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In this paper, the influences of internal curing using pre-soaked lightweight aggregate (PSLWA) and pre-fabricated fiber reinforced engineered cementitious composite (ECC) board as permanent formwork on shrinkage and internal relative humidity of high strength concrete were investigated. Three mixture proportions with induced curing water-to-cement ratios (W IC /C) of 0, 0.08 and 0.12 were utilized in the experiments. The test results show that the progress of the internal relative humidity of high strength concrete since casting exhibits first a vapor saturated stage (RH=100%, stage I), followed by a gradually reducing stage (RH<100%, stage II). As PSLWA is added, the reduction rate of internal relative humidity in stage II is greatly decreased. As ECC cover is used, the reduction on internal humidity of high strength concrete is further reduced. Shrinkage of high strength concrete decreases with increase of induced internal curing water. However, internal curing cannot completely eliminate the shrinkage of high strength concrete developed in the stage I. The combined effects of internal curing and ECC cover can reduce the shrinkage not only developed in the stage II, but also the shrinkage developed in stage I.

The brittleness and easiness to crack expose marine concrete to serious durability issues. Engineered Cementitious Composites (ECC), as a new generation of ultra high performance concrete, is expected to overcome the strain-softening properties of traditional concrete and realize function of crack-width control. In this paper, the sulfate erosion of ECC under drying-wetting cycles was modelled in laboratory test. And the compression test on cylinders after exposure to different erosion cycles was implemented to obtain the stress-strain properties. The results disclose that sulfate erosion imposes significant influence on both the nonlinear ascending and descending portions of the stress-strain properties of ECC. As the erosion period extended, ECC strength undergoes an obvious increase. And the descending section of the eroded ECC shows a significant stress drop, which is quite different from that before erosion. Additionally, a simple analytical model was proposed to provide satisfactory prediction of the stress-strain properties of ECC exposed to sulfate erosion.