Highway Zwijndrecht Melsele
First application of 60% recycled granulates in substrate.
Road concrete
crushed stone 4/6,3 – 6,3/20 – 20/32
100 % natural sand
>375 kg/m3 CEM III/A 42,5 N LA
<0,45
Slipformpaver
The results of the control measurements met the requirements in the specifications. After only a few years, damage was observed in the form of localised chipping between nearby cracks, coupled with the phenomenon of horizontal cracking. The horizontal cracks did not occur at all at the interface of the two concrete layers (perfect solidary mixing was observed there), but rather at the level of the longitudinal reinforcement.
Based on literature review and on the analyses performed, it is strongly suspected that the use of concrete granulates in the substrate is at the root of the damage, owing to higher shrinkage and lower concrete strength.