INTERFACE STRUCTURE AND PROPERTY OF WHEAT STRAW FIBER CEMENT-BASED COMPOSITES

The application of wheat straw fiber cement-based composites (WFCC) was restricted because of the poor mechanical properties and lots of extractives of wheat straw in cement paste, In order to overcome the natural defects of wheat straw, the wheat straw was modified respectively by different mass fractions of NaOH, Na(2)SiO(3) and H(3)PO(4) solutions. The results show that, the various indexes of wheat straw fiber that was soaked by NaOH solutions (mass fraction 5%) for 12 hours were optimal, and the extraction rate of impurities from wheat straw was 36.85%. Moreover, its ultimate tensile strength and fracture elongation were respectively increased by 104.81% and 78.57%. Meanwhile, the modified fiber bundles arranged densely without damage phenomenon in WFCC, and surface of fiber was covered in massive cement hydration products, and the interfacial adhesion between fiber and hardened cement paste was improved. Therefore, the flexural strength of WFCC with modified wheat straw was increased by 12.82%.