Environmental Engineering Reference
In-Depth Information
Analysis included hygroscopic dilatation, water uptake coefficient, water vapor
diffusion resistance coefficient, micro-drop adsorption, and the contact angle.
Abrasion resistance was measured according to the compressed earth block testing
procedure [SER 00].
Penetration measurement and the softening point of the bitumen were
determined by the LCPC (Laboratoire Central des Ponts et Chaussées in Paris).
Samples were taken of the decorated surfaces next to already existing cracks.
The painting techniques are still being used and allowed for comparison with
analytical results. Cross-sections were used for optic and scanning electronic
microscopy (SEM) analysis. Sections were gold coated for the SEM study. The
identification of materials was done through EDX-analysis, X-ray diffraction and
chromatography analysis.
11.2.3.
Results
11.2.3.1.
The bitumen plaster
11.2.3.1.1. Physicomechanical properties
The efficiency and compatibility of the bitumen plaster with the adobe support
was analyzed. The study revealed that characteristics of the bitumen plaster were a
function of the bitumen content.
Resistance to abrasion is obviously linked to the bitumen content. A plaster made
with 2% bitumen presents an abrasion coefficient of 3.4, while a plaster with 5%
bitumen has an increased coefficient of 9.2. The adobe support coefficient is 1.5.
The plaster demonstrates efficient protection of the building. The hydrophobic
characteristic of such plaster is of the greatest interest, however, in relation to the
intense rains in June.
Surfaces covered with a 3% bitumen plaster are already totally hydrophobic (see
Figure 11.18).
Indeed, a hydrophobic surface should present a water uptake coefficient inferior
or equal to 0.1 kg/m
2
.√h [SAS 96]. A 3% content verifies this property since a 2%
content reveals a coefficient upper than W = 0.2 kg/m
2
.√h.
