Concrete repairs, crack sealing Part 11b)-2 Concrete repairs, crack sealing and waterproofing using 1-component PU resins (Part 11b, PP 2007, animation+p/r, compr. : 2009.03.31, rev. 2016.06.04) Copyright notice Unauthorised copying of this presentation as whole or in parts in any form or by any means, electronic, photocopying, recording or otherwise, without prior written permision is prohibited. ready

Mechanical packers with HP-pan-head nipple – cont. HIGH PRESSURE HOSE BETWEEN THE MIXING UNIT AND THE PACKER SLIDING COUPLER BETWEEN HIGH PRESSURE HOSE AND THE PACKER Packer for Injection with HP-pan-head nipple (Ø 10÷16 mm) Fine cracks Ø10 mm, L = 155 mm (not recommended by the author) Fine to Medium Cracks Ø13 mm, L = 110 mm Medium to large cracks Ø16 mm, L = 110 mm For medium large to very large cracks without pan-head nipple Ø 16 mm, L = 125 mm Ø 20 mm, L = 125 mm Author recommendations: finer crack → larger diameter of packer !! HP-Pan-Head Nipple Ø 16 mm press ready press

Flushing of the joint It is advised to flush the crack with water before injection with PU resin. This will flush out dust, debris and prime the crack for the injection resin and improve penetration of the product into the crack. Water in the crack will activate PU resin, but normally the concrete close to the crack is saturated by flushing water. Otherwise a concrete humidity of 6% is enough to ensure a proper reaction. The flushing may also reveal hidden cracks and help to understand how the crack spreads, develops and will behave under injection. Blind holes can be eliminated and cavities or honeycombs can be marked for special attention. press ready press

Flushing should be started at the lowest point of the crack or the narrowest part of a horizontal crack. When proceeding from one packer to the next, the water shall escape from the crack. If flush water will not flow into the packer the hole is probably blind. The packer must be removed and the hole closed up with fast setting cement. A wide crack will allow more volume at a lower pressure than a narrow crack, but always the volume and pressure levels should be increasing slowly. The crack should be flushed with the highest possible flow volume practical bearing in mind not to exceed the pressure limits allowed by the age, thickness and condition of the concrete. Always is recommended using a separate pump for flushing with water. If this is not practical the pump must be sufficiently flushed with the cleaning agent like CarboSolv D in the case of Minova CarboTech grouting system. The reason is to dry the pump and prevent resin from reacting inside the pump. press press ready press

Flushing of the early-age thermal cracks Drilling Vacuum suction of drill powder (borings) Installing of packers Water flushing using separate hand pump Flushing of the early-age thermal cracks with water through the packers ready

Drilling method – not recommended Flushing of the early-age thermal cracks with water through the packers Grouting using PUR Flushing of the early-age thermal cracks with water through the packers – cont. ready

Resin preparation The resin has to be prepared with the predetermined quantity of catalyst. The reaction speed must be adjusted according to the mixing diagrams of Technical Data Sheet from the Producer to make adequate reaction times sufficient to fill the hole with resin, and thus not for pushing already reacted foam. No reaction with PU resin will occur until the resin comes into contact with water. The resin must be protected from water, since this will trigger a reaction in the vessel used and might cause the resin to harden or foam prematurely within the injection equipment. press ready

To compare: heavy grouting equipment for cement slurry Recommended membrane pump for 1-comp. PU resins Simple pump for 1-comp. PUR resins driven by boring machine – not recommended Simple hand pump for 1-comp. PUR resins and epoxy, useful for water flushing through the packers ready

Simple hand pump for water flushing through the packers ready Simple hand pump for water flushing through the packers and membrane pump for 1-comp. PU resins

ready Grouting pump for 1-comp. PUR and (acrylic resins) driven by drill machine – not recommended

higher grout output than 2÷3 litres/min. To avoid concrete fracturing during grouting in fine fissures should not be used: piston pumps, higher grout output than 2÷3 litres/min. Packer and nippels: - for PUR, - for epoxy resins, - for cement slurry. press press ready Not recommended Recommended Selection of the injection tools – cont.

Preparation of the injection equipment It is highly recommended to use separate pumps for water and PU resin injection to prevent contamination and blockages as mentioned above. The pumps must be thoroughly primed with the cleaning agent like CarboSolv D and CarboSolv S to lubricate and dry the system before starting injection. The thumb rule is that the viscosity of a resin changes with its temperature: - Warmer temperature = lower viscosity. Colder temperature = higher viscosity. In cold working conditions or very cold leaking water the resin will be more difficult to flow in the pump and the crack. Therefore pre-heating the resin > +20 °C is suggested. press ready press

Injection The Contractor always has to consult the Technical Data Sheets and Material Safety Data Sheets prior to its use. The pump will be filled with resin first and charge the hose and gun. It is absolutely vital to keep the resin supply covered from dripping water. Depending of the situation it is indicated to remove all trapped air in the pump and hoses. Sequential procedure to remove the trapped air is the following: - Pumping with loose high pressure hoses first until the air escapes and the resin starts flowing. - Tightening the high pressure hose and pump. - Tightening the ball valve and the packer connector. Connecting the spherical valve, continuation primes the system, closing the valve when the resin appears. Connecting the packer head. The injection will always start at the first packer (i.e. the lowest packer in a vertical crack or the packer at the narrowest end of a vertical crack). Grouting should start at the lowest pressure setting of the pump. press press ready press

… now start grouting this hole The general sequence of PUR grouting continue this hole … The general sequence of PUR grouting press press ready

