Capillary water absorption and free shrinkage characterization for seawater sea-sand concrete

Abstract

The durability of seawater sea-sand concrete (SSC) and/or sea-sand concrete (SC) structures exposed to harsh marine environments is crucial to their service life. In this study, we investigated the capillary water absorption of SSC, SC, and ordinary concrete (OC) with different water–binder ratios (i.e., 0.38 and 0.28) in deionized water and composite saline solutions. The results showed that the cumulative water absorption of OC, SC, and SSC in the composite saline solution were lower than that in deionized water. In deionized water, the cumulative water absorption of OC is the largest, followed by those of SC and SSC. However, in composite saline solution, the cumulative water absorption of the three types of concrete with a low water–binder ratio at less than 6 h was similar; after that, SSC exhibited the highest absorption, followed by SC and OC. Moreover, the initial water absorption rate in deionized water was approximately four times higher than that in the composite saline solution. In contrast, for concrete with a low water–binder ratio, the secondary water absorption rate (after 6 h) was approximately two times lower in deionized water than in the composite saline solution. The free shrinkage of the three concrete types have been measured up to the age of 210 d. The results showed that under the same curing age, the shrinkage strain of OC was the largest, followed by those of SC and SSC. Based on the GL2000 model, a new prediction model for the shrinkage of SSC and/or SC was established by introducing an expansion effect coefficient. The proposed model could accurately predict the development of the shrinkage strain in OC, SC and SSC.