Modified PVA Fiber To Enhance Engineering Life

Cement is an important raw material for preparing cement mortar, concrete and various cement products. It is one of the most important building materials in civil engineering. Although cement has good strength and constructability, cement mortar, concrete and its products have defects of poor crack resistance, which are prone to dry shrinkage cracks and temperature cracks. These cracks are constantly changing and developing over time, and the tiny cracks are expanding and eventually developing into larger cracks. Therefore, the research on the performance and application of anti crack modified cement is of great significance for improving the performance and durability of engineering structures.

The high strength and high elastic modulus PVA fiber used in concrete has the advantages of high strength, high modulus of elasticity, low elongation and good dispersibility. It also has the characteristics of acid resistance, alkali resistance, salt resistance, abrasion resistance and corrosion resistance. It is nontoxic, pollution-free and harmless to human body. It has good affinity and combination with cement based materials. It is an excellent crack resistant, anti-seepage and reinforced material for cement concrete.

At present, in China's asphalt pavement, the "strong base thin surface" theory is widely used, and the semi-rigid base of cement stabilized crushed stone is widely used. The cement stabilized macadam base after the completion of the construction is affected by the drying shrinkage stress, temperature shrinkage stress and the upper load stress. The local stress concentration phenomenon is prone to occur in the base layer, resulting in cracks at the weak connection point. This is also one of the important reasons for premature pavement damage in China.

It is found that adding PVA fibers into cement stabilized macadam mixture to form crack resistant base can improve this phenomenon. Fiber and cement stabilized macadam Mixture The adhesion strength between the interface increases the plastic tensile strength of the material against cracking, so that the cracking state of the cement stabilized macadam can be reduced or even disappeared.

stay Hefei In the experimental study of the anti cracking base course of Xinqiao International Airport Expressway, the anti cracking base course uses a polyvinyl alcohol fiber with cement length of about 20mm ~ 30mm in the cement stabilized macadam, with a dosage of 0.9 kg/m3 to 1.2kg/m3, so as to improve the crack resistance of the base.

Incorporation PVA fiber The cement stabilized macadam cracks are more than 90% above normal water stability, and the mix proportion and material requirements of anti cracking cement stabilized macadam are the same as those of normal cement stabilized macadam. In order to distribute the fibers evenly in cement stabilized macadam mixture, a mixing process should be added to the construction of normal cement stabilized macadam, anti crack and water stabilized macadam. Fiber length and volume have certain effect on compressive strength of cement stabilized macadam, but little effect.

Generally speaking, synthetic fiber concrete has been widely studied and applied abroad. At present, the use of synthetic fiber concrete in the United States accounts for 7% of the total volume of concrete, and the number of synthetic fiber concrete has far exceeded that of steel fiber reinforced concrete developed in advance. The further popularization and application of PVA fiber in engineering also requires the aging and fatigue tests under the condition of long-term use.