All the relevant product data sheets are to be read for additional information like pot life, mixing instructions, surface preparation, ventilation, temperature application limitations, etc.
Structural and Diagnostic Surveys
The essential elements for satisfactory concrete repair work are the correct diagnosis of the cause of damage and the correct choice and application of materials by specialists to meet the particular requirements.
A structural survey shall first be carried out by the owners structural specialist to assess structural integrity and to evaluate repairability. This shall be followed by a diagnostic survey to determine the exact cause and extent of deterioration together with its chances of increasing o recurrence.
The diagnostic survey shall be carried out by a qualified specialist and an assessment made of the types, causes, numbers and extent of defects. (Note: The indications resulting from this survey will depend upon the degree of the examination; also, due to the nature of concrete, will normally allow for variable extent of repairs). The findings shall be presented in the form of a detailed report describing the physical, chemical and other tests carried out insitu and in the laboratory, giving test results and conclusions.
Repair Plan
The repair plan shall be based on findings of the diagnostic survey and other known factors such as the prevailing conditions or limitations under which the repairs are carried out.
Before the work commences the Contract Administrator, specialist contractor and a.b.e.® representative should meet to discuss recommendations for the application of the repair materials and technical advice and information will be offered by a.b.e.®.
The repair plan will be subject to the approval of the building owner’s structural specialist. Unless the approved repair plan recommends otherwise the repairs shall be carried out using only the materials specified and skilled workmen under qualified supervision.
Concrete with Inherent Chloride
The agreed area shall be broken out to remove all contaminated concrete. Where the depth corresponds to the depth of concrete cover and thereby exposes reinforcement, breaking out shall continue to expose the full circumference of the steel and to a further depth of 25 mm or as directed by the Contract Administrator. Breaking out shall continue along the reinforcement until non-corroded steel is reached and shall continue 50 mm beyond this point or as directed by the Contract Administrator. Special care shall be exercised to ensure that any reinforcement exposed is not cut or damaged.
It is essential that no chloride contaminated concrete substrate shall be in contact with, or within 10 mm of, the reinforcing bars. In cases where chloride ingress has reached within 10 mm of the reinforcing bars, the concrete shall be broken out to expose the full circumference of the steel and a further depth of 20-30 mm or as directed by the Contract Administrator.
Where desalination by electro-chemical means is specified, breaking out chloride contaminated concrete will be limited to areas subject to delamination and/or spalling.
All concrete surfaces to receive repair mortar shall be of a rough scabbled nature. Saw/disc cut edges shall be grit blasted to lightly roughen.
This preparation shall be such as to leave a sound exposed concrete substrate free from dust, loose particles and any deleterious matter.
The following shall apply only to areas to be repaired conventionally:
To form a barrier between the chloride contaminated concrete and the repair mortar, the prepared concrete shall be primed with epidermix 345 and allowed to cure for 8 – 24 hours. This coating is to be imperforate and should any unfilled voids (blowholes) be apparent, they shall be filled with epidermix 505 before proceeding.
A second coat of epidermix 345 shall be applied, blinded with dry, dust free, sharp sand and allowed to harden.
Concrete Affected by Carbonation
The agreed area shall be broken out to remove all contaminated concrete. Where the depth corresponds to the depth of concrete cover and thereby exposes reinforcement, breaking out shall continue to expose the full circumference of the steel and to a further depth of 25 mm or as directed by the Contract Administrator. Breaking out shall continue along the reinforcement until non-corroded steel is reached and shall continue 50 mm beyond this point or as directed by the Contract Administrator.
Special care shall be exercised to ensure that any reinforcement exposed is not cut or damaged.
After breaking out as specified the exposed surface of concrete shall be tested for carbonation by the use of a semi-aqueous solution of phenolphthalein. The test shall be carried out on the freshly exposed concrete or at least within 30 minutes of being exposed. The test shall be carried out on sound, dry and clean air-blown dust free surfaces. If the concrete substrate still exhibits carbonation in the vicinity of the steel reinforcement, breaking out to remove a further 20 mm shall be carried out and the test repeated. If carbonation is still present the Contract Administrator shall be notified before proceeding further.
