or less particle size obtained from j m huber corporation one huber road macon ga u s a 21298 the early compressive strengths of mixes nos 8 and 22 show a consistent and substantial increase over either of mixes nos 10 or 12 mix no 7 also contained 5 kaolin but did not exhibit substantial strength increases probably due to insufficient water for hydration 13 as compared to 23 for mixes 8 and 22 however mix no 7 which had insufficient water showed a substantial improvement in early strength over that of mix no 10 the following were prepared using the astm c 109 cube procedure for the purpose of comparing cubes for compressive strength analysis utilizing a given or known mixture representative of an actual concrete mix with the water content determined by the flow table these are set forth in the following table 2 for mixes 33 34 and 36 table 2a______________________________________material mix 33 mix 34 mix 36______________________________________fly ash 100 g 148 g cement 500 g 400 g 400 g sand 1 375 g 1 281 g 1 375 g alumina clay 94 g water 230 g 288 g 239 g flow 108 110 108______________________________________ table 2b______________________________________compressive strength psi pounds per square inch material mix 33 mix 34 mix 36______________________________________1 day 1 317 1 325 4653 days 2 500 2 062 7 days 2 980 2 910 ______________________________________ mixture 34 confirms that a normal 20 replacement of cement with fly ash plus about 5 alumina clay equates to a straight portland cement mixture with no replacement of the cement in terms of early strength mix 36 demonstrates a substantial reduction of strength at 1.