Brick classes discussed in last part according to BS 6100 are applicable where acid resistance; low water absorption and strength are the main criteria of construction. But there have other observation that-
If water absorption is less than 12%, difficulties arise to derive proper bond between brick and mortar.
Another classification of bricks is also available and very common in our usual practice. These are
a. First class
b. Second class
c. Third class
d. Kiln rejects
We will discuss about all these classification in our upcoming posts. Here we will discuss about only first class and second class bricks.
In brief first class brick have uniform shape and size and have minimum crushing strength 10.5 N/mm2. Of other important properties, water absorption should not be more than 15 percent of their dry weight.
Regarding second class brick, it has crushing strength 7 N/mm2 (minimum) and water absorption is not more than 22%.
Dear reader we have discussed about strength and water absorption of different types of bricks let us know about how disruption occurs in brick foundation due to water absorption?
The water remains in brick, when get frozen produce frost damage that materializes by splitting or exfoliation of outside surface or parallel to it. Sometimes cracks become large and continue which results total disruption of bricks.
The severity of damage depends on other environmental conditions like
b. Speed of freezing
c. No. of freezing-thawing cycles
Regarding frost resistance of brick we can include; it depends on
a. pore distribution
b. Water absorption
We have discussed about above material properties in earlier posts and as well in first portion of this topic. We hope you have an overall idea about frost deterioration/damage of foundation and foundation elements constructed with bricks.