It is essential that no carbonated concrete substrate shall be in contact with, or within 5 mm of, the reinforcing bars. In cases where carbonation has reached within 5 mm of the reinforcing bars, the concrete shall be broken out to expose the full circumference of the steel and a further depth of 20-30 mm or as directed by the Contract Administrator.
Where desalination by electro-chemical means is specified, breaking out carbonated concrete will be limited to areas subject to delamination and/or spalling.
All concrete surfaces to receive repair mortar shall be of a rough scabbled nature. Saw/disc cut edges shall be grit blasted to lightly roughen.
This preparation shall be such as to leave a sound exposed concrete substrate free from dust, loose particles and any deleterious matter.
Reinforcement Priming
The following shall apply only to areas to be repaired conventionally:
Immediately following preparation and cleaning, the reinforcing steel shall be primed with dura.rep ZR primer single component epoxy primer complying with the relevant parts of BS4652, 1971 (1979) Specification For Metallic Zinc Rich Priming Paint Type 2.
The dura.rep ZR primer shall be brush applied to the cleaned reinforcement ensuring that all exposed steel is fully coated. Special attention shall be paid to the backs of the steel bars and where steel bars are tied together. It is essential that this coat is continuous with that of any adjacent repaired area where zinc-rich primer has been used. Avoid excessive overpainting onto the concrete and allow to dry.
Repairs with Formulated Pre-Bagged Mortars / Site Batch Mortars
Repair Areas
The areas to be repaired are to be as shown on the drawings or as indicated by the Contract Administrator. The areas are to be clearly marked out on site and agreed with the Contract Administrator before proceeding.
The areas may be adjusted by the Contract Administrator as work proceeds according to the conditions found.
Propping shall be provided as noted on the drawings or as agreed by the Contract Administrator. The surfaces adjacent to and of areas for repair shall be cleaned to remove any dust, unsound material, plaster, oil, paint, grease, corrosion deposits, organic growth, etc.
Within the repair area, the concrete cover to reinforcement links or main bars shall be determined by cover meter. A small area shall be chiseled out and the concrete cover and the depth of deteriorated concrete confirmed by measurement.
Concrete Repair Using dura.rep FR Repair Material
dura.rep FR mortar with dura.bond GP primer shall be used for vertical or overhead concrete surfaces to be repaired in one or more layers, each layer 10-80 mm thick vertically, 10-50 mm thick overhead, where 22-25 N/mm2 compressive strength and resistance to carbon dioxide and chlorides is required. The minimum depth for repair shall be 10 mm.
Priming Concrete
The prepared substrate shall be thoroughly wetted with clean water to totally satisfy absorption and any standing or excess water shall be removed.
The concrete primer shall be dura.bond GP acrylic emulsion which shall be worked firmly into the damp substrate with a short-bristle brush to achieve a film intimate with the contact area for immediate repair.
Single repair areas larger than 0.5 m2 shall be part primed to commence and thereafter progressively in maximum 0.5 m2 adjacent bays as application of the repair mortar proceeds.
The repair mortar shall be applied whilst the dura.bond GP is tacky.
Repairs to concrete subject to permanent immersion shall be primed with epidermix 345 ‘Slow- set’ which shall be worked firmly into the damp substrate with a short-bristle brush to achieve a film intimate with the contact area for immediate repair.
If the primer dries before the mortar is applied, the area shall be re-primed once.
Mixing Repair Mortar
Before mixing the repair mortar the contractor shall ensure that sufficient and correct areas for reinstatement are prepared and ready to receive repair mortar.
Only mixes using complete bags of dura.rep FR shall be allowed and part bag mixes not permitted.
The mixing shall be carried out strictly in accordance with current product instructions for use and only with appropriate mixing equipment.
The mixing water shall be potable quality and the carefully measured quantity of water for the required mix shall be placed into the mixing container before the dura.rep FR.
The dura.rep FR shall be added to the mixing water and in no circumstances shall more water be added than the maximum volume stated for each bag.
Mixing Warning
As with other ‘one pack’ repair mortars dura.rep FR may exhibit satisfactory handling characteristics even though inadequately mixed. This will result in a significantly lower level of performance or possible failure. It is therefore essential that mixing instructions are strictly adhered to with particular emphasis on the quantity of water used and the time of the mixing operation.
