UBC Theses and Dissertations
Properties of fiber reinforced concrete with latex modification Xu, Hanfeng
Polymer modified cement-based materials and fiber reinforced cementitious composites are both widely used in civil engineering applications. Both show great advantages, especially in repair and rehabilitation. The work reported here, however, deals with polymer modified fiber reinforced cement based composites (PM-FRC), that is, the combined use of fibers and polymers in the same system. Although they have excellent bonding properties and durability, the relatively low toughness of polymer-modified concretes is still a concern for practical applications under seismic loading or severe service condition, especially for high strength concrete. In this research project, a commercial styrene butadiene latex was used to produce a concrete matrix with a compressive strength ranging from 70 to 80 MPa; a deformed steel fiber and two synthetic fibers (a polypropylene fiber and a blended polypropylene-polyethylene fiber), were incorporated in the matrix to optimize a high performance concrete in terms of flexural toughness. The results show that the high strength concrete made with latex (HSPMC) still failed in a brittle manner, although some ductility was observed. Synergistic effects between the fibers and the latex were observed in most of the composites over a wide range of deflections, as long as suitable polymer dosages were used. However, steel fibers appeared to be more compatible with the latex modified concrete in terms of both load-carrying capacity and toughness. The effects of fiber content and latex dosage are discussed, based on the results of analyses of toughness tests carried out according to ASTM C1018 and JSCE SF4, as well as the post-crack strength (PCS) procedure. It is concluded that a high performance composite with steel fibers and polymers could be a promising material for both structural and repair purposes.
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