Guidelines for Repairing of Concrete Pavement

What is Concrete Pavement?:

Concrete Pavements also known as Rigid Pavements have a relatively long service life, provided these are properly designed, constructed and maintained. Concrete Pavements are known to perform better with minimum maintenance. The concrete pavements can serve up-to its design service life and even beyond, if timely repairs are undertaken. Concrete is a very good and strong material, but it develops cracks due to temperature, shrinkage, creep etc. Until unless enough precautions are taken, some cracks do come up on concrete surface. Prominent cracks should be repaired for better performance and longer life of Highways/pavements. To repair these cracks, several materials and procedure have been developed. The efficiency of these materials and procedures depend on the type of crack, weather conditions and applicator efficiency.

Definition :

Base Concrete : The upper(structural) layer of portland cement concrete with varying in site strength, typically 25 to 50 Mpa.The plain or reinforcement concrete may contains various forms of steel reinforcement, dowels and tie bars. In some instances concrete may contain steel fibre reinforcement. The following are the four types of concrete pavements :
1) PCC : Plain concrete.
2) CRCP : Continuously Reinforced concrete pavement.
3) RCP : Joint Reinforced Concrete Pavement.
4) SFCP : Steel fiber reinforced concrete pavement.

Types of Distress and Their Causes :

Understanding the causes of pavement distress is essential for providing appropriate effective repair and developing maintenance strategies. This guide suggests that the best way to identify the cause of pavement distress is to conduct site condition survey on a regular basis.Two goals of the condition survey to and the structural assessment are determine the root cause of the pavement distress and rate of pavement deterioration.

• Structural Distress : All cracks are not structural cracks. Structural cracking is often caused due to excessive loading, long joint spacing, shallow or late sawing of joints, restraint at base or edge, due to joint lock-up, inadequate thickness, material related problems, etc. Use of proper construction techniques and traffic load control can reduce/avoid such structural cracks, Structural defects affect the pavement capacity to carry the traffic. Cracking and joint deterioration are typical structural distress. Use of proper construction techniques and traffic load control can reduce/avoid such structural cracks.

• Plastic shrinkage cracking : Plastic shrinkage cracks are tight , about 0.3m to 0.6 m long formed in parallel groups perpendicular to the direction of the wind , at the time of paving. Plastic shrinkage cracking occurred due to the Excessive water at surface (bleeding"),hot windy conditions & rapid drying at the pavement surface. The Adequate curing measures are necessary to prevent their occurrence.

• Drying shrinkage cracking : Wider/deeper cracking is usually attributable to the drying shrinkage and restraint developed in the concrete due to inadequate joint spacing, improper saw cutting . The optimum spacing of joints in a jointed concrete pavement depends on the slab thickness, sub-base stiffness and concrete strength. Pavement with long transverse joint spacing may otherwise develop full panel width deep cracks due to tensile stresses developed due to temperature curling.

• Longitudinal Cracks : Excessive  drying shrinkage stresses ,Insufficient depth of joint or late joint sawing.Excessive joint  spacing.Sudden/abrupt thermal and moisture gradient changes. Channelize or static heavy loading, viz. truck parking. Loss of sub-grade support ,for instance poorly compacted sub grade.Settlement of embankment which leads to subsequent settlement of slabs.

• Transverse Cracks : Tensile stresses in concrete are more than tensile strength  of Concrete. Excessive  drying shrinkage  stresses.Inadequate depth and/or late initial joint  groove sawing.Excessive joint spacing or length /width ratio of slab more than 1.5.

• Diagonal Crack: Excessive  drying  shrinkage  stresses. Excessive thermal and moisture gradient stresses. Excessive joint spacing.Unstable  sub-grade  or  loss  of  sub-base  support (settlement of utility trench, etc.).Excessive over loading.Frost action.

• Corner Breaks : Poor load transfer.

• Durability Distress :It is caused by the premature deterioration of concrete such as D cracking and alkali aggregate reaction.

• D Cracking is D shaped hairline cracks that occurs near joint,crack and free edges when certain aggregates in a concrete become saturated,freeze,and expand.The expansion causes the surrounding concrete matrix to crack.

