Effect of Fly Ash on Mechanical Properties and Structure of CaO-Al2O3-P2O5-SiO2 System

2011 ◽  
Vol 55-57 ◽  
pp. 1233-1236
Author(s):  
Xiu Shu Tian ◽  
Shi Gang Mei ◽  
Shu Xia Ren
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Experimental Results ◽  
Early Age ◽  
Hydration Products ◽  
Different Ages ◽  
Early Strength ◽  
Gel System

In this paper, mainly CaO-Al2O3-P2O5-SiO2gel system and the effect of fly ash on the mechanical properties and the microstructure of the hydrated system without and within lay ash at different ages have been studied. The structures were characterized by XRD and SEM. The experimental results show that fly ash does not hydrate at the early age and provides the interface, so the hydration products of CaO-Al2O3-P2O5-SiO2system is deposited directly on its surface, which lead to a lower early strength; but fly ash hydrates at the later age and improves the hydration of CaO-Al2O3-P2O5-SiO2system.

scholarly journals The Optimization of Calcareous Fly Ash-Added Cement Containing Grinding Aids and Strength-Improving Additives

2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Gökhan Kaplan ◽  
Sadık Alper Yildizel ◽  
Selçuk Memiş ◽  
Ali Uğur Öztürk
Keyword(s):  
Fly Ash ◽  
Ash Content ◽  
Early Age ◽  
Economic Factors ◽  
Hydration Products ◽  
Chemical Additive ◽  
Cement Production ◽  
Grinding Aids ◽  
Cement Mortars ◽  
Early Strength

This is an experimental study which explores the physical, mechanical, and economic factors involved in the production of type CEM II A-B/W cement. In this context, 4 cement additives were used in two different dosages (200 and 800 g/t). Class C fly ash was used for composite cement production at ratios of 5%, 20%, and 35%. It was shown that Blaine fineness increases with the increasing fly ash content. The use of fly ash at ratios of 5% and 20% was not found to have any unfavorable effects on the compressive strength at the early days. It is found that the use of additive for improving the early-age strength is preferable when fly ash is used. It is possible to produce Class 52.5 N cement using additives to improve early strength and 20% fly ash. Loss in strength was observed in cement mortars produced using glycol-based grinding aid. Increasing the dosage of chemical additive also led to loss in strength due to nonhomogeneous distribution of hydration products. As a result, grinding fly ash with clinker and the use of cement chemicals contribute to the cement sector in terms of sustainability. It is possible to produce cements with improved mechanical properties especially with the use of 20% fly ash.

Study on the Properties of Sea Sand Concrete with Fly Ash

2014 ◽  
Vol 1065-1069 ◽  
pp. 1854-1857 ◽  
Author(s):  
Yi Jiang ◽  
Jun Zhe Liu ◽  
Wu Sun ◽  
Chao Yi Zheng ◽  
Si Yun Wu
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Chloride Ion ◽  
Main Issue ◽  
Microscopic Structure ◽  
Hydration Products ◽  
Ion Content ◽  
Sea Sand ◽  
Early Strength ◽  
Chlorine Ion

The harmful chloride ion in sea sand concrete is the main issue that hinders its application, proposing a method using fly ash the active mineral, chloride ion content of harmful curing of sea sand concrete, to improve the durability of sea sand concrete. The experiment studies the influence of sand in the chlorine ion and fly ash on the strength of concrete, and analyzes microscopic structure and hydration products of concrete. Research results show that: the sea sand concrete with 20% fly ash prepared has good mechanical properties and durability; the existence of Cl- on the early strength of sea sand concrete has a positive promoting role, but has negative effective on the later development.

Research on Mechanical Properties of C100 High-Strength Concrete Used for Frozen Shaft

2012 ◽  
Vol 598 ◽  
pp. 388-392
Author(s):  
Hong Qiang Chu ◽  
Lin Hua Jiang ◽  
Ning Xu ◽  
Chuan Sheng Xiong
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Fly Ash ◽  
High Strength Concrete ◽  
High Strength ◽  
Cementitious Materials ◽  
Poisson's Ratio ◽  
Strength Concrete ◽  
Tensile Elastic Modulus ◽  
Early Strength

The mechanical properties of C100 high-strength concrete used for frozen shaft were studied in this research. The results demonstrate that: The cementitious materials 570kg/m3 concrete 28 strength is only 104.5MPa, which is lower than the C100 requirements; the early strength (3d) of the concrete doped with 30% admixture is less than 20% admixture concrete, but with the age increase, its strength gradually reaches close to concrete doped with 20% admixture, and eventually exceeds the concrete doped with 20% admixture.The tension-compression of high strength concrete doped with 15% fly ash and 15% slag is the smallest, while the tension-compression of the concrete doped 10% fly ash and 10% slag reaches the maximum.The Poisson's ratio of C100 concrete is between 0.20 and 0.24; the compressive elastic modulus is about 50GPa; and the tensile elastic modulus is about 110GPa.

