The Spanish Walls of Milan


The use of instrument grouting system has been in place for years, both in Italy and abroad, in many yards, giving an important aid in the joints of the masonry brick of natural stone. The analysis of the use and usefulness of the instrument was verified on a very large and important shipyard, having as object the improvement of the Spanish Walls of Milan (figure 1), with thousands of metres of mortar joints (figure 2).
The joint system was designed to facilitate and speed up the long process of sealing of joints (figures 3-4-5) that lie between the bricks or stones and that, over the years, have lost much of the bedding mortar which constituted the link between the rows of stacked bricks.
These gaps should be restored to prevent further degradation leads to a possible collapse of the walls.
Until now the joints were restored by manually inserting the mortars, creating problems precisely from the system by which the operator inserted the new mortar into the joint itself using a small spatula: the joints have a size of about one centimeter and pushing the same mortar from outside to inside, it was not certain that it had completely filled the joint.
using the grouting machinery, this does not happen because its nozzle allows it to enter the joint and fill it from inside to outside.
Another problem in the manual joining was the cleaning of the bricks or stones from the grouting mortar because, with a small spatula and a liquid mortar, inevitably the mortar was dripping and getting dirty.
The mortar system is equipped with pipes that allow it to work up to 5 m high without moving the machine.

If it is necessary to move the machine, it is equipped with a structure with wheels and handles that facilitate handling.
The instrument is also equipped with a remote control that the operator will easily hold with his left hand, as with the right he will have to hold the injection nozzle, which allows him to start and stop the machine, electronically adjust the speed of the machine, which can vary from 0 to 180 l/h, and to use the counter-pumping device, which allows suction of excessive groove mortar that could spill from the nozzle.
In the top part, the machinery has a 9 liter conical hopper in which the grouting mortar is supplied, which can also have a 3 to 4 mm granulometry.
The 12 Vdc motor, which moves the peristaltic pump, can be powered by batteries, with a battery charger, or 230 V electricity.
By replacing the flat nozzle with the round bushing, the machine can be used as an injector pump (figure 6).
There is also a version for microinjection (figures 7-8), with micrometric flow regulation, equipped with a needle nozzle and pressure gauge for pressure control. Of course the mortars will have to be much more fluid and have a proper granulometry.

[by Vittorio Bresciani]