types of artificial aggregate and pozolonic material
Answers
Natural aggregates consists of rock fragments that are used in their natural state, or are used after mechanical processing such as crushing, washing, and sizing. • Some natural aggregate deposits, called pit-run gravel, consist of gravel and sand that can be readily used in concrete after minimal processing.Pozzolanic materials may be divided into two groups:
1. Natural Pozzolanic Materials:
Under this group following materials can be grouped:
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.
2. Artificial Pozzolanas:
Under this group following substances are grouped:
1. Silica fume
2. Fly ash
3. Blast furnace slag