• Alkali: Aggregate Reaction is caused by a chemical reaction that occurs when free alkalies in the concrete combine with certain siliceous aggregate to form an alkali – silica gel.As the gel forms,it absorb water and expand,which cracks the surrounding concrete.

• Functional Distress : These distresses do not necessarily reduce the load carrying capacity of the pavement but affect the riding quality,and safety.Roughness,loss of surface texture,surface defects etc.

• Loss of Surface Texture, Polished Surface/Glazing/ Smooth Surface : Movement of construction traffic at an early age.Wear and tear under high volumes of traffic particularly under wet or uncleaned surface.Poor  texturing  during  construction.Frequent  braking and  turning  sections.Non  durable concrete.Surface Defects comprise scaling, popouts, crazing,and plastic shrinkage cracking.Scaling is caused by overworking the surface;popouts are due to reactive or absorptive aggregates;while crazing and plastic shrinkage cracking are usually the result of poor curing procedures.Surface Polishing is the wearing away of the surface texture to expose the concrete coarse aggregate on heavily trafficked pavements.It leaves the surface smooth and reduces the pavement skid resistance and surface friction capabilities.

• Joint deterioration : Such as spalling,breaking,cracking,chipping, or fraying of the slab edges usually occur within 50 mm of joint.Such deterioration starts when incomressibles enter and become lodged in the joints or cracks during cool weather. As the temperature rises the slab expand,causing high compressive stresses in the concrete which result in joint deterioration . The deterioration result in more incompressible entering the joint or crack causing further deterioration.

• Spalling at Cracks or Joints : Ingress of stones and other incompressible material into joint Dynamic traffic loads at slab ends, mechanical  damage Weak concrete, poorly compacted or non durable, particularly at construction joints or defects of dowel load transfer system.

Traffic loading and environmental influences:

The concrete pavement is further exposed to traffic loading and environmental influences, namely temperature and moisture which can have the following effects:-                                                                                         
Traffic related distress causes are the most widespread and frequent.They usually act in combination with climatic causes.Axle loads are responsible for fatigue and impact failure of the materials of different pavement layers including the pavement slab. They also originate structural cracking both shallow and full depth and vertical differential movements of the concrete slabs.Wear by traffic tires-results in loss of texture and consequential functional distress of the pavement surface.
Moisture decreases the bearing capacity of underlying layers, facilitates abrasion and internal erosion. Surface water ingress in the pavement structure shall be prevented by properly sealed joints and by timely sealing of cracks. However sealing materials deteriorate with time and therefore a properly designed and operational pavement sub-surface drainage shall be provided so that any percolating water does not remain entrapped within the pavement. If these conditions are not fulfilled and water is trapped in or between the pavement layers it will be subjected to high pressure and may be expelled under passing traffic loads carrying fine materials (pumping) in suspension that result from internal erosion of the pavement materials.

Factors causing deterioration in concrete :

• Corrosion damage due to attack from Carbonation & Chloride.                                                                            
• Corrosion due to moisture leaks.
• Honey Combing
• Surface interfection/cracks
• Physical damage : Impact,erosion,earthquake
• Chemical attack,pin hole /blow hole.

Assessing Maintenance Needs :

The evaluation of the exiting pavement condition is the most essential part of the process of assessing the maintenance needs.
The main types of maintenance required in respect of cement concrete pavements are as follows :

• Routine Maintenance: A proactive approach consist of various work activities required to be carried out in a consistent,scheduled (almost regular) basis around the year, such as monitoring the condition of the pavement , keeping the pavement and joints clean and free of stones and debris, restoring damaged and eroded shoulders and other such road side activities which can be generally managed in a day or so in one particular stretch.

• Programmed Maintenance: These are reactive spot/incidental repairs such as filling of portholes with specified materials and other generally planned activities such as resealing the defective joint sealant, cross-stitching, partial depth repairs, full depth repairs and diamond grinding to remove faults in the rigid pavement.

• Rehabilitation and Strengthening: It refers to major restoration or upgrading of the pavement like diamond grooving for restoring surface texture, slab stabilization, reconstruction or application of an overlay to rectify structural inadequacy in the pavement over lengths typically in the range of 1 km or more and thus to extend the serviceable life of the pavement.Emergency Repairs: It covers responding to complaints or emergencies.

