Waterproofing of old industrial building walls

Descripción sistema

Industrial building located in the Poblenou neighbourhood of Barcelona, known for many years as the “workshop of Barcelona”, or the “Catalan Manchester” due to its industrial character and the large number of factories it housed.

Industrialisation in this area, as well as in other sectors of Barcelona, led to the construction of wells for intensive groundwater abstraction from the beginning of the last century until the 1970s, from the coastal area and from the Llobregat and Besós aquifers.

As a result of the extraction of water, there was a sharp drop in the water table, which reached its maximum in 1975, reaching more than 10 m below sea level in some areas of the Llobregat.

The cessation of industrial activity led to the closure of the wells and the cessation of extraction, which caused the water table to rise to its initial levels, resulting in the flooding of basements that were built on dry ground, damage to structures and the flooding of some sections of the underground.

In the particular case of this industrial building, the effect is in the form of a strong capillary rise in its masonry walls, which must first be resolved in order to be able to apply a new coating mortar on them.

Reason for the intervention

Resolve the entry of humidity by capillary rising inside the building, and apply a new coating mortar on the walls. A favourable climatic condition, such as the summer season, should be taken advantage of to carry out the work.

Characteristics of existing support

The walls constitute a heterogeneous support in which stone and different types of brick are combined, joined together by a mortar of medium mechanical resistance.

Challenges and constraints

“Difficulty in defining the chemical barrier at the base of the wall, due to the lack of linearity in the mortar joints.
“Need to improve the resistant characteristics of the mortar joints and the surface of the substrate to prevent the appearance of cracks in the new render.
“As it is a closed room, it is necessary to ventilate to favour the drying of the plaster and avoid condensation.

Molins Solution

In view of the conditions described above, the operation proposed by Molins consisted of the following:
“Cleaning the current support of the remains of old plaster.
“Create a chemical barrier at the base of the wall.
“Apply a mineralising and consolidating liquid to the surface of the substrate.
“Apply a waterproofing mortar up to a height of 2.5m.
“Apply a water-repellent rendering mortar reinforced with fibreglass mesh as a new coating.

Execution

Preparation of the substrate
This first stage of the work, which is of great importance, consisted of removing the remains of old plaster and loose particles from the surface of the substrate.

Chemical barrier
Generically, in the case of stone walls, the water-repellent barrier for the treatment of rising damp is defined by a continuous line of holes, coinciding with the course of the stone joints:

In accordance with this procedure, the product PROPAM® CREAM, a cream based on siloxanes in aqueous dispersion, was used by injecting it into holes with a maximum spacing of 10 to 12 cm between them. The depth given to each hole is the width of the wall minus a safety buffer of 2 to 4 cm.

Surface consolidation
Prior to the application of the waterproofing mortar, the surface of the substrate was mineralised and consolidated with the liquid product PROPAM® MINERALIZADOR, with great penetration power, which has allowed a uniform resistant behaviour and an immediate reduction of capillarity to be obtained on the surface.

Waterproofing mortar
After 24 hours, PROPAM® IMPE (mortar formulated with cement, selected aggregates and waterproofing resins) was applied by spraying machine, filling all the existing holes in the substrate and obtaining a continuous coating of about 3-4 mm thick, completely waterproof.

Coating mortar
Once PROPAM® IMPE was dry, the waterproof rendering mortar PROPAM® REVOC reinforced with REVAT® 110 fibreglass mesh was applied. The application of a bonding bridge was not necessary, as the surface irregularity of the substrate itself and the roughness created in the PROPAM® IMPE waterproofing mortar during the application process were considered sufficient for the mechanical adherence of this mortar.

Before and after

Source

VENTAYOL, A. (1998): “Análisis del Ascenso del Nivel Freático en Barcelona”. Correo de la Construcción. Barcelona.