Application of Repair Mortar
Only fully integrated mixes of dura.rep FR at the required consistency and workability shall be used.
Immediately following mixing the repair mortar shall be applied by gloved hand or trowel to the prepared and primed surface of the substrate paying particular attention to packing behind and between the reinforcement and thorough compaction overall.
dura.rep FR shall be applied in accordance with current instructions for use. It may be applied in one operation by building up to the required profile in wet-on-wet layers between 10-80 mm vertically and 10 – 50 mm overhead. Thicker sections may be achieved by building up in wet- ondry layers, where each layer shall be wavy-line scratch keyed with a comb, cured with dura.bond GP, allowed to dry throughout and re-primed at the time of application of subsequent layers.
In hot, humid, coastal situations and in heavy industrial areas ensure that the interval between successive layers is kept to a minimum. This is to prevent possible contamination of the surface of the preceding layer with air-borne contaminants, resulting in possible inter-coat adhesion failure and reduced product performance. In the event that delays are unavoidable, wash down the surface thoroughly with clean water before proceeding with the following coating.
Sagging of the repair mortar is not acceptable and if occurring, all the material of the affected repair shall be completely removed prior to re-priming and refilling in two or more applications of mortar supported by formwork if required.
If formwork is used it shall be pre-treated with a varnish to prevent moisture absorption from the repair mortar. Special care shall be taken to ensure that the positioning of the formwork allows for compaction of and does not result in voids within the repair mortar.
After applying sufficient mortar to achieve a level flush with or slightly proud of the surrounding surface the dura.rep FR shall be finished by striking off with a straight edge and trowelled/floated depending upon circumstances.
Repair mortar shall not be applied when the ambient or substrate temperature is below 5ºC or above 35ºC nor at an ambient temperature of 5ºC on a falling thermometer. The applied repair mortar shall always be protected from freezing whilst drying.
Curing
Details of the methods of curing shall be submitted to the Contract Administrator for approval.
Curing techniques shall be instigated immediately following application of repair mortar to any given area. Large areas (0.5 m2 at a time) shall be cured as trowelling progresses without waiting for completion of the whole area.
dura.bond GP may be low pressure spray applied as a curing membrane. In fast drying conditions it will be necessary to supplement this with polyethylene sheet taped around its edges.
Note: dura.bond GP is compatible with the dura.cote range of surface coatings and does not require removal prior to application of a dura.cote material. Other curing membranes will require removal prior to further surface treatment.
During application and curing all work shall be protected against direct strong sunlight.
Concrete Repair Using dura.rep GT-MCI Repair Material
dura.rep GT-MCI mortar with dura.bond GP/ epidermix 345 ‘Slow-set’ primer shall be used for concrete surfaces to be repaired in 10-30 mm section, small pockets 10-100 mm, overhead repairs 10-20 mm section, each per layer, where 27-34 N/mm2 compressive strength and resistance to carbon dioxide and chlorides is required. The minimum depth for repair shall be 10 mm.
Concrete Priming:
The prepared substrate shall be thoroughly wetted with clean water to totally satisfy absorption and any standing or excess water shall be removed.
Conventional Concrete Repair:
The concrete primer shall be dura.bond GP which shall be worked firmly into the damp substrate with a short-bristle brush to achieve a film intimate with the contact area for immediate repair.
Single repair areas larger than 0.5 m2 shall be part primed to commence and thereafter progressively in maximum 0.5 m2 adjacent bays as application of the repair mortar proceeds.
The repair mortar shall be applied whilst the dura.bond GP is tacky.
Repairs to concrete subject to permanent immersion shall be primed with epidermix 345 ‘Slow-set’ which shall be worked firmly into the damp substrate with a short-bristle brush to achieve a film intimate with the contact area for immediate repair.
If the primer dries before the mortar is applied, the area shall be re-primed once.
Mixing Repair Mortar:
Before mixing the repair mortar the contractor shall ensure that sufficient and correct areas for reinstatement are prepared and ready to receive repair mortar.
Only mixes using complete bags of dura.rep GT-MCI shall be allowed and part bag mixes not permitted. The mixing shall be carried out strictly in accordance with current product instructions for use and only with appropriate mixing equipment.
