A novel bio-based curing compound for cement-based materials

Abstract

Most concrete structures are designed to last for at least 50 years or more. During their lifetime these structures are exposed to various environmental actions. On going cement hydration guarantees a stronger concrete in terms of bond between the aggregates, fewer voids, and depercolation of capillary pores, which is of particular importance for cover concrete. Thus, a properly cured cement-based material is the ultimate preparation for a long service life, since it prevents the surface from drying. A new environmentally friendly, water-based curing compound, made of sodium alginate bio-polymers, has recently been developed at TU Delft that could help to achieve these goals. Experimental Rapid Chloride Migration tests and Environmental Scanning Microscope observations are conducted on different samples to investigate the functional properties, e.g. ion transport, and microstructural investigation, to examine the performance of the new bio-based curing compound. Mortar samples were cured at 50% RH and 20 °C both with and without surface addition of the bio-based compound. Two different types of cement, CEM I and CEM III/B, were tested to study differences in curing performance. Significant beneficial effects were observed at the mortar surface when applying the bio-based curing compound showing reduced diffusivity. The results showed a very good quality surface with a high quality and durable microstructure. Also, a higher curing sensitivity was observed for the CEM III/B samples compared to samples prepared with CEM I.