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Bearing Capacity of Composite Manhole Cover

Bearing Capacity of Composite Manhole Cover

In order to fundamentally solve the problem of serious theft of cast iron manhole covers for a long time, many manufacturers have developed many new anti-theft manhole covers from different materials. These composite well covers have little recycling value to avoid being stolen and attracted users'attention. With the development and successful application of composite well cover, users gradually recognize and accept it.

Over the past two years, the production enterprises of composite well covers have sprung up like bamboo shoots after a spring rain, and all kinds of material well covers have flocked to the top. Because there is no national high standard, the product quality is uneven, and hidden problems are constantly exposed, which makes the vast number of users worried. Even the users and authorities who just had some knowledge and interest in the Composite Manhole Cover were questioned.

In view of the above situation, we introduce and explain the composite manhole covers of different materials on the market at present.

1. Steel fiber reinforced concrete manhole cover: It is improved and developed on the basis of concrete well cover. Because of its brittleness and insufficient strength, steel fibers with length of 10-30 mm are added to concrete to improve the overall strength of concrete materials. Because of the serious phenomenon of edge collapse in the use process, a metal frame is mostly added outside the well cover to protect it. However, there are still some defects, such as insufficient bearing capacity, fragile, bulky, difficult to open, rough appearance and so on. In the actual production process, many enterprises did not add steel fibers, and users mistakenly believe that steel reinforcement is steel fibers.

2. Magnesium well cap: It is a kind of well cap which is composed of light burnt magnesia, magnesia and water in a certain proportion and reinforced with bamboo or wave fiber. Because the basic material is a crystalline structure with a large amount of crystalline water, it will be powdered due to the loss of crystalline water due to dry weather, and ultimately lead to no carrying capacity. In 2003, a 19-year-old child in Harbin fell into a well while playing on it and drowned. It was the same kind of manhole cover that was used at that time. The bearing capacity of this kind of well cover is higher when it is produced, but it will lose the bearing capacity when it is used because of the powdering of crystalline water.

3. Recycled resin composite well cover (silicon plastic, nylon well cover) is formed by mixing waste plastic or nylon with fly ash in the melting state. When the temperature is high, the thermoplastic well cover will gradually creep after repeated rolling by vehicles, which will cause the middle part of the well cover to sink continuously and fall off, forming a trap.        4. BMC Molding Cover: It is made of unsaturated resin as basic material, 30-50mm short fibers and reinforcing steel bars as reinforcing material, calcium carbonate as filling material, and pressed at a certain temperature. Because reinforcing bar is metal material and BMC is organic material, the thermal expansion coefficient of BMC is twice that of reinforcing bar, and because the surface of reinforcing bar is rusty, the interface between BMC and reinforcing bar is not firmly bonded. When the temperature changes, the interface between reinforcing bar and BMC material will form stress. In addition, repeated rolling of vehicle will lead to the interface separation between reinforcing bar and BMC. Finally, the cap loses its bearing capacity. And the surface is a mixture of BMC and calcium carbonate, so the wear resistance is poor. 

5. Glass Fiber Reinforced Composite Manhole Cover: From the structure of pot bottom structure (uniform load-bearing), compared with ribbed structure (centralized load-bearing), the stress area at the bottom increases several times; Secondly, multi-layer reinforcement, interlocking layers, uniform load-bearing, therefore, the structure makes the product more load-bearing capacity; From the material aspect, wear-resistant layer uses multi-color. Colored quartz sand is used as wear-resistant material and stabilizer is added to increase the wear-resistant life of products by several times. Continuous reinforcing fiber skeleton is used to ensure the high load-bearing capacity of products, while other composite well covers do not use fiber reinforcement, even when using fiber reinforcement, short fibers are used (the strength of short fibers is only continuous fibers). 20%-30%. When the strength is insufficient, we have to make up for it by reinforcing steel bar. The whole material of the product is organic material, and different reinforcing materials are used in different parts of the well cover. This avoids the separation and shedding of other composite materials due to reinforcing materials such as reinforcing steel bar. Layered composite technology is adopted to meet the requirements of mechanism innovation and material innovation. Different reinforcement materials are used in different parts of the well cover, which makes the separation and shedding of different reinforcement materials in different parts of the manhole cover.

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Contact: Elaine Yang

Whatsapp: +8613793332897

Email: sales04@coverchina.net

Add: No125 Liuquan Road Gaoxin District Zibo City,Shandong Province,China

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