Title: Improving the Bond Strength of Concrete to Rein-forcement by Adding Methylcellulose to Concrete

Author(s): Xuli Fu and D. D. L. Chung

Publication: Materials Journal

Volume: 95

Issue: 5

Appears on pages(s): 601-608

Keywords: bond strength; carbon; cement; concrete; electrical resistivity; fiber; latex; methylcellulose; silica fume; steel;

DOI: 10.14359/402

Date: 9/1/1998

Abstract:
The use of methylcellulose (0.4 to 0.8 percent by weight of cement) as an admixture in cement paste or concrete was found to increase the shear bond strength with steel rebar, steel fiber or carbon fiber to values attained by using latex (20 percent by weight of cement) as an admixture, even though latex was used in a much larger quantity than methylcellulose. The bond strength increased with increasing methylcellulose amount. The contact electrical resistivity between cement and fiber or between concrete and rebar was increased by latex addition, but not changed by methylcellulose addition. The combined use of silica fume (15 percent by weight of cement) and methylcellulose (0.4 percent by weight of cement) as admixtures was found to give concrete that exhibited high bond strength to steel rebar, in addition to previously reported high tensile modulus, tensile ductility, flexural strength and flexural toughness; the bond strength attained was higher than that attained by using either silica fume or methylcellulose as admixture. Latex in combination with silica fume did not work due to low workability. Methylcellulose in combination with silica fume was effective due to silica fume promoting densification and methylcellulose promoting adhesion.