Análisis experimental de la pérdida de adherencia hormigón-acero en hormigones sometidos a altas temperaturas

Abstract

Within the context of the most usual

construction materials for building and civil

infrastructures, concrete stands out because of

its excellent behaviour when exposed to high

temperatures and fire condition. The present

study focuses on the residual bond strength

between concrete and steel rebars after

exposure to elevated temperatures and natural

cooling to room temperature. Normal strength

and high strength concretes have been tested, as

well as polypropylene and steel fibre reinforced

concretes.

The bond strength has been measured using the

pull-out test. Compressive and tensile strength

have also been determined. Some specimens

have been tested at an age of 28 days and at

room temperature. At 60 days the tests have

been repeated at room temperature and after

heating up to three temperature ranges: 450°C,

650°C and 825°C. Before each of the three

heating phases, the specimens were pre-heated

during 3 hours at 120 °C.

After these experiments it has been possible to

assess the loss of steel-concrete bonding for

higher temperatures. The addition of fibres has

no clear influence on the bonding at ambient

condition. However, an improvement on the

residual bonding strength has been observed

for steel fibre reinforced concrete under high

temperatures.