Research On The Properties Of Polymer Cement Mortar With Polycrylonitrile Fiber

As the construction of civil engineering is developing rapidly in China, new construction projects increase. At the same time, repairing and reinforcing the structure existed has aroused great attention from the engineering sector. The structural failure and function loss caused by various reasons not only affect people's normal life, but also bring enormous economic losses. Therefore, developing new materials suitable for surface repairing and strengthening of concrete, extending the service life of buildings and reducing the maintenance cost are significant. The cement-mortar of polyacrylonitrile (PAN) fiber polymer studied in this paper is a high-performance composite mortar with high flexural strength, high adhesive strength and small contraction. It is also a new repairing and strengthening material with high performance.The influences, from polymer gelatine powder and PAN fiber, on workability and physical mechanical properties of mortar were studied in this paper. Appropriate dosage of PAN fiber and gelatine powder selected properly was confirmed. Based on this, further study on adhesive property, dry-shrinkage performance and frost resistance of fiber polymer cement-mortar were taken and related mechanisms were analyzed.The results showed that the polymer gelatine powder could increase the flexural strength of mortar, improve the flexibility but decrease the compressive strength of mortar. P1 improved with a better effect and its appropriate dosage was between 1.0% and 1.5%. Adding PAN fiber to the polymer mortar could make a further improvement to the construction workability of the fresh mixed mortar. In addition, the water holding capacity became better when the fiber dosage increased, with no bleeding phenomenon. When the dosage was at a suitable range, PAN fiber could improve the flexural strength and flexibility of the polymer mortar, but had little effect to the compressive strength. When the dosage of gelatine powder was between 1.0% and 1.5%, the dosage of PAN fiber was between 0.8% and 1.0%, the fiber polymer cement-mortar had the best comprehensive performance. Polymer gelatine powder could also improve the tensile adhesive strength of mortar and obviously improved when its dosage was between 1.0% and 2.0%. Compound doped the polymer gelatine powder and PAN fiber, the adhesive property of mortar became better. Besides, the adhesive strength improved as the dosage of fiber increased. Polymer gelatine powder and PAN fiber could also reduce the dry-shrinkage rate and improve the frost resistance of mortar. The dry-shrinkage rate reduced by 16.7% of the polymer mortar while 25.1% of the fiber polymer mortar, compared with ordinary mortar. After 30 freeze-thaw cycles, the flexural strength lost 28.9% of ordinary mortar,12.8% of mortar single-doped polymer gelatine powder with 1.5% dosage, while just 7.8%-10.1% of mortar double-doped polymer gelatine powder and PAN fiber.