvement is even higher e.g. 11-29% and 17-41%, respectively. The NS addition also improves the compressive strength by about 1-59% and 5-21% in high volume slag-fly ash cement pastes containing 21% fly ash+49%slag and 24% fly ash+56%slag, respectively. The thermogravimetric analysis (TGA) results confirm the reduction of calcium hydroxide (CH) in HVS/HVSFA pastes containing NS indicating the formation of additional calcium silicate hydrate (CSH) gels in the system. By combining slag, fly ash and NS in high volumes e.g. 70-80%, the carbon footprint of cement paste is reduced by 66-76% while maintains the similar compressive strength of control cement paste. Keywords: high volume slag, nanosilica, compressive strength, TGA, high volume slag-fly ash blend, CO2 emission.

scholarly journals Thermal, Physico-Chemical, and Mechanical Behaviour of Mass Concrete with Hybrid Blends of Bentonite and Fly Ash

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 60 ◽  
Author(s):  
Muhammad Ahad ◽  
Muhammad Ashraf ◽  
Rabinder Kumar ◽  
Mukhtar Ullah
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Thermal Stresses ◽  
Thermo Gravimetric Analysis ◽  
Xrd Analysis ◽  
Pozzolanic Reaction ◽  
Pulse Velocity ◽  
Mass Concrete ◽  
Gravimetric Analysis ◽  
Physico Chemical

Mass concrete has been commonly known for its thermal stresses which arise due to the entrapment of hydration temperature susceptible to thermal cracking. The utilization of mineral additives is a promising and widely adopted technique to mitigate such effects. This paper presents the thermal, physico-chemical, mechanical, and morphological behaviour of mass concrete with blends of bentonite (BT) and fly ash (FA). Apart from the rise in temperature due to hydration, the compressive strength, ultrasonic pulse velocity (UPV), differential thermal analysis (DTA), thermo-gravimetric analysis (TGA), X-ray diffraction (XRD) analysis, and microstructure were studied. The results of this study revealed that the substitution of BT and FA significantly improved the compressive strength and development rate of UPV in the mass concrete samples. The FA concrete (FC) specimen presented the lowest temperature during the peak hours compared to all other concrete mixes studied in this research. Bentonite concrete (BC) was also found to be more effective in controlling the escalation of temperature in mass concrete. Scan electron microscopy (SEM) micrographs presented partially reacted FA particles in a mix. XRD and DTA analysis indicated that the concentration of calcium hydroxide (CH) declined by substituting FA and BT, specifically in ternary blends, which was due to the dilution effect and consumption of CH through the pozzolanic reaction.

scholarly journals Feasibility of Pulverized Oyster Shell as a Cementing Material

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Chou-Fu Liang ◽  
Hung-Yu Wang
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Oyster Shell ◽  
Pozzolanic Reaction ◽  
Compaction Process ◽  
Lower Strength ◽  
Compacted Soil ◽  
Cementing Material ◽  
Unconfined Strength ◽  
Strength Variance

This research intends to study the cementing potential of pulverized oyster shell, rich in calcium, when mixed with fly ash and soil. Cylindrical compacted soil and cubic lime specimens with different proportions of the shells and fly ash are made to study the strength variance. Soil, which is classified as CL in the USCS system, commercialized pulverized oyster shell, F-type fly ash, and lime are mixed in different weight percentages. Five sample groups are made to study the compressive strength of soil and lime specimens, respectively. The lime cubes are made with 0.45 W/B ratio and the cylindrical soils are compacted under the standard Procter compaction process with 20% moisture content. The results show that increment of shell quantity result to lower strength on both the soil and lime specimens. In a 56-day curing, the compressive strength of the lime cubes containing fly ash increases evidently while those carrying the shell get little progress in strength. The soil specimens containing fly ash gradually gain strength as curing proceeds. It suggests that mixtures of the shell and fly ash do not process any Pozzolanic reaction nor help to raise the unconfined strength of the compacted soil through the curing.

