Polypropylene fiber can significantly improve The anti cracking performance of concrete, Then do you know Polypropylene fiber is how to do it?
First of all to find out the causes of concrete crack: crack loads directly caused by stress, which caused cracks according to the main stress of the conventional calculation; under external loading, cracks caused by structural stress: cracks caused by deformation, such as cracks caused by temperature and shrinkage and swelling, uneven settlement and other factors the. Usually the crack is by one or several factors and the formation of cracks, and the three factors, the deformation cracks caused by changes in accounting for more than 80%.
Well, look at Polypropylene fiber is how to deal with the concrete cracks! The polypropylene fiber in the control of concrete plastic shrinkage cracks of the main role: block the development of plastic shrinkage crack generation and crack limit. The survey found that plastic concrete cracking occurs mainly in concrete hardening before, especially in the pouring of concrete after 4 ~ 5 hours, this stage due to evaporation and moisture transfer, the tensile strain capacity of concrete is lower than the strain caused by shrinkage, thus lead to concrete plastic cracks.
If mixed with polypropylene fiber, polypropylene fiber with uniform distribution, similar to that of the screen function, slowing the cracks because of rapid dehydration of coarse aggregate produced by delaying the emergence of the first plastic shrinkage cracking time. When the crack appears, the existence of polypropylene fiber makes the development of the crack tip is restricted only to bypass the crack fiber or fiber rupture to continue to develop, which requires huge energy consumption to overcome the restriction of fiber fracture development, volume fraction of fiber is bigger, the stronger the limiting effect. But in the ordinary concrete crack tip without restriction to that effect, free development, which makes the crack in concrete cracks than adding fiber in concrete to wide, long.
The plastic shrinkage crack area of concrete crack, the maximum fracture width and water loss rate were increased with the increase of fiber volume content significantly decreased, which is effective for improving the anti cracking performance of concrete.