What is pozzolanic mortar?
A simple everyday definition of ‘pozzolan’ could be ‘a finely powdered material which can be added to lime mortar (or to Portland cement mortar) to increase durability and, in the case of lime mortars, to provide a positive set’.
Is Ggbs a pozzolanic?
A GGBS is NOT a pozzolan. The free vitreous silica, or silica aluminates like in the Pozzolanic ashes, is unwanted because it can contaminate the steel and render it useless. Nevertheless the combination of calcium / aluminum / silica / iron compounds is less reactive than in cement. The setting of GGBS is “very” slow.
What is pozzolana pozzolanic reaction?
The pozzolanic reaction is the chemical reaction that occurs in portland cement upon the addition of pozzolans. It is the main reaction involved in the Roman concrete invented in Ancient Rome and used to build, for example, the Pantheon.
What are pozzolanic mixtures?
Pozzolanic or Mineral admixtures refer to the finely divided materials which are added to obtain specific engineering properties of cement mortar/concrete. Popular examples of mineral admixtures are silica fume, fly ash, blast furnace slag etc.
What is the difference between pozzolan and pozzolana?
Note the difference with the term pozzolan, which exerts no bearing on the specific origin of the material, as opposed to pozzolana, which can only be used for pozzolans of volcanic origin, primarily composed of volcanic glass. …
What is pozzolana used for?
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.
What is Portland Pozzolana cement?
The Portland Pozzolana Cement is a kind of Blended Cement which is produced by either inter-grinding of OPC clinker along with gypsum and pozzolanic materials in certain proportions or grinding the OPC clinker, gypsum and Pozzolanic materials separately and thoroughly blending them in certain proportions.
Is sand a pozzolan?
Other Pozzolans The term “pozzolans” has extended to man-made aggregates and powders that have a similar hydraulic effect when blended with lime. Sand which has been quarried (pozzolana) requires one-fourth its weight of lime, while river sand or sea sand requires one third.
What are the pozzolanic materials in cement?
Pozzolanic cements are mixtures of portland cement and a pozzolanic material that may be either natural or artificial. The natural pozzolanas are mainly materials of volcanic origin but include some diatomaceous earths. Artificial materials include fly ash, burned clays, and shales.
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.
How is pozzolana made?
Pozzolana, also spelled pozzuolana, or pozzolan, hydraulic cement discovered by the Romans and still used in some countries, made by grinding pozzolana (a type of slag that may be either natural—i.e., volcanic—or artificial, from a blast furnace) with powdered hydrated lime.
Why do you use pozzolans instead of cement?
Replacing some of the cement with pozzolans preserves the mix proportions. Pozzolans replace cement pound for pound. Depending upon the particle size, chemical composition and dosage, different pozzolans will affect the concrete strength differently and at different times during curing.
How to make dry shrinkage of pozzolanic materials?
Place the dry paddle & the dry bowl in the mixing position in the mixer, then place all the mixing water in the bowl. Add the pozzolanic mixture to the water, then start the mixer & mix at the slow speed (140±5 rev/min) for 30 seconds.
What kind of materials do pozzolans react with?
Pozzolans are silicate-based materials that react with (consume) the calcium hydroxide generated by hydrating cement to form additional cementitious materials.
How does lime and pozzolans work together?
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