Effect of styrene butadiene latex polymer contents on the bond properties of macro polypropylene fiber in polymer-modified cement-based composites

Because of its hydrophobicity, macro polypropylene (PP) fiber does not bond well in cement‐based composites and can reduce the mechanical properties. This study evaluated the influence of styrene–butadiene latex polymer (0–25 wt %) on the bonding of macro PP fiber in these composites. Bond strength was determined using dog‐bone test specimens compliant with JCI SF‐8. The bond strength of macro PP fiber improved with increasing styrene–butadiene latex polymer (latex) content up to 15%. The elastic behavior of the precrack zone increased, and interface toughness increased because the debonded zone was strong after crack formation. For latex content above 20%, the latex retarded the hydration reaction due to the absorption of latex into cement particles. This resulted in bond strengths that were lower than those for composites prepared with up to 15% latex content. Microstructural analysis of the macro PP fiber revealed that the amount of scratches also increased with increasing latex content up to 15%. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012