Environmental Engineering Reference
In-Depth Information
Figure 8.12.
Bullet impact on a small limestone building, Baalbek, Lebanon
Stones with low compressive strength and correlatively high porosity are less
durable. Tuffeau stone (6 MPa, with 50% porosity) is one of these, yet some
Tuffeaux stones are more durable than others, depending on the quarry they
originate from. To understand the reason for such differences, Dessandier [DES 93]
has measured a number of parameters on a set of Tuffeaux, and established for this
stone a theoretical durability factor (FDT) that varies as a function of four
parameters: compressive strength in dry and wet states, porosity and saturation
coefficient.
(
)
FDT
=
1.59 R dry
+
R wet
+
1.12N
−
2.28S
+
131.2
[8.1]
c
c
t
48
with:
R
c
dry = compressive strength, dry state (MPa);
R
c
wet = compressive strength, wet state (MPa);
N
t
= total porosity;
S
48
= saturation coefficient (100 x porosity freely accessible to water after
48 hours N
48
, divided by porosity accessible to water under vacuum, N
t
).