What are the advantages of pozzolanic materials?
The advantages of using pozzolans in concrete include the following: (1) material cost reduction when a part of the cement is replaced by pozzolans, which are low cost (with some of them being natural or industrial by-products/wastes) and pollution free; (2) environmental cost reduction in relation to reducing the …
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What are the advantages of pozzolanic materials?
The advantages of using pozzolans in concrete include the following: (1) material cost reduction when a part of the cement is replaced by pozzolans, which are low cost (with some of them being natural or industrial by-products/wastes) and pollution free; (2) environmental cost reduction in relation to reducing the …
What are the advantages of using pozzolana as an admixture in concrete?
Pozzolana used as an admixture in concrete has the following advantages:
- It improves workability with lesser amount of water.
- It increases the heat of hydration and so lets the concrete set quickly.
- It increases the resistance of concrete to attack by salts and sulphates.
- It leaches out calcium hydroxide.
What is the use of pozzolanic cement?
Portland Pozzolana Cement (PPC) It can be confidently employed in construction of hydraulic structures, marine works, mass concreting such as dams, dykes, retaining walls foundations and sewage pipes. It is also suitable for use in common applications such as masonry mortars and plastering.
What is pozzolanic admixture?
Pozzolanic or Mineral admixtures are basically derived from other substances, not chemically manufactured. Popular examples of mineral admixtures are silica fume, fly ash, blast furnace slag etc. Mineral admixtures have different roles to play in the concrete mix and enhance various properties of the concrete.
What is pozzolanic material What benefits can be achieved by using pozzolana with cement in concrete?
Pozzolans can be used to control setting, increase durability, reduce cost and reduce pollution without significantly reducing the final compressive strength or other performance characteristics.
What are the advantages and disadvantages of pozzolana?
Disadvantages of Portland Pozzolana Cement (PPC):
- Less rate of development of strength initially than ordinary Portland cement. ADVERTISEMENTS:
- It reduces the resistance to corrosion of steel reinforcement due to alkalinity reduction. But it improves permeability of concrete considerably.
- Setting time is longer.
How can the modulus of elasticity for concrete be improved?
As age of the concrete increases, concrete gains more and more compressive strength, so modulus of elasticity improves as the age increases. Also, with the increase in age creep in concrete decreases which improves modulus of elasticity.
What is pozzolanic concrete material?
A pozzolan is a siliceous or siliceous and aluminous material that in itself possesses little or no cementitious value but will, in finely divided form and in the presence of moisture, chemically react with calcium hydroxide at ordinary temperatures to form compounds having cementitious properties.
What is pozzolanic action?
From Wikipedia, the free encyclopedia. The pozzolanic activity is a measure for the degree of reaction over time or the reaction rate between a pozzolan and Ca2+ or calcium hydroxide (Ca(OH)2) in the presence of water.
What are the different pozzolanic materials used in concrete?
Pozzolanic materials may be divided into two groups:
- Natural Pozzolanic Materials: Under this group following materials can be grouped: Calcined diatomaceous earths. Volcanic ash, tuffs and pumicites. Opaline cherts.
- Artificial Pozzolanas: Under this group following substances are grouped: Silica fume. Fly ash.
What is pozzolanic explain various pozzolanic materials?
A pozzolanic material is by definition capable of binding calcium hydroxide in the presence of water. Therefore, the chemical measurement of this pozzolanic activity represents a way of evaluating pozzolanic materials. This can be done by directly measuring the amount of calcium hydroxide a pozzolan consumes over time.
What is the disadvantage of PPC cement?
Disadvantages of Portland Pozzolana Cement The initial strength obtained is less, which effect the de-shuttering of supports early. As it contains more fine material, handing of concrete is difficult.
Why are pozzolans used in concrete instead of cement?
The propensity for alkali-silica reaction (reaction with glass) is decreased, or even virtually eliminated Typically pozzolans are used as cement replacements rather than cement additions. Adding pozzolans to an existing concrete mix without removing an equivalent amount of cement increases the paste content and decreases the water/cement ratio.
What are the benefits of using pozzolans?
Pozzolans combine with the lime to produce additional calcium silicate hydrate, the material responsible for holding concrete together. By consuming the excess lime: The strength of the concrete is increased Its density is increased Efflorescence is decreased
How does pozzolanic reaction increase the durability of cement paste?
Initially the pozzolanic reaction is slow and thus the production of heat of hydration and development of strength is also slow. The reaction involves the consumption of Ca (OH) 2 and thus there is no production of Ca (OH) 2. The reduction of Ca (OH) 2 increases the durability of cement paste by making the cement paste dense and impervious.
What happens when you add more pozzolans to a mix?
In other words, adding more pozzolans to a mix changes the mix proportions. Replacing some of the cement with pozzolans preserves the mix proportions. Pozzolans replace cement pound for pound in good concrete countertop mix designs.
