Influence of Alkalinity and Ambient Temperature on Long-Term Properties of GFRP Reinforcement

Abstract

The article deals with the current problem of determining long-term reliability of non-metallic reinforcement in concrete structures. The alkaline environment of concrete with a pH higher than 12.0 affects the glass fibres degradative, whereas this degradation presents by reduction of their mechanical characteristics, resulting in a decrease in the tensile strength of the whole composite. The article summarizes the results of the ongoing experimental program so far, which aims to quantify this influence.

Degradace tahové únosnosti tvarované kompozitní výztuže vlivem alkalického prostředí

“…Dochází k urychlení procesu stárnutí kompozitu [16], [17]. Ve studiích [11] a [12] bylo poukázáno na fakt, že lázeň s teplotou cca 60 °C může u výztuží s nižší kvalitou vytvrzení matrice způsobovat nejen urychlení samotného testu, ale také nežádoucí degradaci mechanický vlastností, což v důsledku zkresluje dosažené výsledky. Je proto vždy nezbytné uvážit, jaké reálné teplotě bude výztuž v průběhu životnosti vystavena (tj.…”

Effect of Alkaline Environment on Mechanical Properties of Molded Composite Reinforcement

“…When performing degradation tests, the ageing process of the composite can be accelerated [16], [17] by the temperature of the environment in which the reinforcements are placed. In studies [11] and [12], it was pointed out that a bath temperature of about 60 °C can cause not only an acceleration of the ageing of specimens, but also an undesirable degradation of the mechanical properties of reinforcements with lower-quality matrix curing, which consequently distorts the results obtained. It is therefore always necessary to consider the actual temperature to which the reinforcement will be exposed during its service life, i.e., whether the temperature is close to the glass transition temperature of the matrix Tg.…”

The Fatigue Behaviour of GFRP Bars - Experimental Study

“…In addition to the level and nature of the load, an important factor that potentially negatively affects the long-term characteristics of the composite material is the alkaline environment, the humidity and the temperature, which generally reduce the tensile strength of FRP reinforcement [5,6]. Even with relatively small displacements in the contact of reinforcement and concrete during cyclic loading, the surface treatment and outer layer of the matrix are impaired due to abrasions from sharp edges of concrete aggregate.…”