Fly Ash-Desulfurization Gypsum Mortar and Concrete Part II: Performances

2011 ◽  
Vol 243-249 ◽  
pp. 6880-6886 ◽  
Author(s):  
Yu Chen ◽  
Ying Li Gao
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Mass Loss ◽  
Drying Shrinkage ◽  
Strength Development ◽  
Composite Binder ◽  
Strength Concrete ◽  
Concrete Part ◽  
Standard Limit ◽  
Good Workability

FA-FGD mortar and concrete were manufactured and tested the main performances. With WFA-FGD taking 80~85% of the total composite binder by mass, mortar used in buildings was provided with good workability, enough mechanical properties specified for masonry in China, low drying shrinkage and strong sulfate corrosion, which was suitable for plastering or coating inside and outside walls. With LFA-FGD more than 30% in proportion, middle-strength concrete showed satisfactory workability with no segregation, no bleeding and low slump loss, stable strength development and low brittleness, about 60% of the domestic standard limit of wear mass loss in the specified test, good impermeability as well as excellent cracking resistance.

Fly Ash-Desulfurization Gypsum Mortar and Concrete Part I: Mix Proportions and Hydration

2011 ◽  
Vol 250-253 ◽  
pp. 809-816
Author(s):  
Yu Chen ◽  
Ying Li Gao
Keyword(s):  
Fly Ash ◽  
Flue Gas ◽  
Hydration Process ◽  
Cement Stone ◽  
Composite Binder ◽  
Strength Concrete ◽  
Concrete Hydration ◽  
Concrete Part ◽  
Flue Gas Desulphurization

Fly ash (FA) and flue gas desulphurization gypsum (FGD) were blended in proportion into a new composite binder added with cement, lime and some modifiers. In the paper, the mix proportions of composite binder with low-quality FA and FGD were studied. FA-FGD more than 80% with FA:FGD 3:2 was suggested for mortar, plastering and slurry while FA:FGD 2:1 and FA-FGD 30~40% was recommended for middle-strength concrete. Hydration process of typical mixtures of FA-FGD paste was investigated through SEM and XRD tests. The conclusion could be made that FA showed much improved pozzolana activity especially at early ages due to the existence of FGD as an ideal sulfate activator, which also crystallized later to strengthen the hardened paste. The microstructure of hydrated FA-FGD paste was more excellent than that of neat cement stone or one blended with the same percentage of pure FA.

scholarly journals Effects of the alkaline solution/binder ratio and curing condition on the mechanical properties of alkali-activated fly ash mortars

2017 ◽  
Vol 24 (5) ◽  
pp. 773-782
Author(s):  
Maochieh Chi
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Fly Ash ◽  
Alkaline Solution ◽  
Drying Shrinkage ◽  
Strength Development ◽  
Initial Surface ◽  
Binder Ratio ◽  
Curing Condition ◽  
Alkali Activated

AbstractThe study investigates the effects of the alkaline solution/binder ratio and the curing condition on the mechanical properties of alkali-activated fly ash (AAFA) mortars. Class F fly ash was used as the raw material, and sodium hydroxide and liquid sodium silicate were used for the preparation of alkaline activators. Three alkaline solution-to-binder ratios (0.35, 0.5, and 0.65) and four different initial curing conditions (curing in air at ambient temperature for 24 h, 30°C for 24 h, 65°C for 12 h, and 85°C for 6 h) were considered. Test results show that AAFA mortars with alkaline solution-to-binder ratio of 0.35 had higher compressive strength, lower drying shrinkage, lower water absorption, and lower initial surface absorption rate than the other mortars. Furthermore, the curing condition influenced the compressive strength development and drying shrinkage of AAFA mortars at early ages. AAFA mortars cured at 65°C for 12 h appeared to have superior mechanical properties. XRD demonstrates that the hydration products of AAFA mortars are mainly amorphous alkaline aluminosilicate gel, which attributed to the compressive strength. Consequently, the alkaline solution-to-binder ratio significantly affects more the mechanical properties than the curing condition based on the presented results.

