ABSTRACT
In the field, pfa and natural pozzolans have not always proved effective in preventing cracking and expansion due to ASR. Examples are:-
(i) A test road constructed at McPherson, Kansas [2]. In this road 25% of the cement was replaced by one or other of three mineral admixtures - two natural pozzolans and a fly ash. It was found that the three pozzolans increased the number and width of the transverse cracks. Increased expansion from the use of fly ash has more recently been reported in Nebraska, Missouri, Icwa and Indiana [3]. (ii) The Hanshin Expressway in Japan. A proportion of the piers supporting this expressway, which cracked as a consequence of ASR, contain about 20% fly ash by mass of cement[4].
