Synthetic superabsorbent polymers (SAPs) are used in concrete for various applications such as internal curing and frost resistance. However, the addition of these SAPs may lead to a significant decrease in mortar strength, especially when high amounts of SAP are necessary. This is the case for example when self-sealing and -healing of cracks is strived at. In order to overcome this bottleneck, the present work focuses on the application of biopolymers as SAPs. The work especially aims to evaluate the potential of both sodium alginate (NaAlg) as well as physically cross-linked calcium alginate (CaAlg) as SAPs to establish a sustainable approach towards self-sealing and -healing concrete without impairing mechanical strength. First, the swelling properties in both demineralized water and cement filtrate solution are tested. Subsequently, the mechanical properties of mortar mixtures in the absence and the presence of SAPs are compared by performing flexural and compressive tests. The alginates show a swelling capacity up to 72 times their own weight in aqueous solutions. Interestingly, they lead to a minor reduction in compression strength (up to 15% upon addition of 1m% SAP). These biopolymers show high potential for enabling concrete repair, more specifically, for the self-sealing and -healing of cracks without impairing the strength.