The repairs are usually performed by skilled (sometimes specialist) labor engaged on a periodic and planned basis.

Methods for repairing concrete pavement :

These are mainly classifieds in to two methods :
1.Preventive Methods, 2.Corrective Methods

1.Preventive Methods :

• Joint and crack resealing : Joint and crack resealing minimizes the infiltration of surface water and incompressible reduces the potential for spalling and blow-ups.

• Retrofitting concrete shoulders : Retrofitting concrete shoulders adds a tied concrete shoulder to an existing pavement. It is similar to dowel-bar retrofit because it decreases the critical edges stresses and corner deflection and reduce the potential for transverse cracking,pumping,and faulting,retrofit concrete shoulder can decrease the outside pavement edge deflection and cantilever action,which reduced the potential for punchouts.

• Retrofitting edge drains : Adding a longitudinal drainage system to a pavement aids in the rapid removal of water and may prevent pumping,faulting and durability distress from developing.

2.Corrective methods :

Corrective technique are used to repair a given distress and improve the serviceability of the pavement.

• Repair of minor Cracks (Hair Line Crack<1 mm wide)

These are very low (small) width cracks or hairline cracks. Such cracks generally do not affect the performance of road surface. Thus these cracks, unless the severity level increases, need not be repaired. Further observe these cracks over a period of time for enlargement.

• Medium Cracks (generally 1 to 5 mm wide)
  

If cracks are not moving then a very low viscosity epoxy resin may be used for its repair with or without fine sand to bond the crack faces. V shaped ‘joint wells’ are made with 3 to 5 mm saw blade. Also make 8 to 10 mm diameter grout holes at regular interval. Then pump the epoxy bonded into holes using a grout gun.

• Full depth repairs :

It involve the following steps :
1.Define repair boundaries area.
2.Saw old concrete
3.Remove old concrete.                                                      
4.Prepare patch area.
5.Provide load transfer.
6.Place and finish concrete.
7.Cure and insulate concrete.
8.Saw and seal joint.

• Partial – depth repairs : It is the process of removal & replacement of small areas of deteriorated ( or spalled ) concrete, typically in joint or crack. The depth of deterioration can vary from a few mm to to the full depth of pavement. Once they begin, spalls tend to grow or propagated under repeated thermal stresses & traffic loading. Partial depth repairs restore structural integrity and improve ride quality. Repairs of partially deteriorated joint areas also restore a well defined ,uniform joint sealant reservoir prior to joint resealing.

• Cross-stitching of Cracks :

Cross stitch is a process of drilling alternately inclined holes into concrete techniques outlined in the concrete pavement restoration guidelines in ACI concrete repair.

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 injection 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 epoxy mortar like Kem Mortar EP 1.

Prerequisite Activities for All Types of Repairs:

• General

All repair techniques discussed in the guidelines will start with the following preparatory activities:
Marking out the areas to be repaired. Making the temporary working area safe for the workmen from the passing traffic by temporary barricading,signage etc. Dismantling the affected areas and disposing of the broken concrete in an appropriate way. Any other activities as per the direction of the Engineer-in-Charge .

• Marking areas to be repaired

The following activities shall be undertaken for appropriately marking out the area to be repaired.
The total distressed and surrounding areas (to be repaired) are marked on the pavement in rectangular form with sides parallel and perpendicular to the center line after chiseling with a hand hammer, ensuring not less than 50 mm cutting beyond unsound concrete . Rectangular areas simplify saw cutting and concrete removal.
All full depth repairs shall be made the full width of a lane to achieve stable patches and provide adequate room in the pit for dowel hole drill rigs and compaction equipment.
The area to be repaired for a full depth transverse crack shall be a transverse strip. The width will depend on the crack alignment. Odd shaped slabs (L/B > 1.5) and mismatched slabs shall be reinforced with 10 mm dia bars placed at depth of 75 mm from the top and 200 mm CIC both ways.
If the transverse crack is close to a joint (< 1500 mm from the joint) one of the sides of the area to be repaired shall be the nearest joint itself.
The newly cut joint faces shall be scabbled with a chisel or sand blasted to create roughness for better bond between old and new concrete.
Partial depth repairs are usually smaller than 1 m2.For partial depth repairs if the distance between patches is smaller than 300 mm, the patches are combined in a single large patch.
When two different areas to be repaired or patches are close to each other the repair may be faster and cheaper if the adjacent areas are combined in a large patch.
The criteria for combining adjacent full-depth patches depend on slab thickness and the patch in case of (partial width repair) or lane in case of (full-width repair) width.

