7.3.2 Surface hardness and P-wave Velocity variations
The surface hardness (Fig. 16) and P-wave velocity (Fig. 17) decrease
with increasing periods across all experiments. With an increasing
number of periods, the surface hardness and P-wave velocity of samples
gradually decrease, whereas the surface hardness decreases faster than
the P-wave velocity implying that the deteriorations of samples start
from the surface by water and transfer to the inner little. The surface
hardness and P-wave velocity decreasing rate are the highest when the
samples are immersed in pH=2.6; the lowest in the dry group; ranked in
the middle in the dry-wet cycle and saturated group. The surface
hardness and P-wave velocity deterioration of LA samples are greater
than that of LB samples when other conditions remain the same.