Effect of Fly Ash and Activator on Performance of Steam-Cured Concrete

2010 ◽  
Vol 113-116 ◽  
pp. 1013-1016 ◽  
Author(s):  
Zhi Min He ◽  
You Jun Xie ◽  
Guang Cheng Long ◽  
Jun Zhe Liu
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Fly Ash ◽  
Precast Concrete ◽  
Early Age ◽  
Flexure Strength ◽  
Concrete Elements ◽  
Chemical Activator

In precast concrete elements manufacturing, steam-cured concrete incorporating 30% fly ash encountered the problem of a too low demoulding compressive strength. To resolve it, this paper developed a new steam-cured concrete (AFSC) incorporating fly ash and a chemical activator. Experiments were conducted to investigate the mechanical properties of AFSC. The corresponding mechanism was also discussed by testing the microstructure of concrete. Results indicate that the demoulding compressive strength of AFSC can meet production requirements, and compressive and flexure strength of AFSC at later ages increase well. Compared with that of ordinary steam-cured concrete, AFSC has a higher tensile strength, and the capability of AFSC to resist cracks is enhanced remarkably. At an early age, addition of the chemical activator can distinctly accelerate the extent of hydration of the fly ash cement systems, and thus the microstructure of concrete becomes denser.

Effect of fine fly ash and calcium hydroxide on air void structure in very-early-strength latex-modified concrete

2015 ◽  
Vol 42 (10) ◽  
pp. 797-807
Author(s):  
Pangil Choi ◽  
Sung Il Jeon ◽  
Kyong-Ku Yun
Keyword(s):  
Fly Ash ◽  
Calcium Hydroxide ◽  
Bridge Decks ◽  
Time Frame ◽  
Early Age ◽  
Freeze Thaw ◽  
Void Structure ◽  
Early Strength ◽  
Air Void ◽  
Air Void Structure

Very-early-strength latex-modified concrete (VES-LMC) was developed for rapid repairs of distresses in concrete bridge decks and pavements, with the emphasis on early-age strength gain so that the repaired bridges and pavements can be opened to traffic within the time frame required in the specifications. However, there are two main concerns in the use of VES-LMC — early-age cracking and poor air void structure. The main objective of this study was to further improve VES-LMC to minimize early-age cracking and improve freeze–thaw durability, which included the use of fine fly ash (FFA) and calcium hydroxide (CH). Laboratory experiments were conducted on VES-LMC materials with cement replaced with FFA as well as CH, and various tests performed. Early-age drying shrinkages of VES-LMC containing both FFA and CH in the amounts evaluated in this study were smaller than that of VES-LMC with no replacements. It is expected that the use of FFA and CH in the range evaluated in this study will reduce the cracking potential of VES-LMC. Overall, the replacement of cement with FFA and CH improved the characteristics of entrained air void system, which will enhance the durability of VES-LMC against freeze–thaw damage. Scanning electron microscope and energy dispersive spectroscopy analysis indicate the primary mechanism of the generation of small sized air voids in concretes containing adequate amount of FFA and CH is the gas formation reaction between citric acid solutions and CH during concrete mixing. It is expected that the inclusion of adequate amounts of FFA and CH in VES-LMC will improve the performance of repaired bridge decks and pavements in terms of reduced cracking and improved freeze-thaw durability.