Drilling and PUR (1-comp Drilling and PUR (1-comp.) injection – sealing of cracks in bottom slab ready

between high pressure hose PUR grouting with sliding coupler between high pressure hose and the packer PUR grouting using “grouting gun” press ready

If the resin does not flow through the line into the crack, the pump pressure at the pump will slowly be increased until the resin shows good regular flow. Pressures may vary between 30 bars to 150 bars depending on the size of the crack, thickness of the concrete and general condition of the concrete. The thumb rule is to allow enough time for the resin to intrude deeply in the structure. When the resin starts to flow, water will be observed flowing out of the crack first. Grouting will be continued until resin starts to flow from the crack. Then grouting should be interrupted for a few minutes to allow the initial reaction of the resin with the water and then inject again. The pressure must be maintained so that the resin can react under pressure. Large spills of resin should be stopped by filling up the crack with wet cotton rags or cotton rags with resin. It is recommended to wait for the resin to cure, and then pump again to fill up the crack and densify the foam gasket. It is recommended wetting the wall/floor etc. with water and maintaining it wet before the grouting to allow easy removal of the PU foam after curing. press ready press

This will seal the injection port and further densify the crack. A little leakage of resin through the concrete or crack is useful in showing the extent of resin travel. During the injection under normal circumstances first water will flow from the crack, followed by foaming PU resin. After this, pure resin will flow from the crack. The pumping will be stopped when the pure resin reaches at least the next packer + half a distance to second next, the packer is not sitting in the hole properly or the refusal pressure is reached. After injecting a few packers, it is recommended to go back to the first one and re-inject with PU resin. This will seal the injection port and further densify the crack. press ready

The water bearing crack before and after PUR grouting ready press The general sequence of PUR grouting – cont.

The water bearing crack after PUR grouting filled with PUR line of packers press ready The water bearing crack after PUR grouting

Re-injecting with water After the resin injection, small amount water can be re-injected into the ports to cure resin left behind. Caution Semi-reacted resin in the packer may react under very high pressure when the packer is opened / removed. However this may not show. Try to post-inject with water before removal. Always wear face shield and protective clothing, and stand sideways of the packers when you remove them. Removing packers The safety precaution is to let the resin cure thoroughly, before removing the packers. Packers can be removed by cutting flush with the concrete surface or by untying with spanner or wrench. The resulting holes can be filled with hydraulic cement and the surface treated as wanted. Excess resin on the surface can be removed by wire brush, scraper or hand held grinder. Accidental spills over dry substrates are difficult to remove and stains may be visible afterwards. Once used packers must never be used again! press ready press

Drilling and PUR grouting in the case of difficult access ready

Concrete fracturing (spalling) during grouting with PUR Mistakes: Piston pump instead to membrane pump. To high pumping rate. To short reaction time. To large foaming rate. Packer to close to the surface. Concrete fracturing (spalling) during grouting with PUR of crack in the concrete wall press ready press

Concrete repair of a crack in concrete tunnel lining – with surface treatment (not recommended) Grouting pump operator blind! Adhesive for plugging of crack before injection press ready Concrete repair of a crack in concrete tunnel lining – without surface treatment

press ready Caution Injected PU resin in the packer, even after re-injection with water, may not or not wholly react under very high pressure, at least when the packer is not opened / removed. Release carefully the pressure pushing the ball into the packer

”Soda water phenomenon” while grouting using 1-component PUR 18 bar Grout pressure = CO2 released = start of foaming Grout pressure not released (in the crack) Grout pressure = CO2 released press ready

”Soda water phenomenon” with 1-component PUR – cont. press ready None reacted 1-comp. PU resin + colloidal silica (1 year after grouting!). PUR activated by puncturing of rock mass by drilling → grout pressure = CO2 released = start of foaming

Recommended mechanical packers for 1-comp. PUR grouting Non-return ball valve Recommended mechanical packers for 1-comp. PUR grouting press ready

Non-return ball valve Non-return ball valve Not recommended mechanical packers for 1-comp. PUR grouting. Existing resin pressure cannot be released! press ready

Recommended mechanical packer for 1-comp. PUR grouting Non-return ball valve Non-return ball valve ready

Recommended mechanical packer for 1-comp. PUR grouting Non-return ball valves Not recommended mechanical packers for 1-comp. PUR grouting ready

2. Re-injected water into the packer after completed PUR grouting 1. Pre-injecting of packer with water before starting PUR grouting 2. PUR grouting press ready Remember: pre-inject packer with water before starting grouting and re-inject after completion of injection. After the resin injection, small amount of water must be re-injected into the packers to cure resin left behind (especial important while using hydrophobic resins)

Penetration of PU resin into the crack press ready Penetration of PU resin into the crack press

Excellent penetration of PU resin into the crack (and even around the reinforcement bar) press ready

1 mm PUR in the crack 0.10÷0.30 mm (*) (*) – note openings along PUR fill caused by shrinkage of concrete. Cracks still were completely dry! press ready press

! ! chemical shrinkage in cm3 / 100 g cement time (log) days months   None convenient time of grouting time (log) days months chemical shrinkage vs. time for different water/cement contents Shrinkage causing re-opening of grouted cracks shrinkage in ‰ ! age in days chemical shrinkage vs. time for different water/cement contents ready

Crack and joint repairing in the concrete structures – general remarks !! ! press press ready

Rigid or semi-rigid PU resin recommended for grouting of dormant cracks only ready

End of Part 2 ready