CONSTRUCTION SITE: SCANDICCI (FI)

PROBLEM: REPAIR OF AN EXPANSION JOINT WHICH FEATURED WATER LEAKS

SOLUTIONSOLUTION
Case History Our technician carefully evaluated the problem on site, and discovered that there was a seriously damaged expansion joint from where pressurised water was leaking. Considering this type of repair is a delicate task because the expansion joint has to be repaired but it also has to maintain its capacity to “absorb” the expansion and retraction of the concrete (movement caused by the changing thermo-hygrometric conditions), the following procedures were advised:
Case History
- using a diamond disk, cut the joint to the right and left, thus forming a reverse, dovetail notch. Distance between centres between the two cuts: approx 2-3 cm; depth approx. 9-10 cm.
- Demolish the concrete between the two cuts and smooth the bottom of the notch. Roughen the walls of the notch using a wire brush.
- Apply about 2-3 cm of instant mortar (KEYPLUG type) on the bottom of the notch to stop the flow of water during the repair.
- Clean and dry the notch
- Spread the SYNKO-FLEX PRIMER on the bottom of the notch and on the side walls and leave to dry.
- Lay the RAM-NEK or SYNKO-FLEX type waterstop by peeling the transparent paper and heating the latter with a hot air torch to ensure its entire section completely adheres to the primer.
- Seal the notch with the waterstop up to 1 cm thickness above the upper edge of the slab.
- Peel the brown paper from the waterstop and close the notch with sheet metal fixed to the slab by two expansion screws.

CONSTRUCTION SITE: VICENZA

PROBLEM: RESTORATION AND PROTECTIVE TREATMENT OF AGGRESSIVE SEWAGE COLLECTION TANKS USING AN EPOXY-BASED SYSTEM OFFERING HIGH RESISTANCE TO CHEMICAL AGENTS.

SOLUTIONSOLUTION
Case History From the inspection carried out on site, it emerged that the tanks had been treated with epoxy resins and reinforced with polypropylene fibre mesh during construction; the epoxy protection on the tanks proved to be slightly damaged but most of the surface was still sound. In some points, the protection had collapsed and the underlying concrete was corroded to a depth of a number of centimetres, and the mechanical resistance of the exposed concrete appeared to be reduced. The following was advised:
Case History- Identify the areas to repair and demolish the damaged concrete, leaving just the sound concrete which retained its mechanical resistance
- Remove and dispose of waste material.
- Reintegrate the demolished concrete with REPOBIT type epoxy mortar, to restore the original surface.
- Sandpaper the entire tank surface and apply the first coating of REAT type epoxy-based primer in the ratio of g/m2 300
- Skive an approx. 3 mm thickness of epoxy mortar.
- Reinforce with a polypropylene fibre mesh
- Apply a final coating of RECRE type epoxy system in the ratio of g/m2 1000

CONSTRUCTION SITE: NOGARA (VR)

PROBLEM: SEAL OF LARGE PREFABRICATED ELEMENTS FOR SEWER CONSTRUCTION

SOLUTIONSOLUTION
Case History After an initial meeting with the person in charge of the construction site and the supplier of the elements, the following indications were provided:
- Install the first element in its working position in the excavation
- Clean the area where the RAM-NEK type waterstop was to be applied (using a wire brush and a dry rag), so that the element is free of moulds, dust, inconsistencies and/or foreign bodies.
- Apply the SYNKO-FLEX PRIMER in the male/female area where the waterstop is to be applied and ensure it is perfectly dry before applying the latter.
Case HistoryCase History - After peeling off the transparent paper, the waterstop was heated with a hot air torch because the temperature was particularly rigid
- The waterstop was placed in position (the brown paper was left on) ensuring that the entire section of the waterstop adhered to the element and the strips were overlapped by at least 5 cm to ensure continuity. The RAM-NEK was positioned on the upper part and the sides of the structure (on the male element) and on the lower part (of the female element) to ensure it was positioned as much as possible on the structure and not just hanging off it.
- Approach and align the second element with the first, after peeling off the brown paper on the waterstop.
- Push the second element into its working position.
- In some cases, considering there were excessive tolerances between male and female elements, it was necessary to apply a dual strip of RAM-NEK.

CONSTRUCTION SITE: AREZZO

PROBLEM: PRODUCTION OF LIGHTWEIGHT AERATED CONCRETE AT TEMPERATURES BELOW 5° C FOR THE CREATION OF A THERMAL INSULATING SCREED

SOLUTIONSOLUTION
Case History After an initial meeting with the customer, who complained about the unsatisfactory results achieved during the production of lightweight aerated concrete made in cold temperatures, our technician advised the following
- Start the pour only when the temperature was above 0° C and ensure there is no ice on the surface where the lightweight aerated concrete was to be applied
- Stop the pour at least 3 hours before the temperature drops to 0° C.
Case History - Use Portland 425 type cement, stored in a protected and covered area and AGON C or FOAMIN C type foaming additives, diluted in water in the ratio of 1 or 2 respectively.
- Carry out a foam production cycle using an aerator and ensure that its weight is 60-65 g/litre for AGON C and 70-75 g/litre for FOAMIN C.
- Increase by 5-7 the quantity of cement provided for the required density (which was 400 kg/m3). In other words, instead of using 330 kg/m3 of cement (the normal recommended quantity), use 340-350 kg/m3.
- Use the least possible quantity of water to mix the cement/water, use an antifreeze such as calcium chloride (cooking salt) refined to the utmost and add to the cement mixing water (quantity: from 1 to 3 kg per ton of cement)
- Do not pour if the temperature settles below 0°.
The importance of carrying our correct maintenance on the machinery was also pointed out.
- Cover electrical parts on machinery left outside in the open air using impermeable sheets. Also protect any control panels and place at a distance from any machinery and above ground.
- Every time work is interrupted, remove any cement deposits inside the mixer and pump by washing with water, before the cement hardens.
- Empty the aerator tank using the nozzle and wash with a jet of pressurised water
– Do not use any diluted additive left inside the aerator the day after production.

      

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