Abstract
This paper gives a quantitative comparison of how different curing methods impact the rate of drying and subsequent penetration of lime water and chloride penetration of concrete. Laboratory work is used to investigate a bridge deck concrete mixture cured by two different curing compounds, wet curing of different lengths, and then no curing. The results confirm that wet curing methods reduce the ingress of external chemicals more effectively. The wet curing for even one day provided significant improvement over both curing compounds and no curing. To confirm the findings in the field eight bridge decks were investigated that were cured with a curing compound and wet curing. The field investigation confirms the findings of the laboratory testing and emphasizes the importance of wet curing for long term durability of concrete. This paper provides important quantitative data that can be used to compare these methods and help with making decisions about different curing practices and the impact on the service life of concrete.
1. Introduction
After casting concrete it is typically necessary to maintain sufficient moisture content on the surface to sustain hydration [1]. This process is called curing [2]. Maintaining the moisture in concrete promotes reaction of the binder to develop a torturous and strong microstructure [1–3]. A torturous microstructure will reduce the drying rate and the ingress of fluids and external ions. This means that curing can improve the long-term durability of concrete [4–6].
Wet curing continuously supplies moisture to the surface of the concrete [1,2]. However, there are challenges in curing concrete elements that dry from one side, such as pavements [2,7,8]. For example, concrete pavement in a dry environment can suffer from large differential drying shrinkage after the termination of wet curing which can lead to dimensional instability, called curling [9–13].
4. Conclusions
This work provides quantitative comparisons of the impact of different curing methods on the evaporation rate during drying, subsequent moisture uptake, and Cl penetration that can help practitioners decide how their construction practices impacts the durability of their concrete. The following conclusive remarks can be made:
- The samples that were uncured showed the worst performance of the investigated samples.
- Wet curing significantly reduced the mass loss during drying, mass gain from sorption, and the penetration of NaCl solution.
- As the wet curing was increased then so was the durability performance in these tests; however, there was a little improvement after 7 days of wet curing with these materials and in this testing. This finding should be investigated with a wider range of materials before changes in practice are made.
