FLEX O PATCH SURFACE REPAIR OF PQC

Methodology - PQC Repair.

a) Identification & planning of repair is being done at a place after detailed survey

and inspection.

b) Open the crack or widened the pothole till we get sound base surface and space

to have anchorages with Elastomeric Concrete - Flex “O”Patch.

c) Opening of the cracks & potholes please refer point no. M. In any case edge

preparation should be such that the prepared edge of the repaired area should

have 90º Angle or obtuse angel with respect to the surface to have a better

anchorage.

d) With the help of angle grinder slot should be cut in the edges for anchorages.

e) Blow of the complete area with the blower till we get the area which should be

free from oil, grease, dust, durt, etc.

f) Wires brush the complete area along with the edges. Also wire brush 10 mm area

around the edges on the top side & again blow the area. CLEANING OF THE

SURFACE IS VERY MUCH IMPORTANT, AS PERFORMANCE OF EC IS

TOTALLY DEPENDS ADHESION.

2

g) Fixing masking tape adjacent to the surface area to avoid spillage of Flex

“O”Patch on other surfaces.

h) Primer: Applying the recommended primer to have better anchorages. Wait for

minimum 30 Min ( Drying of primer depends on surrounding temperature) to dry

the applied primer. Use clean brushes for application of primer always. Avoid

the pounding of primer.

i) Block out area should be ready for pouring the material before mixing.

3

j) Mixer – by using Hobard mixer (or equivalent) recommended for mix the fast

setting compound with controlled speed of peddle which can be made available at

all sites on request of contractors or officer on paid basis.

k) Mixing Flex “O”Patch: Need to Mix 3000 ML part A & 1000 ML part B & 1 bag of

Sand of 6 Kgs. at a time for one batch. Pour Part A & B simultaneously in mixing

bowl & immediately after that empty the entire sand & fibre bag in to the bowl It

should be completed in 10 – 15 Seconds. Run the mixer for 50 Sec maximum &

immediately pour mix material in to the prepared block out as the material is self

leveling pour it from one end to other end till the block out areas is fully covered.

This is done to the potential of avoid the de-lamination.

l) Tooling or re-leveling of Flex “O”Patch wherever its required

4

m) Giving surface texturing to the Flex “O”Patch to give anti-skidding

properties

n) Removing of masking tape after 10 minutes

5

o) Waiting period 1 hour

p) Repaired surface opened to the traffic with any load just after 1 hour

from the last pouring of Flex “O”Patch - Elastomeric concrete which is

not possible by any conventional method of repairs & rehabilitation of

concrete surfaces.

6

q) The whole procedure of repairs of concrete surface will take maximum

2 – 4 hours depend on the type of surface.

r) Some Thumb Rule for the repair works :

?????? For Surface cracks : Width of the opening should be minimum 50 mm &

Depth 30 mm or till we get sound concrete.

?????? For Major Cracks: width of the opening should be minimum 80 -100 mm &

Depth 35 mm or till we get sound concrete or aggregates are exposed.

?????? Potholes : We need to keep depth till we get sound concrete or minimum 30

mm whichever is more.

?????? Aggregate Exposed Area: Length & Width should be as per the defected

area & minimum depth should be 25 mm.

?????? Edge Spall Repairs: Need to open minimum 75 mm both side of joints if

spalls are found on both side & Depth should be 40 mm or till we get sound

concrete.

?????? Other Areas of spall : Minimum 40 mm on one side or both side as required.

 

PQC  CRACK REPAIR

METHEDEOLOGY FOR REPAIR  FOR PQC LONGITUDINAL AND TRANSVERSE CRACKS

 

    SEALING OF STRUCTURAL CRACKS IN EXSISTING PQC   BY EPOXY RESIN

                                    

 

The structural crack    which is dormant are observed and   marked with marker. The

Width of crack is measured.

 

The   PQC  Slab  are  checked  for identifying   fractured  section in PQC  slab when identified  and Core sample is taken to study the depth of Crack  it is marked and injection port is provided accordingly

 

Material: The material for injection shall be suitable two –component low viscous epoxy resin having the required characteristic of bonding with concrete and résistance to moisture Penetration.

 

Batching of Resin:  Mixing ratio of the resin and hardener shall be 2:1 or as per manufacturer specification. The entire mix to be injected within stipulated time through injection ports as

Per manufacturer Specification.

 

Working Temperature: Not more then 30*Celsius   to 34* Celsius

 

 

Surface Preparation: Surface adjacent to cracks or other areas of application shall be cleaned of dirt,dust,grease,oil,oil and efflorescence or other foreign matters  by brushing/water jetting/sand blasting.

 

 Injection (Entry) Ports shall be provided along the line of cracks at interval not more than thickness of concrete at the location. It is placed by drilling by power rotator   hammer  drill

Up to 1/3  rd thickness of concrete section.

 

Surface seal material shall be applied to the face of the crack between the entry ports. For through cracks, surface seal shall be applied to both faces

 

Before Proceeding for injection grouting the surface seal material must gain adequate strength with respect to concrete strength of the member/injection Pressure.

 

Equipment for Injection Grouting

 

Epoxy grouting EQUIPMENT IS MANUALLY OPERATED   PUMP  which can inject up to 2kg/sq-cm . It is portable positive displacement type pump. It has intake as well as delivery pipe with Nozzles.                                                                                                                                              Repair By Stitching or Cross-stitching of Cracks

CRACK STICHING FOR ARRESTING LIVE CRACK ON PQC

 

Cross-Stitching is a repair technique mostly used for longitudinal cracks which are in reasonably good condition. The purpose of cross-stitching is to maintain aggregate interlock and provide added reinforcement for strength. The tie bars used in cross-stitching prevent the crack from vertical and horizontal movement or widening. This technique knits the cracked portions of the slab together and reduces the chances of crack to grow further.

