ABSTRACT
In order to characterize this effect, we have performed experiments on paste samples made with pure CEM I cement and a mix of CEM I+ 30% of silica fume with the same water/binder ratio. Chemical attack and compressive tests are conducted on micro-cylinders samples (I 0 to 30 mm of diameter). The leaching of calcium is due to the attack of a 50% solution concentrate of ammonium nitrate. The removal of Ca ions is monitored by microprobe analysis which allows to plot the Calcium profile along the samples. The removal of Ca(OH)2 is monitored by the plot of XRD curves at different depths obtained by polish sequences. The results show that the peripheral degraded zone is delimited by the dissolution front of calcium hydroxide and that the leaching process leads to a progressive decalcification of CSH.