The mixing water shall be potable quality and the carefully measured quantity of water for the required mix shall be placed into the mixing container before the dura.rep GT-MCI.
The dura.rep GT-MCI shall be added to the mixing water and in no circumstances shall more water be added than the maximum volume stated for each bag.
Mixing Warning:
As with other ‘one pack’ repair mortars dura.rep GT-MCI may exhibit satisfactory handling characteristics even though inadequately mixed. This will result in a significantly lower level of performance or possible failure. It is therefore essential that mixing instructions are strictly adhered to with particular emphasis on the quantity of water used and the time of the mixing operation.
Application of Repair Mortar:
Only fully integrated mixes of dura.rep GT-MCI at the required consistency and workability shall be used.
Immediately following mixing the repair mortar shall be applied by gloved hand or trowel to the prepared and primed surface of the substrate paying particular attention to packing behind and between the reinforcement and thorough compaction overall.
dura.rep GT-MCI shall be applied in accordance with current instructions for use. Apply in one operation, minimum total thickness is 10 mm, and well compact into repair voids, paying particular attention to compaction around reinforcing steel.
Where the depth of the void is in excess of 30 mm vertically (except for small pockets) or 20 mm overhead, the repair mortar shall be built up in wet-on-dry layers. The repair shall be temporarily finished off at the maximum single application thickness, wavy-line scratch keyed with a comb, cured with dura.bond GP and allowed to harden. It shall then be reprimed at the time of application of the next layer.
In hot, humid, coastal situations and in heavy industrial areas ensure that the interval between successive layers is kept to a minimum. This is to prevent possible contamination of the surface of the preceding layer with air-borne contaminants, resulting in possible inter-coat adhesion failure and reduced product performance. In the event that delays are unavoidable, wash down the surface thoroughly with clean water before proceeding with the following coating.
Sagging of the repair mortar is not acceptable and if occurring all the material of the affected repair shall be completely removed prior to re-priming and refilling in two or more applications of mortar supported by formwork if required.
If formwork is used it shall be pre-treated with a varnish to prevent moisture absorption from the repair mortar. Special care shall be taken to ensure that the positioning of the formwork allows for compaction of and does not result in voids within the repair mortar.
After applying sufficient mortar to achieve a level flush with or slightly proud of the surrounding surface the dura.rep GT-MCI shall be finished by striking off with a straight edge and trowelled/floated depending upon circumstances.
Repair mortar shall not be applied when the ambient or substrate temperature is below 5ºC or above 35ºC nor at ambient temperatures of 5ºC on a falling thermometer. The applied repair mortar shall always be protected from freezing whilst drying.
Curing
Details of the methods of curing shall be submitted to the Client’s Representative for approval.
Curing techniques shall be instigated immediately following application of repair mortar to any given area. Large areas (0.5 m2 at a time) shall be cured as trowelling progresses without waiting for completion of the whole area.
dura.bond GP may be low pressure spray applied as a curing membrane. In fast drying conditions it will be necessary to supplement this with polyethylene sheet taped around its edges.
Note:
dura.bond GP is compatible with the dura.cote range of surface coatings and does not require removal prior to application of a dura.cote material. Other curing membranes will require removal prior to further surface treatment.
During application and curing all work shall be protected against direct strong sunlight.
Repairs with Fluid Micro-Concrete – dura.rep FMC Fluid Micro-Concrete
dura.rep FMC high performance, shrinkage compensated micro-concrete suitable for large volume concrete repairs at nominal thicknesses in excess of 50 mm. Supplied as a premix requiring only mixing with water to‘ produce a free flowing material, for placing by hand or pump. The low water requirement ensures fast strength gain and longterm durability.
Formwork:
Adequate formwork shall be provided in accordance with the relevant codes of practice. It shall be constructed from appropriate materials as agreed with the Contract Administrator and shall be watertight at all joints between panels, and between formwork and the existing concrete.
The formwork shall be securely fixed to withstand the hydraulic pressures of the fluid micro-concrete without distortion or movement during and subsequent to placement. It may be necessary to divide into suitably sized sections.
