As a representative of the new manhole cover, the compound manhole cover has gradually realized the application from light manhole cover to heavy manhole cover. Composite manhole covers can be divided into BMC manhole covers and SMC manhole covers. The BMC manhole covers are mixed with agglomerated short glass fibers and mixed with a filler ratio resin. They are molded at one time at high temperature. It is difficult to make the bearing capacity of the BMC manhole covers meet the requirements using only short glass fibers. In this case, if the rebar is added to the manhole cover, the bearing capacity will be significantly improved. However, because the material of the steel bar and the composite material is very different, the difference in thermal expansion coefficient is relatively large. The surface does not bond well with the resin, and this approach is not ideal from a service life perspective. Therefore, BMC manhole covers are suitable for low-load areas, such as green belts, sidewalks, and non-motorized lanes. Then there is the SMC manhole cover. The SMC manhole cover is molded by continuous fiber reinforcement and filler molding. Compared with the short fiber reinforced BMC manhole cover, the continuous fiber reinforced SMC manhole cover has a greatly improved bearing capacity without the need for additional reinforcement. It is guaranteed, so the SMC manhole cover is suitable for high-load areas such as gas stations, freight stations, logistics parks, urban trunk roads, highways, terminals, and airport runways.
With the development of the country and the progress of society, the number of national cars has increased year by year, so the number of gas stations has increased year by year, and the use of manhole covers has increased year by year. Gas stations are flammable and explosive areas, so gas stations Manhole covers require flame retardant and antistatic features. This is not enough compared to traditional cast iron manhole covers, so composite manhole covers have become mandatory manhole covers for gas stations. Because the vehicles entering and leaving the gas station have large trucks, private cars, etc., the bearing capacity of the gas station manhole cover must meet the maximum load carrying capacity of the vehicle. The composite SMC manhole cover is very suitable. It not only has sufficient bearing capacity and resistance. It has the characteristics of anti-static and anti-static, and its material has no recycling value, which can prevent theft naturally and improve the safety of the gas station.