1 edition of Fly ash increases resistance of concrete to sulfate attack found in the catalog.
Fly ash increases resistance of concrete to sulfate attack
|Contributions||Dikeou, J. T.|
|The Physical Object|
|Number of Pages||17|
Increased strength, resistance to weathering, bond with reinforcement, and watertightness Fly ash and ground granulated blast furnace slag will generally retard the setting time. This is: To minimize damage from sulfate attack in a concrete slab, it is most important to _____. 10 Pounds. The resistance of fly ash concrete to sulfate attack is dependent on both its chemical and physical characteristics. The chemistry and mineralogy of both fly ash and cement influence the sulfate resistance of hydration products, while the permeability of concrete influences the rate of ingress of sulfate by: 3.
These observations indicate that the RC had a worse resistance to sulfate attack than NC. However, when the cement paste was replaced with geopolymer, the recycled concrete could be modified by GGBS and fly ash-based geopolymer, resulting in a better resistance to sulfate attack than by: Boral Resources offers a wide variety of pozzolans to improve concrete performance during placement and throughout the life of the project. Boral is a major source of the most commonly used pozzolan, Fly Ash, produced from the combustion of coal in power generating plants.
Fly ash based GPC specimens suffered strength loss due to sodium and magnesium sulfates, whereas an increase in strength was observed in the presence of calcium sulfates. In comparison to the GPC s, OPC Type V cement exhibited super ior resistance to all the three sulfates (CaSO 4, MgSO 4, and NaSO 4). M icrostructural, che mical and pore. The resistance of seven different concrete mixtures against a % sulfuric acid solution was examined. The difference between high sulfate resistant Portland cement and blast furnace cement, as well as the influence of polymer modifications of the concrete and the addition of silica fume were issues of the investigation. All concrete mixtures were submitted to an alternating immersion and Cited by:
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Get this from a library. Fly ash increases resistance of concrete to sulfate attack. [James T Dikeou]. Additional Physical Format: Online version: Dikeou, James T. Fly ash increases resistance of concrete to sulfate attack. Washington, D.C.: United States Department of.
Fly Ash Increases Resistance to Sulphate Attack August 95 strong water reducer and aids in reducing water/ cementitious ratio. Lowering water/cementitious ratio significantly can lead to more sulphate resisting concrete. To ensure the most durable concrete possible, fly ash is an essential ingredient when the project will beFile Size: 20KB.
Class F Fly Ash INCREASES RESISTANCE TO SULFATE ATTACK Sulfate Attack Is A Two-Phased Process Sulfates combine with calcium hydroxide generated during cement hydration to form calcium sulfate (gypsum).
The volume of this gypsum is greater than the sum of its components causing internal pressure and expansion, which fractures the Size: KB.
the resistance of sulfate attack, and the sulfate resistance is increased with the increase of amount of fly ash. The reason may be connected with the pozzonlanic reaction of fly ash. Figure Summary of sulfate expansion of concrete containing 45 percent fly ash. Effect of Fly Ash Content. Concrete contain 35 and 45 per cent fly ash, by volume, was cast to investigate of the fly ash content on the sulfate resistance of concrete.
Liu et al. [8, 9] demonstrated that fly ash could increase the deterioration of concrete partially immersed in sulfate solution, and indicated that chemical sulfate attack rather than sulfate salt.
This partial replacement of portland cement with apozzolan such as low calcium fly ash, ground granulated blast furnace slag, or silica fumeequally reduce the potential for sulfate attack.
These pozzolans consume the calcium inthe pore water, reduce the total mass of. The consequences of sulfate attack include not only disruptive expansion and cracking, but also loss of strength of concrete due to the loss of cohesion in the hydrated cement paste and of adhesion between it and the aggregate particles.
Sulfates combines with the C-S-H, or concrete paste, and begins destroying the paste that holds the concrete. the fly ash will be in terms of reducing the heat of hydration (Thomas ), controlling expansion due to alkali-silica reaction (Shehata ), and providing resistance to sulfate attack (Shashiprakash ).
These issues are addressed in sections Effect of Fly Ash on. Fly ash increases the cementitious compounds, minimizes water demand, and reduces bleed channels – all of which increase concrete density. These factors yield concrete of low permeability with low internal voids.
Durability is increased with regard to freeze-thaw damage and disintegration from attack by acids, salts or sulfates. Technical Bulletin 6File Size: KB. The partial replacement of cement by fly ash is recognised as effective in giving increased resistance to attack by sulphate in groundwater and soils.
BRE Digest allows fly ash/cement for almost all groundwater and soil conditions for which sulphate-resisting cement is allowed, and draft ENV X also allows fly ash/cement within defined Cited by: Fly ash also improves the resistance of concrete to Na 2 SO 4 attack.
This effect is not simply the consequence of dilution of PC, since replacement with sand increases expansion. Unlike PC, whose sulfate resistance is relatively insensitive to the duration of curing, the effectiveness of fly ash is highly dependent on curing time, with longer curing periods yielding higher resistance.
In pursuit of producing sulfate-resistant concrete, literature studies have demonstrated that use of enough quantities of fly ash, in particular low-calcium or class F fly ash, can effectively increase resistance of concrete to chemical sulfate attack,.Cited by: Fly Ash Slag Geopolymer Concrete: Resistance to Sodium and Magnesium Sulfate Attack However, the same exposure to Na 2 SO 4 increased the observed FA/GBFS resistance while reducing the mechanical resistance of OPC by 30%.
This relates to their respective expansion percentages of and % and the presence of expansive ettringite in. Fly ash makes concrete less permeable, and pipe containing it may be more resistant to weak acids and sulfates (Davis ; K.
Mather ). Factors pertaining to the life of concrete pipe exposed to sulfate attack include the type of cement, chemistry of fly ash, quality of concrete, bedding and backfill used, groundwater, sulfateFile Size: KB. RESISTANCE TO CORROSION, ALKALI SILICA REACTION, AND SULFATE ATTACK Durability of concrete is a key consideration in the design of structures and pavements.
Longer lasting concrete structures require fewer repairs over their service life, thus resulting in lower life cycle costs. Increased service life translates to reducedFile Size: KB.
The results of this study revealed improvements in concretes’ resistance to sulfate attack by replacing a portion of cement with fly ash. The improvements, however, were not as much as expected for class F fly ash.
The optimum replacement level was different for different cement by: Some authors studied the effect of fly ash on the resistance of concrete/mortar to sulfate attack and pointed out that using sufficient amount of fly ash, especially low-calcium or F class fly ash.
Fly Ash Slag Geopolymer Concrete: Resistance to Sodium and Magnesium Sulfate Attack Article in Journal of Materials in Civil Engineering 28(12) July with Reads.Dense fly ash concrete helps keep aggressive compounds on the surface, where destructive action is lessened.
Fly ash concrete is also more resistant to attack by sulfate, mild acid, soft (lime hungry) water, and seawater. Reduced Sulfate Attack.
Fly ash ties up free lime that can combine with sulfates to create destructive expansion.L. Lemay, in Coal Combustion Products (CCP's), Fly ash concrete.
Increased strength: Fly ash, when used in concrete, makes structures like highways, bridges, tunnels, and buildings stronger and more durable (Vanita, Gupta, & Sachdeva, ).The ultimate compressive strength of fly ash concrete, due to the pozzolanic reaction, continues with time and is generally higher than.