FLEXURAL BEHAVIOR OF HIGH STRENGTH GEO-POLYMER CONCRETE BEAMS

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Vankudothu Bhikshma ◽  
Kandiraju Promodkumar ◽  
Putta Panduranghiah
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Research Work ◽  
High Strength ◽  
Experimental Results ◽  
Flexural Behavior ◽  
Polymer Concrete ◽  
Conventional Concrete ◽  
Granulated Blast Furnace Slag ◽  
Load Carrying

The demand for concrete is increasing day by day. As the consumption of cement is increased, environmental issues arise due to the release of CO2 during the manufacturing of cement. The objective of this research work is to produce a pollution free concrete with a combination of fly ash and GGBS (Ground granulated blast furnace slag) and without the use of cement. In this paper an attempt was made to study the mechanical properties of high strength geo-polymer concrete of grade M60 using GGBS, fly ash and micro silica. The testing program was planned for the mechanical properties of geo-polymer concrete and flexural behavior of corresponding beams. The experimental results indicated that the geo-polymer concrete M60 grade has a compressive strength of 70.45 MPa at the age of 28 days cured at ambient condition. Further, flexural strength and split tensile strengths for M60 grade high strength geo-polymer concrete at 28 days were observed to be 5.45 MPa and 3.63 MPa respectively. The modulus of elasticity was higher than the theoretical value proposed by IS 456-2000. It was also observed that the load carrying capacity of M60 grade high strength geo-polymer concrete found to be more than corresponding grade conventional concrete. The load-deflection, moment-curvature relationships were studied. The experimental results were encouraging to continue for further research in the area high strength geo-polymer concrete.

A Study on the Development Mechanism of Early Strength in Cement Mortar Using an Early-Strength Polycarboxylated Agent

2007 ◽  
Vol 348-349 ◽  
pp. 473-476
Author(s):  
Won Jun Park ◽  
Han Seung Lee ◽  
Ki Bong Park
Keyword(s):  
Compressive Strength ◽  
High Performance ◽  
Cement Mortar ◽  
Early Age ◽  
Hydration Products ◽  
Degree Of Hydration ◽  
Exact Analysis ◽  
Mortar Strength ◽  
Early Strength ◽  
Micro Structures

It is well known that PC (polycarboxylate) agent is superior to other agents for the early-strength of concrete. Thus, this study investigates the development of mortar strength using various agents. To prove this, various factors were tested. Furthermore, this study measured compressive strength at the age of 18, 24, 36, 72, and 168 hours and gave a request text TG/DTA to observe minute structures. In addition, this study took pictures of minute structures using an SEM for each agent at the same age. According to the results, mortar using an early-strength PC agents is faster than a general water reducing AE agent, high performance PC agents, and other agents in the acceleration of hydration at the same early age. A TG/DTA test shows that the early-strength PC agents create more hydration products, such as Ca(OH)2, than others at the same age. The degree of pH in each agent is unrelated to the degree of hydration in mortar. An MIP analysis confirms these results. However, other methods are required the exact analysis of micro structures.

Research on the Basic Mechanical Properties of Fly Ash Fiber Reinforced Concrete

2011 ◽  
Vol 261-263 ◽  
pp. 8-12
Author(s):  
Shu Shan Li ◽  
Ming Xiao Jia ◽  
Dan Ying Gao
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Fly Ash ◽  
Compressive Modulus ◽  
Fiber Reinforced Concrete ◽  
Cement Ratio ◽  
Influence Mechanism ◽  
Fiber Concrete ◽  
Early Strength

The basic mechanical properties of fly ash fiber concrete were tested. The influences to the compressive strength, splitting tensile strength and compressive modulus of elasticity of fiber concrete by water-cement ratio, dosage of fly ash and other factors were analyzed. The influence mechanism of fly ash to concrete is discussed. The results indicate that with the increase of the dosage of fly ash, the early strength of double-doped concrete is reduced, while the later strength of concrete was obviously increased.

Research on Preparation and Properties of New Type Desulfurization Gypsum Block

2014 ◽  
Vol 540 ◽  
pp. 217-220
Author(s):  
Chuan Wei Du ◽  
Ying Lv ◽  
Guo Zhong Li
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Water Resistance ◽  
Experimental Results ◽  
New Type ◽  
Cementing Material ◽  
The Impact

Desulfurization building gypsum was used as the main gelled material and fly ash was used as filler to prepare the new type desulfurization gypsum block. the mechanical properties of the new type desulfurization gypsum block was improved by adding compound excitation agent into the desulphurization gypsum-fly ash cementing material to stimulate its activity. The water resistant performance of the new type desulfurization gypsum block was improved through adding wax-alcohol compound waterproofing agent into it. Experimental results show that when the filling amount of fly ash was 20%(the quality of desulfurization gypsum), the impact on the strength of gypsum was minimal; when the dosage of compound excitation agent was 1.75%, the excitation effect of desulphurization gypsum-fly ash cementing material was best; when the dosage of wax-alcohol compound waterproofing agent was 0.4%, the water resistance of new desulfurization gypsum block was optimal.

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