The Crack of Harden Cement Paste Observed with Multi-technique

The shrinkage of the cement paste with low water-cement ratio at different relative humidity was observed and analyzed with ESEM and deformation map technique.The crack morphology was observed with different magnification with SEM and FESEM,and the formation of the crack was observed with AFM between two C-S-H nano particles.The observation by multi technique at multi scale indicated that the shrinkage was increase with the decrease of the humidity due to the increase of the pressure of the capillary pressure,the morphology of the crack in smaller scale was similar to that in the bigger scale,the smaller crack distributed in the latticework of the bigger ones,and the crack propagated along the gap between two nano particles of C-S-H with weaker bonding.