MICROSTRUCTURE OF LONG TERM MARINE IMMERGED ANTI-WASHOUT CONCRETE

In this contribution, the microstructure of long term marine immerged anti-washout concrete was investigated. In the experimental program, a new anti-washout agent was used as the control anti-washout concrete mixing. For other two mixtures, the content of cement was replaced by fly ash 30% and fly ash 25%+silica fume 5% (in mass), respectively. SEM observations were used in analyzing the damage of concrete immerged in sea water after 720 days. The results of Scanning Electronic Microscope (SEM) show that there are sonic crystals observed on the surface of the control concrete, where crystals grow thick and complete. A lot of AFt was observed inside the concrete. The Surface of concrete mixed with fly ash and silica fume was compact and the crystals were tiny. Only few AFt was observed inside the concrete. The composition of the crystal on the surface of the control concrete detected by Energy Dispersive X-ray Spectrometer Analysis (EDXA) was very complex. However, the composition of the crystal on the surface of concrete mixed with fly ash and silica fume was mostly Mg(OH)(2).