Effects of substituting D2O for H2O on SANS measurements of hydrating cement

Full text: Small angle neutron scattering (SANS) measurements of cement have been found useful in the investigation of the shape and growth of particles formed during hydration. Calorimetric measurements of hydrating cement samples have shown that the substitution of D2O for H2O has the effect of slowing the hydration process. In order to throw some light on this phenomenon, we have measured SANS profiles from cement samples hydrating in H2O and D2O. This involved obtaining SANS profiles at half-hourly intervals during the initial stage of hydration. The only instruments capable of this at present are located at the Hahn-Meitner Institute in Berlin and at the Nuclear Physics Institute at Rez near Prague. Initial experiments carried out on the V12a UltraSANS diffractometer at The Hahn-Meitner Institute were only partially successful owing to excessive multiple scattering in the D2O samples. Subsequent measurements were therefore carried out on the similar instrument at Rez near Prague which operates at a shorter neutron wavelength. Results from these measurements show profound differences in the evolution of cements hydrating in D2O and those hydrating in H2O