Study on Strength Development of High Strength Concrete Containing Alccofine and Fly-Ash

2012 ◽  
Vol 2 (3) ◽  
pp. 102-104 ◽  
Author(s):  
Suthar Sunil B ◽  
◽  
Dr. (Smt.) B. K. Shah Dr. (Smt.) B. K. Shah
Keyword(s):  
Fly Ash ◽  
High Strength Concrete ◽  
High Strength ◽  
Strength Development ◽  
Strength Concrete

scholarly journals Long-Term Physical and Mechanical Properties and Microstructures of Fly-Ash-Based Geopolymer Composite Incorporating Carbide Slag

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6692
Author(s):  
Xianhui Zhao ◽  
Haoyu Wang ◽  
Linlin Jiang ◽  
Lingchao Meng ◽  
Boyu Zhou ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Room Temperature ◽  
Physical And Mechanical Properties ◽  
Drying Shrinkage ◽  
Fine Aggregate ◽  
Property Development ◽  
Industrial Solid Waste ◽  
Carbide Slag

The long-term property development of fly ash (FA)-based geopolymer (FA−GEO) incorporating industrial solid waste carbide slag (CS) for up to 360 d is still unclear. The objective of this study was to investigate the fresh, physical, and mechanical properties and microstructures of FA−GEO composites with CS and to evaluate the effects of CS when the composites were cured for 360 d. FA−GEO composites with CS were manufactured using FA (as an aluminosilicate precursor), CS (as a calcium additive), NaOH solution (as an alkali activator), and standard sand (as a fine aggregate). The fresh property and long-term physical properties were measured, including fluidity, bulk density, porosity, and drying shrinkage. The flexural and compressive strengths at 60 d and 360 d were tested. Furthermore, the microstructures and gel products were characterized by scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS). The results show that the additional 20.0% CS reduces the fluidity and increases the conductivity of FA−GEO composites. Bulk densities were decreased, porosities were increased, and drying shrinkages were decreased as the CS content was increased from 0.0% to 20.0% at 360 d. Room temperature is a better curing condition to obtain a higher long-term mechanical strength. The addition of 20.0% CS is more beneficial to the improvement of long-term flexural strength and toughness at room temperature. The gel products in CS−FA−GEO with 20.0% CS are mainly determined as the mixtures of sodium aluminosilicate (N−A−S−H) gel and calcium silicate hydration (C−S−H) gel, besides the surficial pan-alkali. The research results provide an experimental basis for the reuse of CS in various scenarios.

scholarly journals Characterizing the Performance of Ternary Concrete Mixtures Involving Slag and Metakaolin

2020 ◽  
Vol 5 (2) ◽  
pp. 14
Author(s):  
Matthew S. Sullivan ◽  
Mi G. Chorzepa ◽  
Stephan A. Durham
Keyword(s):  
Mechanical Properties ◽  
Thermal Expansion ◽  
Fly Ash ◽  
Coefficient Of Thermal Expansion ◽  
Drying Shrinkage ◽  
Chloride Ion ◽  
Cementitious Materials ◽  
Ternary Mixtures ◽  
Modulus Of Rupture ◽  
Ternary Blends

Ternary blends of cementitious materials are investigated. A cement replacement level of 45% is used for all ternary mixtures consisting of 15% metakaolin and 30% slag replacements. Three metakaolin and two blast furnace slag, referred to as ‘slag’ for short, products commercially available are used to compare performance in ternary blends. A mixture with a 45% fly ash replacement is included to serve as a benchmark for performance. The control mixture contains 422 kg of cement per cubic meter of concrete, and a water-to-cementitious material ratio of 0.43 is used for all mixtures with varying dosages of superplasticizer to retain workability. Mixtures are tested for mechanical properties, durability, and volumetric stability. Mechanical properties include compression, split-cylinder tension, modulus of rupture, and dynamic Young’s modulus. Durability measures are comprised of rapid chloride-ion penetrability, sulfate resistance, and alkali–silica reactivity. Finally, the measure of dimensional stability is assessed by conducting drying shrinkage and coefficient of thermal expansion tests. Results indicate that ternary mixtures including metakaolin perform similarly to the control with respect to mechanical strength. It is concluded that ternary blends perform significantly better than both control and fly ash benchmark in tests measuring durability. Furthermore, shrinkage is reduced while the coefficients of thermal expansion are slightly higher than control and the benchmark.