Formwork surfaces that are to be in contact with the fluid micro-concrete shall receive two coats of polyurethane shutter paint and be treated with a suitable release agent such as dura.strip in accordance with current instructions for use.
The formwork shall include bottom drainage outlets for pre-soaking water, provision for introduction of the microconcrete and air venting as required. The introduction and venting points shall be located so as to avoid any possibility of entrapment of air, etc. Where necessary provision shall be made for controllable venting points to prevent air entrapment and enable the extent of flow of the fluid microconcrete to be assessed.
In hot, humid, coastal situations and in heavy industrial areas ensure that the interval between priming the reinforcement and erecting the shutter is kept to a minimum. This is to prevent possible contamination of the bond line with airborne contaminants, resulting in possible bond failure with the substrate. In the event that delays are unavoidable, wash down the surface thoroughly with clean water before erecting the formwork.
Pre-soaking (unless priming with epidermix 345):
The formwork shall be inspected by the Contract Administrator and if approved, the void filled with clean water and kept full. This shall remain for a minimum of 2 hours, then the formwork shall be completely drained and resealed immediately prior to introducing the fluid micro- concrete.
Priming Concrete Having Inherent Chloride:
The following shall apply only to areas to be repaired conventionally:
To form a barrier between the chloride contaminated concrete and the new concrete, the prepared concrete surface shall be primed with epidermix 345 and allowed to cure for 8-24 hours. This coating is to be imperforate and should any unfilled voids (blowholes) be apparent, they shall be filled with epidermix 505.
A second coat of epidermix 345 shall be applied, which, depending upon requirements may be (A) immediately followed by the shuttering and pouring of the microconcrete, or (B) blinded with dry, dust free, sharp sand and allowed to harden before pouring the micro-concrete.
Pre-soaking with water is unnecessary in this case and shall not be permitted.
Mixing Micro-Concrete:
Only mixes using complete bags of dura.rep FMC shall be allowed and part bag mixes shall not be permitted.
The mixing shall be carried out strictly in accordance with current product instructions for use and only appropriate mixing equipment will satisfy.
The mixing water shall be potable quality and the carefully measured quantity of water shall be placed into the mixing container before the dura.rep FMC.
The dura.rep FMC shall be added to the mixing water and in no circumstances shall more water be added than the maximum volume specified for each bag.
Mixing Warning:
As with other ‘one pack’ repair mortars dura.rep FMC may exhibit satisfactory handling characteristics even though inadequately mixed. This will result in a significantly lower level of performance or possible failure. It is therefore essential that mixing instructions are strictly adhered to with particular emphasis on the quantity of water used and the time of the mixing operation.
Concreting:
When assessed in accordance with the flow measurement requirements of DTP BD27/86 the dura.rep FMC shall flow 750 mm along the test trough within 30 seconds, without segregation or bleeding.
Test cubes may be made at intervals if required by the Contract Administrator. They shall be made in 100 mm metal mould to BS1881:Part 108. The mould shall be carefully filled to avoid air entrapment.
There shall be no compaction and the top of each cube shall be covered by a metal plate with a weight not less than 0.5 kg. The cubes shall then be cured and tested in accordance with the relevant parts of BS 1881.
Poured material shall be introduced slowly into the formwork. It may be introduced via a funnel, or hopper, at the top of the formwork, unless the configuration of the repair necessitates the use of external pipe-work to reach remote parts of the void. The entry point(s) shall be designed to provide sufficient head of material to ensure total displacement of air.
The placing of the dura.rep FMC shall be, as far as possible, continuous. The requirements of DTP BD 27/86 permit a maximum 20 minutes between completion of mixing and placing.
Mixing shall be timed so that there is minimal interruption to material placing. If, however, placing is interrupted, this shall be brought immediately to the attention of the Contract Administrator. The operation may continue while the dura.rep FMC retains its flow characteristics.
Where fluid dura.rep FMC is poured in sections, the previously cast edge at the stop end face shall be suitably roughened and cleaned.
dura.rep FMC shall not be placed when the ambient or substrate temperature is below 5ºC or above 35ºC nor at ambient temperatures of 5ºC on a falling thermometer. In cold conditions down to 5ºC the use of warm water, up to 30ºC shall be permitted for pre-soaking and mixing.
