Passage I

Deicers (mixtures of salt and water that are used on roads to melt ice) can over time cause concrete pavement to deteriorate.

Two studies examined how 4 different deicers affected the length, mass, and compressive strength (CS) of identical cylinders made of hardened concrete. (CS is the maximum lengthwise pressure that can be applied to the ends of a cylinder without crushing it.) Each deicer was 15% by mass of , , , or kept at 4°C.

Study 1

Five of the cylinders were submerged in 4 L of the deicer. Every 25 days over the next 600 days, the following was done:

1. The 5 cylinders were removed from the deicer and wiped dry.

2. Each cylinder's length and mass were measured.

3. Two average values were calculated for the 5 cylinders: the average percent change in length relative to the original length and the average percent change in mass relative to the original mass.

4. The cylinders were resubmerged.

All of the above procedures were repeated for the other deicers (see Figures 1 and 2).

Study 2

Sixty more of the cylinders were submerged in 20 L of the deicer. Every 50 days over the next 600 days the following was done:

1. Five cylinders were removed from the deicer and wiped dry.

2. Each cylinder's CS, in megapascals (MPa), was determined.

3.The average CS was calculated for the 5 cylinders.

All of the above procedures were repeated for the other deicers. Finally, the CS of 5 more of the cylinders—cylinders that had not been submerged in any deicer—was determined, and their average CS was calculated (see Figure 3).