• Layout for a Repair of Wide Full Width Cracks (d >D/2)/Full Depth Repair (FDR):

The following activities shall be undertaken:
The layout recommended for repair of full width transverse cracks depends on the location of the crack with respect to the joints and free edges.
Transverse cracks extending full width of the panel or continuous longitudinal cracks . intersecting with formed or sawn joints are not acceptable in new construction i.e. before "Taking Over" from the contractor by the client as per IRC: 15 and MoRT&H Specifications for Road and Bridge Works. However, these may be provided with tie or dowel bars as part of a short term maintenance strategy after "Taking Over". Dowel bars shall be used in such conditions where widening of the crack may occur.
For cracks at a distance of more than 1.5 m from the next transverse joint, slots for retrofitting of dowel bars shall be cut and the dowel bars placed at distances of 250 - 300 mm before the crack is widened and sealed. This is a stop gap arrangement. The permanent treatment would be to make a full slab replacement or cutting out the affected part of slab by full depth cutting. Holes are made for tie bars and additional contraction joint is made by providing dowel bars.
For cracks located at short distances from joints (ie. at less than 1.5 m) the strip of slab between the crack and the joint shall be cut to a regular rectangular shape and removed. The condition of the existing dowel bars shall be checked and new holes for new tie bars shall be drilled in the opposite sawn cut face. These shall be thoroughly cleaned with compressed jet air and filled with a thick epoxy. The tie bar shall be inserted by hammer imparting light thuds at the head of the tie bar so that the epoxy oozes out insuring complete bond between the circular wall of the hole and ribbed surface of the tie bars. The epoxy shall be allowed to cure for a minimum period of four hour.
If the slab displays two or more than two full width cracks complete slab reconstruction shall be considered or repair may be carried out as per the advice of Engineer-in-Charge.
The concrete faces with tie bars shall be scabbled/sandblasted to give a rough key to the new concrete. The pit shall be filled with the approved concrete mix,compacted and textured to match the surrounding slabs. Before concreting the bottom and sides of the pit are kept wet for few hours(not less than 4 hours). The condition of surface should be Saturated Surface Dry (SSD). Some agencies use cement: sand 1:1 slurry with w/c ratio not more than 0.62 to coat the sides and bottom of pit(the slurry should not be allowed to dry). While pouring fresh concrete, it shall be placed in central portion of the pit first and then worked towards edges ensuring complete vibrations including in the comers.

• Cutting and Removing Debris

Saw cutting and chipping are the operations required to remove the unsound concrete within the marked area and leaving a rectangular patch pit of uniform depth. The sidewalls of the pit to be cut are usually specified as vertical and the vertical sections of the pit are rectangular.
Special care shall be taken not to damage the adjoining panels when chipping concrete for full-depth patches. For this purpose chipping of the slab concrete shall only take place after making a cut at a distance of 50 mm into the sound panels. Within this area additional saw cuts may be made to expedite removal of slab pieces.After the concrete inside the delineated area has been chipped and removed,the remaining strip between cuts and joints can be safely removed.
If the repair extends up to the slab joint insert a piece of oiled shuttering ply in the adjacent joint(s) to avoid percolation of patching material in the joint.

• Saw Cutting and Lifting Procedure for Full Depth Repair and Whole Slab Replacement :

It comprises of the following procedure:
The marked area is sawn with diamond blade saw in pieces or whole according to availability of crane or other machinery to lift and remove slab pieces.
The remaining pieces of slab left over tie bars and dowel bars is broken in such a way that the concrete in the adjacent good slab is not damaged.
Lifting the whole piece of concrete imparts no damage to the sub-base and is readily done. This method requires less labor than breaking the concrete before removing. Different types of equipment can be used to lift the slab or slab portion by means of a chain connected to lift pins: torque claw attachments for front-end loaders, forklift devices and vertical bridges.

