Due to the interest to increase the durability and sustainability of concrete structures and construction techniques, a wide range of novel cementitious materials are being designed and investigated. One such recent material is a cementitious material containing superabsorbent polymers (SAPs) studied only from 1999 onwards, mainly for its internal curing purposes with mitigation of autogenous shrinkage and sealing characteristics. Other positive influences are the change in rheology, the increase in freeze-thaw resistance, amongst others. From 2010 onwards, a combination of addition of synthetic microfibers and SAPs was studied, for their improved influence on autogenous healing in cementitious materials. It was found that optimal self-healing features were possible, as the crack widths were limited and water was available during dry periods. Some of those first samples now have an age of over 10 years.
As the autogenous healing capacity is dependent on the age of the material, so will be the possible influence of added materials to promote this healing. The effects beyond one year are not omnipresent in literature. The effect of the age cannot be investigated as long as the actual specimens do not reach the required maturity. In a previous study, the age was studied up to 8 years’ time. In this study, specimens from the same batch were studied after a decade of maturing in different storage conditions.
Typical strengths and crack widths were obtained. Due to the stress initiator property of SAPs, the number of cracks increases. Due to the macro-pore formation, the strength is lowered. However, the healing ratios are always higher for SAP compared to REF samples. This is due to the water action by the SAPs during dry periods and the ability of SAPs to extract moisture from the ambient environment. This leads to better conditions for healing products to form as water is available. The main visual appearance of the healing products was the whitish calcium carbonate crystallization.
The small crack widths after 10 years are still able to be partially healed. The main visual healing product is calcium carbonate. Further hydration was less likely as most binder already hardened during storage conditions. Generally, the samples containing SAPs show more prominent healing and they are still able to swell almost completely after a decade storage in an alkaline cementitious environment. This makes them a sustainable option for the future as less maintenance and repair will be required.
