Abstract
This study investigates the flexural behavior of normal-strength concrete (NSC) beams that were strengthened with no-slump, high-strength, high-ductility concrete (NSHSDC). A set of slant shear tests was performed to investigate the initial performance of the NSC substrate strengthened with NSHSDC. Slant shear tests considered two types of roughness of interface and five angles of the interface between NSC and NSHSDC. The test results showed that except for specimens with a 75° interface angle, the specimens with high roughness were conformed to the properties (14–21 MPa for 28 days) of the ACI Committee 546 recommendation. For flexural strength tests, NSC beams strengthened with an NSHSDC jacket on the top and bottom sides, three sides, and four sides resulted in strength increments of about 8%, 29%, and 40%, respectively, compared to the beams without NSHSDC jacket. Therefore, the use of NSHSDC is an effective method to improve the performance of NSC beams and is recommended for strengthening reinforced concrete members.
Highlights
Reinforced concrete is the most widely applied material for construction
To evaluate the bond strength of normal strength concrete (NSC) and NSHSDC interfaces, the mix proportions were based on 28 days of compressive strength of 45 and 120 MPa, as shown in Tables 1 and 2
The compressive strength tests results, which were evaluated in accordance with ASTM C39 [17] and four-point flexural strength test results, which were evaluated in accordance with ASTM C1609 [18], are shown in Table 5, The tensile strength of normal-strength concrete (NSC) was measured by a splitting tensile strength test (ASTM C496 [19]), whereas that of NSHSDC was measured by a direct tensile test, which used dog-bone-shaped specimens based on the JSCE (Japan Society of Civil Engineers, Tokyo, Japan) recommendations [12,13]
Summary
Reinforced concrete is the most widely applied material for construction. Economy, and ability to be formed and finished in various shapes make it a very appropriate construction material. Due to human errors, material disadvantages or changes in environmental criteria, a lot of structures need repairs and strengthening over their design service life. Strengthening of reinforced concrete structures has become very important for deteriorated reinforced concrete structures, but achieved much better under service. Previous research studies have used various types of concrete to strengthen reinforced concrete members, such as shotcrete jacketing, laminate jacketing, epoxy bonding, etc. All these methods have problems with bond strength of concrete to concrete, durability, ductility, and installation problems
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