• Work Safety and Traffic Diversion :

Before the repair work is carried out, the proper traffic diversion shall be planned and implemented in consultation with the Engineer-in-Charge having full regard to the statutory and contractual provisions for safety. All signals required for traffic diversion and work safety shall be brought to the site and placed at appropriate sections and distances. When the work is finished and curing completed all debris and traffic control measures shall be removed and normal traffic conditions restored.

• Disposal of Dismantled Materials :

The concrete dismantled during partial depth repair/ full depth repair/ grinding and grooving etc. shall be suitably disposed off as provided in the contract.
These guidelines, however, recommend the following steps for the disposal of dismantled materials:

The concrete should be broken to sizes not greater than 0.02 cm and stacked neatly in the ROW (Right of Way) for later reuse or till it is finally disposed off as per contract.
The chunks should be sorted into range of sizes, with larger chunks (less than 0.02 cum in size) broken further by hand or put in the crusher to break them into smaller size particles so they can be reused as an aggregate for non structural purpose.

Equipment for Repair :

Depending upon the method of repair the following equipment may be used:

• Grouting Pump of capacity about 5-10 Kg/cm2.
• Mechanical Grout Mixer,
• Air Compressor,
• Injection Packers,
• Hand Chisel, trowel, etc.

Guidelines for repairing cracks, bug holes and other minor defects :

1. Application Procedures for repairing dry cracks on concrete surfaces -

• Surface Preparation : Slightly chiseled to give a V-shape. If required do chiseling 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. Using a marker pen,locate drill position between 150 mm to 200 mm centers along the entire length of the crack. At drill location, drill a hole into the concrete approximately 20 mm deep using 6 mm drill bit.

• Fixing injection packers: The injection packers shall be inserted into pre drilled holes at intervals along the length of each cracks. The distance between each packer will depend on the width and depth of the crack. Spacing shall be close enough to ensure that the resin will penetrate along the crack. This will normally be between 200 mm to 500 mm. The surface of the cracks between the packers shall be sealed with a patch of Kem Gell EP to the next point of injection on both sides of crack, the side edges , 30 mm to 40 mm wide and 2-3 mm thick. Both side of any cracks which go all the way through a concrete shall be sealed in this way. In the case of concrete which is cracked all the way through, packers shall be located on both sides with those at the back placed at midway point between those at the front. The Kem Gell EP shall be allowed to cure for 8 hour at 350 C at low ambient temperature (50 C – 120 C). The curing time will be extended and the applicator shall ensures that the surface sealant adequately cured prior to continuing.

          One end of the injection hose shall be attached to the lowest packers on vertical cracks or to      either end or horizontal crack.

• Mixing: Prepare the two components of Kem Inject ELV by mixing of 78 g Resin and 22 g Hardener by weight. Mix only enough material which can be used in the workable life of the mixed material which is normally 25 minute at 300C.

• Application: Commence injection from the lowest packers. Locate the on-off valve to the packer. Switch the valve on the gradually apply pressure to the gun, filling the cracks with Kem Inject ELV continue applying pressure until resin appears at next packers location or until no more resin will enter the crack. Remove or switch off the valve,remove the gun from the packers and crimp move the next location. Continue injection resin until all packers locations have been sealed. When the supervising officer is satisfied that the crack has been sealed sufficiently,finish operation & allow to cure for six hour.Clean the injection pump by using solvents i.e Xylene or Butyl Acetate. Remove all Kem Gell EP and packers from the concrete by suitable means such as angle grinder or similar.

Finishing of Repair Surface of Crack When the injection operation is over then cut the projected portion of Packers Seal the surface of cracks between the packers with a patch of Kem Gell EP, 30 mm to 40 mm wide & 2 to 3 mm thick. Both sides of any cracks which go all the way through a wall or slab shall be sealed in this way. Curing of Repaired Surface Kem Gell EP does not require the application of curing compound.

