ABSTRACT
The left hand section of Figure 4 Shows results of preliminary measurements on the two columns to establish the range of p~ or RH to be expected. p~ in the control column was very high (more than 5000 kPa) and the measurements eventually went out of range. p~ in the silicone-treated column, however, was unexpectedly low (2000 kPa) and after a spell of heavy rain, reduced even further. A few days later streaks of white ASR gel appeared through cracks in the column and ran down the surface. This showed that water was entering the column via the structure it supports and causing further ASR. The silicone treatment was quite ineffective as the water was not entering through the surface of the column. In a second series of tests conducted during very hot dry weather, initial p~ readings were taken and the columns were then watered continually by hose over a period of six hours on three consecutive days to represent as severe a condition of wetting as is ever likely to occur on an outside structure.