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.

Comparative Investigations of some Properties Related to Durability of Cement Concretes Containing Different Fly Ashes

2014 ◽  
Vol 1054 ◽  
pp. 154-161 ◽  
Author(s):  
Wojciech Kubissa ◽  
Barbara Pacewska ◽  
Iwona Wilińska
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Fly Ash ◽  
Silica Fume ◽  
Low Permeability ◽  
Concrete Durability ◽  
Cement Concrete ◽  
Fly Ashes ◽  
Chloride Migration ◽  
Good Workability

The results of research of mechanical properties and selected other characteristics influencing durability of cement concretes containing cement substitutes were presented. Cement concretes performed with conventional fly ash, fluidised fly ash and their mixture were investigated. The obtained results were compared with findings registered for two types of concrete performed without cement replacements and with cement concrete containing silica fume. The results have shown that cement concrete with predetermined 28-day compressive strength of about 50 MPa and good workability may be obtained using different cement replacements. Generally, these cement concretes exhibited also favorable properties related to concrete durability, i.e. low permeability and sorptivity, and significant reduction of chloride migration coefficient. Favourable results were obtained for cement concrete containing mix of conventional and fluidised fly ashes: good workability, compressive strength after 28th day exceeding 50 MPa, low permeability of water, and low sorptivity, as well as low coefficient of chloride migration. These features were similar as for cement concrete containing silica fume.

Experiment and Micro-Mechanism Study on Mechanical Properties and Durability of High-Calcium Fly Ash Concrete

2011 ◽  
Vol 480-481 ◽  
pp. 59-65
Author(s):  
Shuang Xi Li ◽  
Tuan She Yang ◽  
Zhi Ming Wang ◽  
Quan Hu
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Frost Resistance ◽  
Strength Development ◽  
Hydration Reaction ◽  
Optimal Dosage ◽  
Fly Ash Concrete ◽  
Low Calcium ◽  
High Calcium ◽  
High Calcium Fly Ash

Low-calcium fly ash is paid much attention for its wide use in engineering, the research and application technology of it are very mature, but as to high-calcium fly ash concrete, the researches on stability, mechanical property and durability of it are very less , The existing researches are still inadequate for practice of engineering. As to this problem, using small shek kip hydropower project as example, the volume stability of high-calcium fly ash concretes with different fly ash dosages are tested, then the optimal dosage of the high-calcium fly ash is determined; based on this, the impacts of high-calcium fly ash on the performance of mechanical properties , impermeability and frost resistance of concrete are studied; Finally, macro performance is analyzed from a micro-mechanism point of view through taking the electron micrograph. As the study shows, the optimal dosage of high-calcium fly ash should be taken as 20% -25%; for the concrete with special requirements, the dosage can be relaxed to 30% when the high-calcium fly ash achieves high quality. The compressive strength of high-calcium fly ash concrete is higher than the low-calcium fly ash concrete. Strength development advantage of high-calcium fly ash concrete reflects at the early age, this advantage takes the trend of weakening as the development of age. Concrete mixed with high-calcium fly ash has good performance in impermeability. The high-calcium fly ash has high activity, the high-calcium fly ash and secondary hydration reaction products can be filled into the pore capillary and cracks of the concrete structure, improving the pore structure, thereby increasing the density of cement paste. High-calcium fly ash concrete has good performance in frost resistance. The destructive effects of freeze-thaw cycles on cement structure has connection with the microstructure of cement and impermeability , the improvement of impermeability avoids the water entering into the concrete, reduces the risk of destruction caused by frost heave.The study on micro-mechanism proves well the macro-phenomena above.

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