Plaster Expanded Metal Technology for the Wall Anti-Cracks
Expanded metal plastering is to reinforce the frame structure wall.
Nowadays the frame structure is widely used on the building, such as residence, commerce, offices and so on. The advantages of the frame structure are big area, flexible and changeable. And the filling wall is the necessary enclosure design for the frame structure. It can not only meet the use function but also beautify and protect the main building structure. But the frame structure sometimes causes the cracks and the cavity on the wall. This article is about how to prevent the wall cracks with expanded metal and fiberglass mesh so that the building quality would be improved.
The reason that the wall filled with frame structure has cracks.
- The plastering material.
The concrete hollow masonry has high shrinkage and it's different to storage. The masonry would has cracks when it's used to build without fully shrinking.The plaster mortar is different from the masonry mortar and the shrinking degree is different too. This could cause cracks. And when the connecting is not firm there would also cause cracks and cavity.
The formula of the sand is not according to the standard. The silt content of the sand is out of the limit.
The variety and strength of the cement is not appropriate for the building. The slag cement of big shrinkage and pozzolanic cement would cause cracks. The common silicate cement also cause cracks. The gypsum mortar is too hard and it's difficult to handle.
The rust resistance layer is not eligible of the expanded metal. The fiberglass grid would get corroded by the alkalinity. The cracks and cavity would happen as time goes by. When the position of the reinforced mesh is not right, or the reinforced measure is not reasonable, the cracks would also happen.
Plastering material (cement mortar, gypsum mortar, mixed mortar) is brittle material and they are easily influenced by the temperature. There maybe the chap on the plastering layer.
The interface agent is not reasonable. The connecting is not firm if the amount of the agent is not precise. The plastering would cause cracks and cavity when the connecting is broken.
- The tools.
The mortar mixing machine is too old and it could not mix the cement evenly. The plastering layer would crack when we water the wall. The transport machinery could not run normally. The mortar maybe lose its active or gets hard when the mortar is transported to the construction site. So it would cause cracks when the improper mortar is used to plaster.
- The workers.
The operator doesn't pay attention to the quality and doesn't handle the machine according to the specified technology. The quality hidden danger would cause the cracks.
- The environment.
It's hot and dry so the wall would crack if the conservation is not enough. The plastering is not strong when the plastering layer is wet because of the rain before the plastering is solidified. If there is not antifreeze measure during winter, the plastering would crack because of frost damage. If the plastering layer is not solidified and is exposed to the heavy wind it would cause cracks. It would cause cracks if the plastering is hit heavily.
- Construction technology.
- Building the filler wall: It's fast to build the filler wall. But if the building height exceeds the standard and the wall doesn't settle well, there would be cracks when we plaster. The connecting between the shear wall brace and the wall is not firm. The position of some structures is not reasonable. The concrete of the top wall is flabby. The mortar is not full. All the above reasons would cause the cracks for the plastering layer.
- The base plastering: The surface of the concrete is smooth. The base plastering is not watered before plastering. The oil stain, maintenance liquid and dust is not cleaned. The reinforced structure measure is not reasonable. The connecting between the steel mesh and the plastering layer. The wall hole is not blocked. The strength of the plastering is different from the base wall.
- Plastering technology: The thickness is too thick when we plaster. The thickness is more than 35 mm and there is not expanded metal to reinforce the wall. The plastering layer is not close-grained and neat. The proportion of the cement and the mortar is not reasonable. The conservation time is not appropriate.
The measures for frame structure anti-cracking.
- The main reasons that the frame structure cracks.
- The workers don't according to the standard to build the frame structure and plaster.
- The filler wall gets deformed when the filler wall shrinks by itself.
- There is not reinforced measure on the connecting among different matrixes. Or we don't choose the right reinforced structure.
- The plastering material is not b enough to keep stable. It would be deformed as time goes by.
- The plastering layer loses too much water. The plastering is frozen in the winter. It's windy heavily by the plastering. The plastering is deformed under other press. The conservation is not on time.
- The measures for cracks.
- The workers.
We should strengthen management for the workers. We should communicate with the workers. We can use the production to tell the workers the goal that we want. We talk about the technology, process, the insures, the standard and the technical training. The examination of the mixing, base handling, plastering and the conservation should be in time so we could find problems and solve them in time.
- The machine.
We should check the blender and other machines on using and maintain the machines.
- The environment.
The conservation should be in time during the rainy season. The waterproof measure should be set before the plastering layer is solidified. The wind proof measure should be set when it's windy heavily.
- The material.
- The masonry should be stored at least for 28 days then is used to build.
- The material of the building mortar should be as the same as the plastering mortar.
- The material for the cement mortar is the normal Portland cement of strength grade 32.5. The proportion for the cement, water: bottom ash = 1: 3. The proportion for the mortar, water: surface ash = 1: 2.5. The content of the sand, mud and clod should not be more than 3 %. We should screen the cement and clean the sand.
- The wire diameter of the expanded metal is more than 1.4 mm. The mesh opening is less than 15 mm. The mesh opening is diamond. The material of the fiberglass grid is anti-alkali fiberglass cloth. The fiber is the environmentally friendly fiber.
- The workers.
- The construction technology.
- The filler wall: The plastering would start when the masonry wall is built for seven days. The shear wall brace should be more than 2 roots and it's wire diameter is 10 mm. The column is put per 4 meter and is connected with the wall. The column is 240 mm width and its thickness is as same as the wall. There are four steel bars whose wire diameter is 14 mm. The size of the hoop steel is 200 mm and its wire diameter is 6 mm. The distance between the steels is 100 mm on the both sides. The depth from the beam to the wall is more than 250 mm. The wall brace, steel and the steel bar column must be connected tightly with the embedded part.
- The base wall: Clear the oil stains, rust, curing solution and the left mortar. Water the wall and make conservation before plaster. We fix the concrete expanded metal panel with the iron panel of 1 mm nail pad. The expanded metal is fixed with the cement steel nail to the masonry. The thickness of the expanded metal that is covered on the frame structure should be more than 100 mm. When the plastering layer is more than 35 mm after watering the base surface, we should embed the steel bar of 10 mm wire diameter. And it's to install the expanded metal by layer. The expanded metal should be installed on the masonry before plastering.
- Plastering: The layer thickness is 5–7 mm. We should plaster layer by layer and keep the plastering neat and dense. There is fiberglass cloth on the broken plastering layer. The fiberglass mesh is put between the plastering layers. The fiberglass grid as reinforced layer is installed on the plastering connecting part. On the window is installed the fiberglass cloth to reinforced the window. To decrease the cracks, the alkali resistance fiber is added to the mortar.
- The conservation: In the summer, we should water the plastering layer after 8 hours or when the plastering is dry. We should use the nozzle water the plastering and make the conservation for at least seven days.
- The reasons for the cavity and wall cracks are mainly because the wall shrinks and gets deformed. The new masonry owns bright prospect for it's not easy to shrink and deformed.
- The efficient plastering material with low cost and the plaster expanded metal have bright prospect