Bond strength of steel reinforcing bars ASTM A944

Scope:

Using beam-end specimens, the ASTM A944 test method outlines procedures for determining the relative bond strength of steel reinforcing bars in concrete. The standard looks at the bonding behavior of reinforcing bars and concrete following a fire. This test method has the advantages of being reliable, simple, low-cost, and easily adaptable for usage in both an underground and laboratory setting.

Test Procedure:

For ASTM A944, a tensile load is applied to the test bar. The loading rate shall be such that failure will not occur prior to 3 min after starting to load the test specimens. The load rate should be between 10% to 33% of the bond strength per minute and then at least 10 intermediate displacement and load readings should be taken. Data recorded for a test includes minimum load, initial load, displacement readings, and maximum load.

 Specimen size:

ASTM A944, beam-end test specimen consists of the test bar cast in a block of reinforced concrete which is (600 ± 25 mm) long. 

Data:

Bond strength is reported in inch-pound and is considered as standard. The test result underlines the need to modify the experimental approach, in order to be able to realistically predict the performance of the steel-to-concrete bond.