Effect of super absorbing polymers on the freeze–thaw resistance of coloured concrete roads

This research project aims to improve the durability and resistance to freeze–thaw cycles of coloured concrete roads. The negative effect of the red pigment on the freeze–thaw resistance of concrete is studied and possible improvement actions are being considered and evaluated, for example, by adding super absorbing polymers (SAPs) to the fresh mix. SAPs can absorb water as much as 50 times of its own weight. The polymers also have the ability to gradually release the absorbed water during the self-desiccation processes in concrete during hardening and hydration, reducing the amount of desiccation cracks in the concrete. As a result, small cavities are created in the concrete due to the donation of absorbed water to the hydration process. These small pores can serve as pressure vessels to counteract the expansion of freezing (expanding) water inside saturated concrete during freezing. By means of a laboratory investigation the influence of the red pigment on the scaling and degradation due to freeze–thaw cycles is investigated by means of compressive strength tests, splitting tensile strength test, ultrasonic pulse velocity tests, weight loss measurements, porosity measurements, visual inspections and scanning electron microscopy (analysis). Secondly, the effect of different amounts and different types of SAPs added to the fresh mix is studied and evaluated by means of the previously mentioned testing equipment. An improvement of the freeze–thaw resistance of coloured road concrete is obtained by adding SAPs. By adding 0.26 wt% dry SAPs (wt% of weight of added SAPs relative to cement weight) to the fresh reference mix, the scaling and the internal damage after 30 freeze–thaw cycles is significantly reduced by 54% and 71%, respectively.