The other arch beam is made of magnesium oxychloride cement and glass fiber. Although the cost is greatly reduced, it is easy to pulverize the damp bittern in a humid environment, which reduces its strength and may suddenly break and collapse, causing potential safety hazards.
In order to solve these technical problems, people have made some useful explorations. For example, the China utility model patent with the publication number of CN 10 1305680B, "A New Waterproof Greenhouse Support and its Manufacturing Method", discloses a technical scheme, in which glass fiber grid cloth is gradually pulled into a PVC pipe, while magnesium oxychloride cement is filled and maintained for 4-7 hours.
However, after the glass fiber grid cloth enters the PVC pipe, the distribution of its folds in the pipe is random and uncontrollable, especially when the PVC pipe is bent axially, that is, when the arch beam is made, the glass fiber grid cloth will be dense in the lower chord of the bending, while there is almost no other part, resulting in inconsistent strength of the whole arch beam and easy to break at the weak point; At the same time, because the fillers in PVC pipes are mostly filled with magnesium oxychloride cement, the finished products are very heavy, which is not conducive to transportation and construction; In addition, because the filler in the PVC pipe only consists of magnesium oxychloride cement and glass fiber mesh,
When it is used in large plastic greenhouses with high compressive and tensile strength requirements, in order to meet the strength requirements, it is necessary to increase the section size, which further leads to increased costs, waste of raw materials and difficulties in transportation and construction.
reference data
Encyclopedia. Baidu [reference time 20 18-4- 18]