About composite frame and manhole
Composites are materials that are made by combining two or several different materials in such a way that the properties of new materials are different from their composed materials. Composite materials mainly include a texture phase (matrix) and a filler phase, the second phase which makes a total of 5 percent of all materials improves the mechanical properties of the material and is a strengthener.
In the production procedure of manholes, after encountering some problems such as the high rate of cast iron manhole theft and also the high weight of concrete manholes, producers started to manufacture some manholes which are anti-theft and have low weight compared to concrete ones. In this step, composite frames and manholes appeared in the market. These manholes which are made from a combination of fibers, unsaturated resins, tint, calcium carbonate, some adhesive, and polymeric material, are increasingly used due to the higher number of benefits and problems of other manholes mentioned before. They are being used in different industries such as oil and gas, water and sewage, electricity and telecommunication, and also in some urban applications.
Due to the employment of composite manholes in different industries and having the capability of being produced in different shapes and sizes, these manholes are produced in circular, elliptical, square, and rectangular shapes in different sizes.
Price of composite manholes and their weight
As was mentioned, composite manholes were made to solve problems arising from the high weight of concrete and cast iron manholes. The weight of these manholes is different from the mentioned manholes because of manufacturing technology and their bearing capacity. However, generally, it can be said that their weight is almost 70 percent of the weight of concrete and cast iron manholes. The lower weight of these manholes is an advantage that decreases their transportation and installation expenses and makes their openings in the site easier. Due to having unrecyclable components, the theft rate in them is close to zero which is one of their advantages compared to theft problems in cast iron manholes. However, it should be mentioned that nowadays some manholes with less weight compared to composite types are built, which include Nano-composite manholes, polyethylene manholes, and copolymer manholes.
Besides the weight, the price of the manholes is another influential parameter in selecting them which varies depending on the manufacturing technology of the manhole and its bearing capacity. Composite manholes are more expensive than all other types of manholes such as cast iron, concrete, Nano-composite, polyethylene, and copolymer. Their higher price is one of their disadvantages. Other problems are their incompatibility with the environment and their detectability with detectors.
Composite manholes standards
Composite manholes are produced according to the European standard of EN 124. Other standards in this domain include:
ASTM D543 chemical resistance
ASTM D635 flammability and resistance against flame
ASTM D1501 resistance against sunlight
ASTM D570 water absorption rate