Formwork Removal:
The formwork shall not be removed until the dura.rep FMC has achieved a compressive strength of at least 10 N/mm2 or as directed by the Contract Administrator.
Curing:
Details of the methods of curing shall be submitted to the Contract Administrator for approval.
Curing techniques shall be instigated immediately following application of repair mortar to any given area. Large areas (0.5 m2 at a time) shall be cured as trowelling progresses without waiting for completion of the whole area.
dura.bond GP may be low pressure spray applied as a curing membrane. In fast drying conditions it will be necessary to supplement this with polyethylene sheet taped around its edges.
Note:
dura.bond GP is compatible with the dura.cote range of surface coatings and does not require removal prior to application of a dura.cote material. Other curing membranes will require removal prior to further surface treatment.
Curing shall be instigated immediately after removal of the formwork and continued for at least 3 days.
During application and curing all work shall be protected against direct strong sunlight.
Concrete Fairing – dura.rep FC
dura.rep FC single component polymer modified fairing coat shall be used. It is designed for application to a maximum thickness in one coat of 3 mm. dura.rep FC may be feather edged.
Use:
For fairing following concrete repair; filling blow-holes and similar imperfections; providing an ideal background for subsequent surface coatings overall. dura.rep FC is not designed as a surface finish in its own right.
Surface Preparation:
All surfaces shall be sound, clean and free from dust, plaster, oil, paint, grease, corrosion deposits, laitance, organic growth and any other deleterious substance.
Surfaces shall be cleaned by mechanical means, steam, pressure washing with clean water, grit blasting, or a combination to satisfy. Any remaining dust or loose material should be removed by blowing with oil-free clean compressed air.
Mixing:
The mixing shall be carried out strictly in accordance with current product instructions for use and only with appropriate mixing equipment.
Mixing Warning:
As with other ‘one pack’ repair mortars dura.rep FC may exhibit satisfactory handling characteristics even though inadequately mixed. This will result in a significantly lower level of performance or possible failure. It is therefore essential that mixing instructions are strictly adhered to with particular emphasis on the quantity of water used and the time of the mixing operation.
Application:
The prepared concrete shall be thoroughly saturated with clean water and maintained in this condition for minimum 30 minutes prior to application of dura.rep FC.
Using a steel trowel and a scrape-on scrape-off technique, blow-holes, imperfections and the like, shall be filled flush to the surrounding surface.
Where the overall surface, or areas thereof, require fairing to produce a smooth, regular surface, further apply the fairing as a render to a maximum thickness of 3 mm. This shall be a separate operation after blow-hole filler has completely dried. Finish with a steel trowel or sponge float to blend to adjacent areas, or according to instructions of the Client’s Representative.
dura.rep FC shall not be applied when ambient temperature is below 5ºC or 5ºC and falling. Protect dura.rep FC from rain and from freezing for at least 48 hours after application.
In hot, humid, coastal situations and in heavy industrial areas ensure that the substrate is washed down thoroughly with clean water prior to the application of dura.rep FC. This is to prevent possible adhesion failure as a result of contamination with air-borne contaminants.
Curing:
Provision for curing need only be made where dura.rep FC is exposed in conditions of very rapid drying.
Where curing is necessary, dura.bond GP shall be applied by low pressure spray to the surface as finishing proceeds.
Surface Coating – dura.cote WB
Surface Coating:
The surface coating shall be dura.cote WB water based pigmented elastomeric acrylic topcoat having excellent crackaccommodation available in the a.b.e.® range of colours. Use in conjunction with dura.cote WB primer penetrating, hydrophobic, silane-siloxane/acrylic primer.
Use:
For application to prepared backgrounds of atmospherically exposed reinforced and pre-cast concrete and masonry where it is required to minimise ingress of carbon dioxide, chlorides and water, whilst permitting moisture vapour transmission from the structure.
Survey:
Areas recently prepared overall with dura.rep FC in accordance with a.b.e.® specification will present a surface suitable to directly receive a coating system.
Areas where the previous works have not taken account of the need to prepare the overall surface to receive a coating (small patch repairs with little or no fairing e.g.) shall be the subject of an inspection identifying the background character, nature and surface presentation. Information shall be provided to the Contract Administrator detailing the areas for surface coating and the degree of preparation proposed together with techniques to be employed. The technical approval of the Contract Administrator shall be obtained prior to commencement.
