On the other hand, absence of latex particles in the capillaries
and voids as in the case of NC might have rendered the matrix vulnerable
to attack through ingress of the surrounding Na2SO4 ions.
Indeed, sulfates react with the hydrated aluminates in the cement
to give high-sulfate tricalcium sulphoaluminate or ettringite which
normally occupy more than twice the molecular volume of the aluminate
and its formation in hardened pastes is accompanied by
expansive forces which can exceed the tensile strength of the concrete
[27].