Some existing masonry structures exhibit structural issues but must be retained in place (party walls, parts of structures that are costly or complex to replace). When these issues involve cracks or deterioration of mortar joints, filling voids with grout can provide effective consolidation.
Solution
The use of an injection grout based on PROMPT natural cement by Vicat will enable the reinforcement of ancient masonry walls. This involves gravity or low-pressure injection of grout to fill voids within the wall. PROMPT natural cement, used as pure paste grout, grout/aggregate mix, or in combination with hydrated or hydraulic lime, will save time and material while also reducing hydrostatic pressure of the grout. With PROMPT natural cement, vapor permeability is also preserved.
Technique
Before initiating the injection of PROMPT natural cement grout, it's essential to prepare the substrate. Prior repointing of stones or the presence of renders capable of fulfilling this role is necessary. Next, dampen the substrate and create injection holes with a diameter of 10 to 20 mm, inclined downwards at a 45-degree angle through 2/3 of the wall's thickness, forming a triangular pattern every 50 cm. Depending on the state of the masonry, work in sections of 1 meter in height.
Subsequently, prepare the grout in a concrete mixer or electric mixer. To do this, possibly introduce half of the mixing water with TEMPO, then optionally add sand and/or lime.
Next, introduce the other half of the mixing water, followed by adding the PROMPT natural cement by Vicat.
A mixing time of less than 5 minutes is recommended. Then proceed to injection by filling a funnel attached to a flexible hose that will fill the previously created holes.
Injections of grout based on PROMPT natural cement into historic structures allow for :
- Repairing masonry structures with structural issues that must be preserved, achieved through filling voids and cracks
- Anchoring micro-piles drilled into masonry or the surrounding soil
- Sealing water ingress points and waterproofing floors, thereby avoiding the costly use of water-reactive resins
The addition of PROMPT natural cement by Vicat to a lime injection grout offers several advantages due to the quicker setting of the grout :
- Injection into zones at the edges of structures is facilitated by the rapid setting of the grout, reducing leaks and resulting in material cost savings
- Injections can be carried out from one day to the next, or even sooner, due to the shortened consolidation time before applying load. This helps avoid excessive hydrostatic pressure that could jeopardize the structure
- Reduced leakage due to the faster setting of the grout
- Ability to work in cold weather conditions
- Adjustment of the setting time for better control of the injection volume
- Permeability of the wall is maintained, similar to using hydraulic lime grout
- Suitable for reinforcement work at significant heights
