About the concrete manhole
Concrete is one of the most commonly used construction materials and is made of three main components of cement, water, and grain materials (gravel and sand). In addition to mentioned principal components, some materials such as pozzolans, additive material, and semi-cement materials can be added to it to correct and improve concrete properties. Availability of basic materials of concrete and their low cost are some properties that have made concrete popular and caused it to be used in the construction of structures, dams, bridges, highways, and tunnels.
Concrete manholes have been made in the historical trend of construction of manholes, high cost, and theft incidence of cast iron manholes. On other hand, due to the lower strength of concrete compared to cast iron, concrete manholes should be constructed with a thicker material section and therefore will have more weight compared to cast iron manholes.
Concrete manholes are built-in circular, rectangular and square shapes. By considering its application and manhole opening dimension, these manholes can be produced and used in different dimensions. However, the most used types of circular concrete manholes (which are installed on sewage and telecommunication manholes) are manholes with diameters of 30, 40, 60, and 80 centimeters.
The weight and price of concrete manholes
The weight and price of a manhole are always the most important factors that buyers consider when selecting a manhole to purchase. Concrete manholes have more weight compared to composite, polyethylene, copolymer, and Nano-composite manholes and almost, are considered the heaviest manholes. Among different types of manholes, only the cast iron type has more weight compared to concrete manholes with similar dimensions. But, because the concrete had lower strength than cast iron, concrete manholes should be built in more thickness to tolerate the proposed traffic load. Therefore, if we are looking at the problem from the bearing load capacity aspect, the concrete manholes are even heavier than cast iron manholes.
A concrete manhole is almost cheaper than any other type of manhole except Nano-composite manholes. This property is considered one of the main advantages of the concrete manhole in competing with other manholes. The price of cast iron manholes which are common in the market is more expensive than concrete manholes. Other properties of a concrete manhole are its anti-theft characteristics and its strength against rusting and sunlight conditions. However, these manholes have a serious weakness against frost and defrost cycles, sulfate, and chloride environments.
Concrete manhole standards
European standards of EN 124 and American standard of ACI have been used in the production of the concrete manhole.
