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The Difference of Various Composite Manhole Covers

The Difference of Various Composite Manhole Covers
With the rapid development of urban and rural construction, the demand for well covers for new residential buildings and roads has increased sharply. The cost of traditional cast iron manhole covers is high, and theft is serious. When pedestrians are injured and vehicles are damaged, it has been troubled. The problems of the construction sector. In order to solve these problems, the corresponding departments have developed Composite Manhole Covers, and there are many types. Below Weijia Environmental will give you a detailed description of the performance comparison of various composite manhole covers.
Composite manhole covers can be broadly divided into five types: steel fiber concrete manhole covers, magnesite cement manhole covers, recycled resin composite manhole covers (silicone manhole covers), BMC molded manhole covers, and continuous reinforced composite manhole covers. The following is a comparison of the performance of five composite manhole covers.

composite manhole cover
1. Steel fiber concrete manhole cover
The steel fiber concrete manhole cover was improved on the basis of the reinforced concrete manhole cover. Due to the strong material and insufficient strength, the steel fiber with a length of 10-30mm is added to the concrete to improve the overall strength of the concrete material, and the bearing capacity is increased compared with the ordinary reinforced concrete manhole cover. Due to the serious phenomenon of chipping during use, manufacturers often add a metal frame outside the manhole cover to protect them.
Advantages: A, anti-theft; B, cheap
Disadvantages: A, insufficient carrying capacity, combined with the attenuation of cement strength, easy to break; B, too bulky, difficult to open.
Second, magnesite cement manhole cover
Magnesite cement is an inorganic material formed by mixing lightly burned magnesia, magnesium chloride and water in a certain ratio. The composite material based on magnesite cement is unstable, and the strength tends to decrease continuously under wet conditions. Even if the moisture-proof problem is solved, since the material is a crystal structure with a large amount of crystal water, when the air is dried, it tends to be powdered due to water loss, and finally, it has no bearing capacity. In 2003, a 9-year-old boy in Harbin was drowned in a well, which was drowned in the well. At the time, the manhole cover was made of magnesite cement as the base material and made of bamboo fiber as a reinforcing material. When the manhole cover is just produced, the bearing capacity is high, but in the course of use, the bearing capacity is lost due to the loss of crystallization water and pulverization.
Advantages: A, anti-theft; B, cheap
Disadvantages: A, insufficient carrying capacity; B, material is unstable, the carrying capacity of the manhole cover will continue to decrease during use.
Third, recycled resin composite material cover (silicon plastic manhole cover)
It is a thermoplastic composite material which is mixed and pressed in a molten state by using waste plastic and fly ash. The idea of making a manhole cover from this material is very good: recycled plastics are cheap, and fly ash is a material used by state taxation. Therefore, this project has been widely promoted and applied throughout the country. No fiber reinforcement
The material has insufficient bearing capacity, and is added with thermoplastic material (ie, softening and melting by heating). When the temperature is high, the vehicle is repeatedly crushed, and the manhole cover will continuously generate creep, which causes the middle part of the manhole cover to sink continuously, and finally falls off to form a ratio. The hole in the manhole cover is slightly smaller, forming another form of trap.
Advantages: A, anti-theft; B, cheap.
Disadvantages: insufficient carrying capacity, can only be used in green belts, etc. IV. BMC molded manhole cover
BMC (Block Molding Compound) is a molding compound pre-formed with an unsaturated resin as a base material, a 30-50 mm short fiber as a reinforcing material, and a calcium carbonate as a filler. The BMC molded manhole cover is formed by adding molded plastic to the steel bar under a certain temperature and pressure. The manhole cover is made of short fibers (30-50mm short fiber forming composite material has a strength of only 20-30% of continuous fiber), and the bottom cover structure is slab bottom rib, which is caused by the reinforcement material and the manhole cover structure. The bearing capacity of the manhole cover is seriously insufficient, and only the steel bars can be added to load. The addition of steel bars has two major defects: 1 rust on the surface of the steel bar, which often leads to poor bonding of the material interface, affecting the performance of the composite material; 2 metal material in the steel bar, BMC is a non-metal material, and the difference in thermal expansion coefficient between the two materials (The thermal expansion coefficient of BMC is about twice that of metal). At different temperatures (early, medium, late, winter, summer), the material interface will form stress, and the repeated rolling of the vehicle will cause the steel bar to detach from the BMC, and finally the bearing capacity of the manhole cover will be significantly reduced.
Advantages: A, anti-theft; B, exquisite appearance
Disadvantages: A, insufficient carrying capacity; B, due to the addition of steel bars, the interface will be detached, resulting in a significant decline in carrying capacity.
V. Continuous fiber reinforced composite manhole cover
The composite manhole cover is made of unsaturated polyester resin as the base material, and continuous glass fiber is used as the reinforcing material, supplemented by a certain rigid material. The material is divided into upper and lower layers. The upper part is made of wear-resistant and aging-resistant materials. The product has a long service life. The lower part is reinforced with continuous glass fiber. The manhole cover can be used with sufficient load-bearing capacity without reinforcing steel. It is a material manhole cover with better comprehensive performance in several composite manhole covers.
Advantages: A, anti-theft; B, high carrying capacity; C, beautiful appearance Disadvantages: complex manufacturing, high cost.

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