Table of Contents
- 1 What happens when pozzolana is added to cement?
- 2 What are the properties of pozzolanic materials?
- 3 Why pozzolana is used in cement?
- 4 What is delayed ettringite formation in concrete?
- 5 What is the difference between pozzolan and pozzolana?
- 6 Is pozzolanic reaction with microsilica and lime possible?
- 7 What are the different types of pozzolanic materials?
What happens when pozzolana is added to cement?
The addition of pozzolana to ordinary Portland cement increases shrinkage but reduces the permeability of the concrete. Advantages: It increases the workability.
What is pozzolanic reaction in concrete?
The pozzolanic reaction is the chemical reaction that occurs in portland cement upon the addition of pozzolans. The pozzolanic reaction converts a silica-rich precursor with no cementing properties, to a calcium silicate, with good cementing properties.
What are the properties of pozzolanic materials?
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 the most important advantage of pozzolana and why does it have that property?
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 …
Why pozzolana is used in cement?
What does a pozzolan do in the concrete? A. Pozzolans reduce bleeding because of fineness; reduce the maximum rise in temperature when used in large amounts (more than 15\% by mass of cementitious material) because of the slower rate of chemical reactions; which reduce the rise in temperature.
How is pozzolanic activity measured?
Direct methods monitor the presence of Ca(OH)2 and its subsequent reduction in abundance with time as the pozzolanic reaction proceeds, using analytical methods such as X-ray diffraction (XRD), thermo-gravimetric analysis (TGA) or classical chemical titration.
What is delayed ettringite formation in concrete?
The term “delayed ettringite formation” (DEF) is commonly used to refer to the potentially deleterious reformation of ettringite in moist concrete, mortar, or paste after destruction of primary ettringite by high temperature.
What do Pozzolans do in concrete?
Pozzolans reduce bleeding because of fineness; reduce the maximum rise in temperature when used in large amounts (more than 15\% by mass of cementitious material) because of the slower rate of chemical reactions; which reduce the rise in temperature.
What is the difference between pozzolan and pozzolana?
As nouns the difference between pozzolan and pozzolana is that pozzolan is any material which, when combined with calcium hydroxide, exhibits cementitious properties; often used as an extender with portland cements while pozzolana is a type of volcanic ash used for mortar or for cement which sets under water.
Where is pozzolanic cement used?
Uses of Portland Pozzolana Cement
- Used in hydraulic structures, marine structures, construction near the sea shore, dam construction etc.
- Used in pre-stressed and post-tensioned concrete members.
- Used in masonry mortars and plastering.
- As it gives better surface finish, it is used in decorative and art structures.
Is pozzolanic reaction with microsilica and lime possible?
Pozzolanic reaction is already quite fast if you use correct ratio between microsilica and hydrate lime.
What are the practical consequences of the pozzolanic reaction?
A practical consequence of the pozzolanic reaction is the gradual hardening of pastes containing pozzolanic materials and lime.
What are the different types of pozzolanic materials?
1. Natural Pozzolanic Materials: 1. Calcined diatomaceous earths 2. Volcanic ash, tuffs and pumicites 3. Opaline cherts 4. Clay and shales Natural pozzolans need further grinding and calcining to activate them. Nowadays they have lost their popularity due to the availability of more active artificial pozzolans.
What is pozzolanic stabilisation?
Pozzolanic reactions consume part of the soil’s water content. This is preferable in terms of engineering performance of the stabilised soil, as the material becomes stiffer and less susceptible to volume shrinkage/swelling.