2. Application Procedures for repairing Bug Hole & other minor surface defects :

• Surface preparation : Using medium pressure water blasting, or by mechanically abrading the concrete surface laitanace to expose fully all blow holes or other surface imperfections. Ensure that all surrounding concrete is free from dust and other deterious substances. If water blasting is done allow to concrete to dry for 24 hr.                                                                                                                                   

• Mixing : Mix entire content of base and hardener together in a mixing bucket until a uniform lump free mix is obtained. Apply the mixed Kem Mortar EP1 to the prepared surface using a steel trowel . Finish theb surface by using water wet trowel.( Note – Water should not be added directly to the mix or splashed on the applied surface).

• Curing : Kem Mortar EP1 does not require the application of curing compound.( Note – If large areas rather than pockets are repaired, it is recommended to use Kem Seal EP 110 as a priming coat along with Kem Mortar EP1.)

3. Application methods for resurfacing of Concrete Surface :

• Surface preparation : Using medium pressure water blasting, or by mechanically abrading the concrete surface laitanace to expose fully all blow holes or other surface imperfections. Ensure that all surrounding concrete is free from dust and other deterious substances.  

• Mixing : Use a mixing bucket suitable for mixing in excess of 15 lit and dampen the side . Ensures no excess water remains. Measure out the correct amount of water( 2.3 to 2.7 lit) and pour into the buckets. Slowly add Kem Mortar HS/Kem Mortar MT to the water and mix using a slow speed drill and spriral paddle. Continue mixing for a minimum period of 3 minutes until uniform mix is obtained. Priming ; For thin section 5 to 15 mm Kem Bond EP1 epoxy resin bonding agent. Mix Kem Bond EP1 untill a uniform consistency has obtained. Apply  over the concrete substrate using a stiff bristle brush. Apply the repair mortar between 4 to 8 hr at 200C and  3-6 hr for 3500C. Use Kem Bond AR acrylic emulsion bonding agent for onshore repairs.                   

• Application : Compact Kem Mortar HS./Kem Mortar MT into the primed substrate by trowel or gloved hand. Kem Mortar HS can be applied at a minimum thickness of 5 mm to maximum thickness 20 mm at horizontal application. Greater thickness can be achived in a serious of layers with each layer scracthed and allowed to reach initial set. Then soak surface with water and prime the Kem Bond AR slurry and apply second layers. Further layers may be applied in similar way. Finish the material by striking off with a straight edge and close the surface using a steel trowel. On completion of repair,cure with Kem Bond AR applied by knapsack sprayer,roller or brush.

                                                                                                     

Repair Material :

Chembond Offered following repairs materials:

Sr. No.	Products	Description	Uses
1	Kem Epoxy Grout ELV	It is epoxy based,two  pack low viscosity injection resin.	Used to seal cracks  in dry concrete.  It is suitable for repairing structural  cracks.
2	Kem Mortar  EP-1	It epoxy based,two components  fairing facing thixotropic mortar.	Used to sealing cracks,blow holes  making fair slightly damaged  pavement concrete
3	Kem Gell EP	It is epoxy based two components  multipurpose adhesive.	Used as surface sealant for crack  injection system.
4	Kem Mortar H.S.	It is single component,cement based  polymer modified repair mortar.	Used for repairing  damage concrete.
5	Kem Mortar F.S.	It is cement based rapid setting mortar.	Used for quick repairs of horizontal  concrete surfaces.
6	Kem Mortar MT	It is single component,cement based  polymer modified repair mortar.	Used for repairing  damage concrete.
7	Kem Cure AID 10W	It is white pigmented synthetic wax  based emulsion.	Used on concrete construction in  order to avoid fast drying of the  surface.
8	Kem Bond AR	It is latex modified acrylic bonding agent.	Used for bonding old concrete to new  concrete.
9	Kem Inject PU 2K	Polyurethane based flexible low viscosity  crack injection grout.	Used to seal cracks into dry,damp or  wet concrete or masonry.
10	Kem Bond SBR	It is a styrene butadiane rubber based liquid.	Used for bonding old concrete to new  concrete freshly placed concrete.
11	Kem Bond EP 1	It is solvent free epoxy resin based system.	Used for bonding old concrete  to new concrete freshly placed  concrete.
12	Kem Bond EP 2	It is two component water based  epoxy resin system.	Used for bonding old concrete to new  concrete freshly placed concrete.