『Abstract
A common decay scenario in old and new buildings was simulated:
the effects on masonry structures of salt efflorescence or subefflorescence
produced by the rise of saline solution. Eight different types
of masonry wall each made up of a combination of different construction
materials (brick, calcarenite and four types of mortar were combined
as follows: pure lime mortar, mortar + air entraining agent, mortar
+ pozzolana, mortar + air entraining agent + pozzolana) have been
tested. These materials have different textures (strong anisotropy
in brick, irregular-shaped pores in calcarenite, retraction fissures
or rounded pores in mortars which also show a reduction of porosity
along the contact area with the stone), different hydric behaviours
(under total immersion brick + mortar specimens absorb water faster
than calcarenite + mortar specimens) and different pore size distribution
(brick shows unimodal pore distribution, whereas calcarenite and
mortars are bimodal). In the salt weathering test, mortars interlayered
with masonry blocks did not act as sacrificial layers. In fact,
they allowed salts to rise through them and crystallize on the
brick or calcarenite pieces causing the masonry structure to decay.
Only the addition of an air-entraining agent partially hindered
the capillary rise of the salt-laden solutions.
Keywords: Masonry walls; Efflorescence and subefflorescence; Porosity;
Weathering』
Introduction
Materials
Methods
Results and discussions
Optical microscopy
Brick and calcarenite
Mortars
Hydric tests
FESEM observations
Salt crystallization test
Changes in masonry texture after simulated weathering test
Conclusion
Acknowledgments
References