Where required by the Contract Administrator trial areas not exposed in the finished work shall first be treated using selected materials. These trial areas shall be noted on the drawings and shall be carried out using the type of materials, mixing procedures and application techniques that will be used in the contract and shall be approved before the contractor commences the general work. Colour and finish to be agreed by the Contract Administrator.
Surface Preparation:
All surfaces shall be sound, clean and free from dust, plaster, oil, paint, grease, corrosion deposits, laitance, organic growth and any other deleterious substance.
Surfaces shall be cleaned by mechanical means, steam, pressure washing with clean water, grit blasting, or a combination to satisfy. Any remaining dust or loose material should be removed by blowing with oil-free clean compressed air. Blowholes, cracks, imperfections and areas of pitting shall be made good with dura.rep FC in accordance with current product information for use.
In hot, humid, coastal situations and in heavy industrial areas ensure that the interval between successive coatings is kept to a minimum. This is to prevent possible contamination of the surface of the preceding coating with air-borne contaminants, resulting in possible inter-coat adhesion failure and reduced coating performance. In the event that delays are unavoidable, wash down the surface thoroughly with clean water before proceeding with the following coating.
Application:
Only the specified areas shall be coated; where protection/ masking is required, dependent upon the nature of the coating and its method of application, it shall be provided and installed to the approval of the Contract Administrator. During application, walkways, plants, joint sealants, asphalt and bitumen painted areas and glass shall be masked and shielding shall be provided to prevent animal contact and to prevent airborne coating materials leaving the immediate area of application.
Thoroughly mix all materials in their original containers and progressively intermix containers of the same colours as the job proceeds.
Surface coating materials shall not be applied in rain or when rain is likely within 6 hours of application.
The primer shall not be applied when ambient and/or background temperatures are below 5ºC or 5ºC and falling. The topcoat shall not be applied when the ambient and/or background temperatures are below 5ºC or 5ºC and falling. Protect all surface coatings materials from frost whilst drying.
Primer:
Special care shall be taken to ensure that the recommended application rate of 0.4L/m2 is achieved and two or more applications may be necessary until the dried surface presents a uniform sheen. The primer shall be allowed to dry for not less than 2 hours at 20ºC, longer when cooler.
Topcoat:
Two coats of dura.cote WB shall be applied. Each coat shall be applied at a minimum wet film thickness of 400 microns. The drying time between coats shall be minimum 16 hours at 20ºC and over-coating shall not take place until this period has elapsed and the prior coat is dry. Under poor drying conditions at low temperature it is permissible to apply three coats each of 270 microns wet film thickness.
The finished coating shall be continuous, pin-hole free and have a minimum dry film thickness of 400 microns.
The colour and finish is to be as agreed with the Contract Administrator.
Surface Coating for Immersed Conditions – duraflex Surface Coating
duraflex® is a two-component polymer modified cementitious coating, developed for use as an internal coating for potable water retaining structures such as water storage reservoirs and water towers.
The total dry film thickness (dft) shall be not less than 1.8 mm and shall be capable of providing CO2 diffusion resistance equivalent to not less than 125 mm of 30 MPa concrete cover (Taywood method using Klopfer’s criteria). It shall provide protection against chloride ingress showing no measurable ingress after 400 days immersion under accelerated testing conditions (Taywood Method).
Use:
For application to prepared backgrounds of reinforced and pre-cast concrete and masonry where it is required to minimise ingress of chlorides, CO2 and water, whilst permitting moisture vapour transmission from the structure.
Survey:
Areas recently prepared overall with dura.rep repair mortars in accordance with a.b.e.® specification will present a surface suitable to directly receive a coating.
Areas where the previous works have not taken account of the need to prepare the overall surface to receive a coating (small patch repairs) shall be the subject of an inspection identifying the background character, nature and surface presentation.
Information shall be provided to the Contract Administrator detailing the areas for surface coating and the degree of preparation proposed together with techniques to be employed. The technical approval of the Contract Administrator shall be obtained prior to commencement.