Preparation and Properties of Lightweight, High-Strength Insulation Materials Using Fly Ash Floating Beads

2016 ◽  
Vol 697 ◽  
pp. 599-603
Author(s):  
Ya Peng Dai ◽  
Xing Yong Gu ◽  
Wei Xia Dong ◽  
Ting Luo
Keyword(s):  
Compressive Strength ◽  
Heat Conduction ◽  
Fly Ash ◽  
High Strength ◽  
Volume Density ◽  
Particle Sizes ◽  
Heat Conduction Coefficient ◽  
Insulation Materials ◽  
Test Instrument ◽  
Save Energy

In our paper, to save energy conservation and environmental protection, and in view of waste fly ash floating bead with excellent properties such as light and refractory, lightweight insulation materials was prepared using fly ash floating beads as the main materials. Firstly, two different fly ash floating bead contents on the properties of the light and refractory material were investigated. Then, on the basis of the optimum fly ash floating bead content, effects of various different particle sizes and firing temperature on the bulk density, compressive strength and the heat conduction coefficients of the samples were studied. The microstructure of the light-weight refractory materials was characterized by XRD and SEM. The heat conduction coefficient (λ') of the samples were also measured by the self-made test instrument. The experimental results showed that the properties of the as-prepared sample using 80% fly ash floating beads was superior to that of 95 % fly ash floating beads. The optimal volume density of 0.60-1.04 g/cm3, compressive strength of 10.6-39.5 MPa and the heat conduction coefficient of 0.183-0.25 °C·g/ min·cm2 were achieved in the presence of 80% fly ash floating beads with 120-160 particle size at 1200°C-1300°C, which has the potential application in lightweight insulation materials.

Influence of Fly Ash and Basalt Fibers on Strength and Chloride Penetration Resistance of Self-Consolidating Concrete

2016 ◽  
Vol 866 ◽  
pp. 3-8 ◽  
Author(s):  
Osama Ahmed Mohamed ◽  
Waddah Al Hawat
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Portland Cement ◽  
Strength Properties ◽  
Chloride Penetration ◽  
Partial Replacement ◽  
Basalt Fibers ◽  
Self Consolidating Concrete ◽  
Chloride Penetration Resistance ◽  
Hardened Properties

Fly ash is a sustainable partial replacement of Portland cement that offers significant advantages in terms of fresh and hardened properties of concrete. This paper presents the findings of a study that aims at assessing the durability and strength properties of sustainable self-consolidating concrete (SCC) mixes in which Portland cement was partially replaced with 10%, 20%, 30%, and 40% fly ash. The study confirms that replacing Portland cement with fly ash at all of the percentages studied improves resistance of concrete to chloride penetration. The 40% fly ash mix exhibited the highest resistance to chloride penetration compared to the control mix. Despite the relative drop in compressive strength after 7 days of curing, the 28-day compressive strength of 40% SCC mix reached 55.75 MP, which is very close to the control mix. The study also confirms that adding 1%, 1.5%, and 2% basalt fibers, respectively, to the 40% fly ash mix improves the resistance to chloride penetration compared to the mix without basalt fibers.

Effects of Fly Ash Particle Sizes on the Compressive Strength and Fracture Toughness of High Performance Concrete

2011 ◽  
Vol 284-286 ◽  
pp. 984-988
Author(s):  
An Shun Cheng ◽  
Yue Lin Huang ◽  
Chung Ho Huang ◽  
Tsong Yen
Keyword(s):  
Fracture Toughness ◽  
Particle Size ◽  
Compressive Strength ◽  
Fly Ash ◽  
High Performance ◽  
High Performance Concrete ◽  
Concrete Strength ◽  
Bending Test ◽  
Strength Development ◽  
Particle Sizes

The study aims to research the effect of the particle size of fly ash on the compressive strength and fracture toughness of high performance concrete (HPC). In all HPC mixtures, the water-to-binder ratio selected is 0.35; the cement replacement ratios includes 0%, 10% and 20%; the particle sizes of fly ash have three types of passing through sieves No. 175, No. 250 and No. 325. Three-point-bending test was adopted to measure the load-deflection relations and the maximum loads to determine the fracture energy (GF) and the critical stress intensity factor (KSIC). Test results show that adding fly ash in HPC apparently enhances the late age strengths of HPC either for replacement ratio of 10% or 20%, in which the concrete with 10% fly ash shows the higher effect. In addition, the smaller the particle size is the better the late age concrete strength will be. The HPC with the finer fly ash can have higher strength development and the values of GF and KSIC due to the facts of better filling effect and pozzolanic reaction. At late age, the GF and KSIC values of concrete with 10% fly ash are all higher than those with 20% fly ash.

Sign in / Sign up

Export Citation Format

Share Document