Cross-stitching uses deformed tie bars drilled across the crack at an angle of 30-40 degrees. Deformed steel bars of 10-12 mm diameter are sufficient to hold the crack tightly closed and enhance aggregate interlock. Full depth holes of 18-20 mm diameter are drilled at a pitch distance of 300 mm with offset of about 150 mm from the crack. The holes are drilled alternately from each side of the crack so that it passes through the crack from left to right, while the next from right to left. After drilling, the holes are flushed with high pressure air to clean out any residual dust. Then a high strength epoxy gel adhesive is injected into the hole. Immediately after injecting epoxy, deformed steel bars are inserted into each hole. The crack is sealed at the top with silicon / epoxy modified sealant.

 

 

 

 

 

 

Repair   of Longitudinal/Transverse Partial Cracks accompanied with Cluster of Cracks in all direction accompanied with de-bonded concrete Section

 

  Work Preparation                      

 On both sides of crack, the side edges be slightly chiselled to give a V-shape. If required do chiselling until a hard concrete is encountered.

 Remove loose material from crack area and blow out the dust and   debris from the gap of crack by using a compressor or air blower.

 

 Drill holes in PQC surface in the line of Crack up to depth of about 100mm~150mm / 10mm @ spacing 300mm~400mm.

 

Fix the Packers in the injection Ports by Epoxy resin and silica flour mix or Epoxy Putty

Procedure

Surface to be repaired may be pre wetted or bring it in SSD condition.

Apply a coat of primer like acrylic bonding agent using brush after scrubbing it well on the prepared surface. Allow the primer to become tacky, which normally takes 10 – 15 minutes or as given in the manufacturer literature.

Push the Compressed air into the crack to flush out the dust and all foreign material from the crack to the side or top.

 

Fill the top of V-grove portion by appropriate Epoxy modified mortar.

Use the epoxy repair compound or free flowing epoxy resinous grouting material or similar product of very low viscosity.

Prepare the mix of the repair material as directed by manufacturer or Mix them mechanically with Grout mixture after weighing them in recommended proportions.

Recommended water quantity (if water based) will be measured and added to polymer component and mix it thoroughly. The powder component will be mixed until a homogeneous mix is obtained.

Pressure Inject the above material or appropriate ultra low Viscosity epoxy liquid first in the middle nozzle from one side of crack. Continue till it is forced out of next nozzle or from the side of PQC crack. Then shift the injection procedure to next nozzle. After the injection is complete, estimate the consumption of grouting material or find out the quantity of injected material. This may be compared with the estimated quantity.

If possible ask a supervisor from the suppliers of material to supervise the job as per their recommended procedure and specifications during the use of product.

Apply the mix within the pot life of repair compound on the prepared crack.

   Finishing of Repair Surface of Crack

If sagging on surface occurs during application to PQC surface, then Polyurethane based coating may be applied by trowel in smaller thickness in one or two layers.

The applied mortar shall be finished with wooden floats.

When the injection operation is over then cut the projected portion of nozzles and sealing the portion by Epoxy Mortar.

After completion of repair of the joints, spalls, partial depth repair, corner repairs, etc sealing of expansion joints should be done immediately using polyurethane coating otherwise joints might leak & will create problems in future.

 

EPOXY MORTAR PATCHING

The concrete substrate must be sound and of sufficient compressive strength (minimum 20 N/mm2) with a minimum pull off strength of 1.5 N/mm2.

The substrate must be clean, dry and free of all contaminants such as dirt, oil, grease, coatings and surface treatments, etc.

 Concrete substrates must be prepared mechanically using abrasive blast cleaning, scarifying or grinding equipment to remove cement laitance and achieve an open textured surface

Weak concrete must be removed and surface defects such as blowholes and voids must be fully exposed.

Repairs to the substrate, filling of blowholes/voids and surface leveling must be carried out using appropriate products   Epoxy resin mortar

The concrete or screed substrate has to be primed or leveled in order to achieve an even surface.

 

 The Epoxy   bonding agent need to be applied@0.6kg/sq-m.

Mix of Epoxy Mortar to be laid by trowel in 25 mm thick layers

Successive layer to be installed after 12 hours and   Last layer of 25 mm after 6 hrs

 After 12hrs Polyurethane Coating 2 coats of Clear Colors to be done  Over it

Traffic to be released after 72 hrs in winter season and 48 hrs in summer season.

Epoxy mortar coverage=2kg/mmthickness/sq-m

1) Polymer concrete With Carbon   Fiber Filament or Grid Mesh/Steel Staples admixed with Non Metallic Floor Hardener Float Finish.

 1). 1:1.5:3 [OPC:SAND:6mm down aggregate] +40% w/c  Acrylic Poymer to be added .

 2.) While batching in Mixture Carbon fibers/Corrugated Stainless Steel  Staples to Approx  600gms to be added with 500 gms of Non Shrink dry Powder compound and this batch to be further mix for 5 Minutes in Portable Mixture.

3. The Area to be patched has to Applied with Epoxy Bonding Agent @0.6kg/Sq-m and whilst it is tacky the   Polymer mix is  placed  and  by Surface Vibrator it is Vibrated

4. After 15 mts  Non Metallic Floor Hardener Carborandum based Preferably is broadcasted over the surface of fresh concrete@6kg/sq-m and  it is  floated  and smooth surface is achieved  which is later textured.

5.   After 12   Curing Compound is coated over it .

6. Opened for traffic after   7 days.