Weathering Regions for Concrete Aggregates in United States (ASTM C33)

ASTM C33 provides maximum permissible limit for deleterious substances of coarse aggregates of concrete. This classifies coarse aggregates depending on severity of weathering. We will discuss about classification of coarse aggregates based on this in our upcoming posts; here our concern is weathering regions within United States. The weathering regions according to this standard are shown below:

The following guidance should follow while using this map:

1. This map shows only a guidance for probable severity of weathering for the regions shown in the map and use for coarse aggregate.

2. When a construction site lies on the boundary of regions of weathering, specifier should consult with local weather bureau to collect records about

• Amount of precipitation in winter of that region


• Frequency of freezing and thawing cycle

These records provide guidance to examine coarse aggregates under expected identical field conditions.

-When altitude of construction exceed 500 ft above mean sea level, it is considered that more severe weathering will be experienced than shown in corresponding region in the map

-When construction project is located in arid regions, it is considered that less severe weathering will be happened corresponding to region shown in the map.

-When confusion arisen in selecting weathering region, more severe region of weathering is chosen to remain in safer side.