The stones in the wall surfaces of the bridge abutments had become disaggregated at many points and the binding agent between the blocks was nearly gone. The paving also showed a deep depression of about 6 cm.
Why the Uretek solution was chosen:
- Competitive prices;
- Non-invasive: The intervention proposed by Uretek did not alter the aesthetics of the masonry, and it did not dirty the area or produce waste;
- Monitoring of the work using laser technology;
- Uretek Walls Restoring® technology, specifically designed to consolidate deteriorated masonry using injections of expanding resin, which fills voids and joins elements in the structure. This guarantees uniform treatment at every point of the wall structure and is also effective in submerged masonry.
- Application of the IDRO CP 200 resin, produced exclusively for Uretek, has mechanical properties comparable to those of normal bedding mortars, is not subject to washout and is waterproof;
- Uniform treatment at every point of the wall structure;
- Respect for the environment Above-ground mixing of the Uretek® resin creates a final inert product that does not release solvents into the soil or possible water tables in the area.
We had two objectives: filling the voids present among the stone blocks, reuniting them, and restoring the flatness of the road paving.
To consolidate the wall surfaces, we chose the innovative Uretek Walls Restoring® technology, while we used the Uretek Floor Lift® technology for the road surface. In total, we treated about 200 m³ of masonry and 40 sq. m of paving in 9 days.
Before making the injections in the wall surfaces, we removed the deteriorated cement binding agent and stripped the joints, removing and cleaning the existing mortar to a depth of about 5 cm. At this point, we washed the surface of the masonry with water and chemical agents and then sealed and grouted the cracks and joints with new mortar.
THE PROJECT IN DETAIL
The instability in both the paving and masonry was due to two causes: prolonged washouts over time and heavy vehicle traffic on the road. How we worked:
Wall surfaces – Uretek Walls Restoring® technology
The two side wall surfaces of the abutment, situated along the road axis, each measured about 9 metres long and an average of 4.75 m in height.
The abutment, perpendicular to the road axis (supporting the bridge arch), was about 5.5 metres long, with a height of 9.5 metres.
To inject the special IDRO CP 200 expanding resin, we first drilled holes into the wall to cross through the discontinuities present within, then we inserted the injection tubes. The expansion of the resin, resulting from a chemical reaction causing an increase in volume up to about 2.5 times, allowed the mixture to reach communicating cavities or those close to the injection point. By extracting the tubes gradually, without interrupting the flow, the mixture spreads into all the cavities crossed, eliminating discontinuities which can represent dangerous structural weaknesses.
Walls Restoring® is also applicable to brick, stone, or mixed-material structures such as piers, wharfs, buttresses, containment walls, and foundations.
Walls Restoring® è applicabile anche a strutture costruite con mattoni, materiale lapideo o materiali misti come banchine, argini, contrafforti, muri di contenimento e fondazioni.
Road paving – Uretek Floor Lift® technology
The paving, installed in the 1970s, consisted of a reinforced concrete slab with a thickness of about 35 cm, topped by a layer of asphalt with a varying thickness. The subsidence, already noted in 2010, showed a sinking of about 3 cm (maximum 6 cm) at the time of the intervention. It is probable that water had been flowing under the slab, leading to washouts. In recent years, upstream drainage aimed to eliminate this problem.