Recently, polymer-modified mortars and rust-inhibitors have widely been used as repair materials for reinforced concrete structures. The purpose of this study is to make clear the corrosion-inhibiting property of the polymer-modified mortars with the rust-inhibitors and the effectiveness of the treatment of bonded concrete surfaces around reinforcing bars (rebars) with the rust-inhibitors in repairing works for such concrete structures.
Polymer-modified mortars using three types of cement modifiers with variation of rust-inhibitor content are prepared, and two types of specimens 40×40×160mm embedded with rebars of φ10×130mm are molded as follows:
(1) Type A Specimen: A rebar is completely embedded in a polymer-modified mortar in the specimen.
(2) Type B Specimen: Each half portion of a rebar is filled with a cement mortar and a polymer-modified mortar in the specimen. Sometimes, the bonded surface of the cement mortar is treated with a rust-inhibitor.
The specimens are cured, and subjected to accelerated corrosion. After that, the corroded areas of the rebars are measured to evaluate the corrosion-inhibiting property of the polymer-modified mortars and rust-inhibitor. The conclusions obtained from the test results are summarized as follows;
(1) The corrosion-inhibiting property of the polymer-modified mortars is improved with the addition of the rust-inhibitor.
(2) In Type B specimens using the base mortar without the rust-inhibitor, the addition of the rustinhibitor causes a maked decrease in the corrosion rate of the rebars in the repair mortar and an increase in that of the rebars in the base mortar.
(3) In Type B specimens using the base mortar with the rust-inhibitor, the use of the repair mortars with the rust-inhibitor causes a rust inhibition of the rebars in the base mortar.
(4) In Type B specimens with the bonded mortar surfaces treated with the rust-inhibitor, the corrosion rate of the portions of the rebars close to the treated mortar surfaces decreases and that of the end portions of the rebars increases markedly.