Engeco Srl in the sewers and waterways sector
Intervention and structural consolidation of medium and large conduits in masonry and / or concrete. Engeco Srl maintains and rehabilitates pipelines for sewage networks in the historical centres of cities.
Engeco's work guarantees a total restoration of the functionality or static rehabilitation of the pipelines. Engeco aims to keep flow unchanged, maintaining the useful waste discharge.
In most cases when Engeco Srl intervene, sewers and waterways are already in operation. During the execution of the consolidation works, it is necessary to provide for the temporary deviation of the waste water in other ducts of the network, through the formation of sandbags or in conditions of particular water flow with in masonry. If this operation is not possible, a by-pass will be formed, consisting of a temporary pipe of PVC pipes, served by one or more electro-pumps, placed upstream of the project. In any case, the completion of these operations will enable the following interventions to be carried out in "dry" conditions.
HIGH PRESSURE HYDRO SCARIFICATION
The operation has a twofold function: first of all it is necessary for Engeco Srl to remove all the incoherent parts of the conduit and also serves to guarantee the formation of the necessary roughness of the surfaces that will then receive the new coating. Hydro-scarification will be performed with high-pressure water jet (up to 2,000 bar, 20 l / min) and for variable thicknesses depending on the conduit conditions and the project intervention.
This process is obviously carried out only in concrete ducts and in the presence of particularly degraded conditions, such that the execution of the hydro-scarification reveals the reinforcing rods of the manufactured article. In this case we will proceed to the anti-corrosive anti-corrosive protection of reinforcing rods, with the application of passivizing grout based on cements, selected aggregates, resins and additives, with products like Mapefer 1K or similar. Subsequently, the concrete cover will be reconstructed with controlled shrinkage mortar based on high-strength cements, selected aggregates, additives and fibers, with products such as Mapegrout FMR or similar.
One of the most common phenomena of deterioration of the manifolds is the formation of deep longitudinal lesions, mainly due to the failure of the piers, or transversal, often present in correspondence of the casting. The presence of these cracks further complicates the collector's situation, becoming an easy vehicle for further infiltration. Engeco Srl proceed with the rehabilitation of the lesions with the preventive enlargement of the cracks with manual or mechanical means, the careful cleaning of the created space and the blowing with water and compressed air for the removal of all the removed material, the injection with water slurry. and controlled shrinkage cement (such as Stabilcem or similar) using PVC canes, inserted into specially designed holes and the final sealing of the wound by means of a multi-component special mortar with synthetic resins and reactive inorganic compounds, with products like Duroglass sub or similar .
RECONSTRUCTION OF PIEDRITTI
The deterioration of the piers is mainly at the base, a part more subject to the erosive action of the waters. Over time, real digging can occur, with a consequent reduction in the static functionality of the piers. Engeco Srl proceed with the reconstruction of the missing or damaged parts of the building by means of full brick under pinning and saturation of the hollows behind by injections with water sludges and cement with controlled shrinkage (such as Stabilcem or similar) by means of PVC pipes inserted in specially designed holes; these operations will be carried out after the appropriate manual demolition of the parts of the structure that are no longer suitable.
If the previously mentioned erosive processes are particularly intense or prolonged in time, two types of phenomena can occur, such as to seriously undermine the integrity of the conduit. On the one hand, there will be a progressive loss of consistency of the piedritto which, especially if in concrete, will gradually lose its cement binder to the point of evidence of gyration phenomena. On the other hand, if the action of the water comes to completely erode the pierced in its section up to the ground behind, we will witness the progressive "suckling" of the lands, until the formation of overlapping that, with time, will affect even the integrity of the roadway above, with a considerable risk of settlements.
The function of consolidation injections is therefore twofold: to restore the static functionality of the piers, returning to concrete the cementitious part lost over time and consolidating the surrounding land, with similar aims to the jet-grouting works, up to the saturation of the empty areas, giving them a consistency comparable to the cement mixture. The injections will be carried out by inserting galvanized steel injectors into suitable holes, and the subsequent injection with anti-shrinkage rheoplastic cement grouts, with products such as Stabilcem or similar.
FIBRE REINFORCED STRUCTURAL PLASTER
The completion of the restoration cycle takes place through the formation of a thixotropic, shrinkage-compensated, sulfate-resistant structural plaster coating having the following characteristics:
- Fiber-reinforced with chrome-plated, amorphous (non-crystalline), corrosion-resistant, flexible and corrosion-resistant metal alloys, in a quantity> 0.9% by weight on dry mortar, with an aspect ratio l / d (length / diameter) apparent) of 125 (length equal to 30 mm, width of 1,6 mm, thickness 0,029 mm), having a specific surface of at least 8 m2 / kg, tensile strength> 1900 MPa and elastic modulus> 135000 MPa.
- Expansive capacities both in the setting phase (UNI 8996) and in the first setting phase. In the contrasted test of expansion, according to UNI 8147, the mortar will have to produce a contrasted expansion to 1 day equal to at least 0.04%. 90% of the final mixed expansion will have to develop within 36 hours of the dough packaging.
- Minimum compressive strength of 25 MPa at 1 day and of 63 MPa at 28 days according to UNI EN 196/1.
- Minimum flexural strength of 8 MPa at 1 day and 11 MPa at 28 days according to UNI EN 196/1.
- Static elastic modulus of at least 23,000 MPa at 28 days of maturing according to UNI 6556.
- Adherence to concrete not less than 4 MPa at 28 days.
- High resistance to sulfates, such as to ensure no degradation after 15 immersion cycles in MgSO4 according to the methods reported in the ASTM C-88 standard.
Depending on the state of conservation of the duct, the thickness of the material removed from the water-repellent and the design needs, it is possible to perform interventions for thicknesses from 1.5 to 12/15 cm. In the case of thicknesses over 3 cm it will be advisable to provide a reinforcement with one or more sheets of electrode-welded steel mesh, fixed to the existing piece by means of FeB44k iron pins.
SAFETY AND RISK PREVENTION
Given the particular work environment, particular attention will be paid by Engeco Srl to the prevention of injuries, adopting the measures listed below:
- During access to the conduit: verification of the stability of any steps present and / or use of telescopic ladders for the descent and ascent along the towers; verification of the presence of possible concentrations of harmful and / or inflammable gas, by means of a specific detector.
- During the work phases: simultaneous opening of at least three access manholes and use of a special system to guarantee the necessary ventilation inside the duct; use of lighting system and other electrical equipment powered by low voltage, use of winch for handling machinery and materials and possible recovery of injured parties.
- Personal equipment for the workers: boots, protective suit, gloves, respiratory protection mask, helmet with lamp, rope and harnesses.
- General equipment for the building site: first aid kit, self-contained breathing apparatus.
These measures will be integrated into the implementation of an operational plan for safety and emergency and emergency, specifically designed for work to be carried out in conduits and / or sewage channels, even of small size.