Bond Strength Between Reinforcing Steel and Different Types of Concrete

The present paper discusses bond strength between reinforcing steel and three types of concretes. The first type of concrete was concrete based on Portland cement. Two concretes were prepared - the first with a low content of cement and the second with a relatively high content of cement. The second type of concrete was alkali activated concrete, containing slag, and it was activated with a mixture of sodium water glass and potassium hydroxide. Similar concretes were prepared - the first with a low content of binder and the second with a high content of binder. Finally, the third type of concrete was designed using hybrid cement, containing slag and Portland cement, and it was activated with sodium carbonate. Similar concretes were prepared as in the previous cases. Bond strength was measured using the pull-out test. Usually, alkali activated concrete is considered to have a better bond with steel in comparison with Portland cement based concrete. The bond between hybrid cement based concrete and steel is very hard to evaluate. The results are important not only for the evaluation of bond between steel and concrete, but also for the development of alkali-activated or hybrid cement based steel-fibre concretes.