Surface Preparation:
All surfaces which are to receive the coating must be free from oil, grease, wax, dirt or any other form of foreign matter that might affect adhesion. Good quality concrete surfaces can be cleaned using a high pressure water jet. Poor quality, friable, or contaminated concrete may require grit blasting.
Spalled surfaces or those containing large blow holes, cracks and other such defects should be repaired using a suitable dura.rep repair mortar.
If the surface contains small blow holes, typically less than 3 mm wide, or cracks no wider than 300 μm, the coating can be applied directly on to the substrate without the need for a repair mortar.
Only the specified areas shall be coated; where protection/ masking is required, dependent upon the method of application, it shall be provided and installed to the approval of the Contract Administrator.
Mixing:
Pour the liquid component (5 L) from the plastic container into a plastic or metal drum having a volume of at least 20 litres. Gradually add the powder component (20kg) to the liquid whilst mixing with a propeller agitator attachment on a slow speed drill (400-600 rpm unloaded). Continue mixing, constantly moving the agitator around the drum, until a lump free consistency is achieved. Mixing is continued for a minimum of 3 minutes, stopping at least once to scrape any unmixed powder from the side of the drum into the mixture.
Application:
The prepared substrate shall be thoroughly wetted with clean water to totally satisfy absorption and any standing or excess water shall be removed. In very porous substrates, particularly in hotter climates, saturate the surface, leave for 1 – 2 hours, then saturate again. Ensure excess water is removed before proceeding.
The material shall not be applied when the ambient or substrate temperature is below 5ºC or 5ºC on a falling thermometer. The applied coating shall always be protected from rain and frost whilst drying.
The coating can be applied by soft bristled brush, medium haired roller or steel trowel. A special spray unit has been developed by a.b.e.® for large contracts. Consult your local a.b.e.® representative.
The first coat should be applied at a minimum wet film thickness of 1 mm. Monitor the coating thickness during application at regular intervals using a wet film comb gauge. Care must be taken to check that all blow holes and other imperfections are filled during application. If not, this can be done while the coating is still wet by using a dry sponge. If the coating has dried before these imperfections are found they can be filled using fresh material.
Allow to cure for a minimum of 4 hours @ 20ºC/50 % RH. This time can be reduced substantially in hotter climates.
All the mixed material should be used within 45 minutes of mixing. In hot, humid, coastal situations and in heavy industrial areas ensure that the interval between successive coatings is kept to a minimum. This is to prevent possible contamination of the surface of the preceding coating with air-borne contaminants, resulting in possible inter-coat adhesion failure and reduced coating performance. In the event that delays are unavoidable, wash down the surface thoroughly with clean water before proceeding with the following coating.
The second coat should also be applied at a minimum wet film thickness of 1 mm. Monitor the coating thickness during application at regular intervals using a wet film comb gauge. Pre-dampening of the surface is not necessary when applying the second coat.
Finishing:
To produce a smooth finish or to repair film defects use either a steel trowel, caulking tool or hard sponge. This should be done immediately after application, otherwise the coating may drag or tear.
When using a hard sponge it should be dry or very slightly damp. A wet sponge should not be used as this will cause polymer to come to the surface of the coating that causes an unsightly white streaky effect.
Curing:
Under normal conditions of application, no curing is required.
Products Required
- abe® super brush cleaner
- dura.bond GP
- dura.cote WB
- dura.cote WB primer
- duraflex®
- dura.rep FC
- dura.rep FMC
- dura.rep FR
- dura.rep GT –MCI
- dura.rep ZR primer
- epidermix 345
- epidermix 505
Equipment Needed
- Heavy duty Festo mixer with helical mixing head
- Pan Mixer Suitable 25 litre containers
- Steel trowel
- Steel float
- Spatula
Important Note
This data sheet is issued as a guide to the use of the product(s) concerned. Whilst a.b.e.® endeavors to ensure that any advice, recommendation, specification or information is accurate and correct, the company cannot – because a.b.e.® has no direct or continuous control over where and how a.b.e.® products are applied – accept any liability either directly or indirectly arising from the use of a.b.e.® products, whether or not in accordance with any advice, specification, recommendation, or information given by the company.
Further Information
Where other products are to be used in conjunction with this material, the relevant technical data sheets should be consulted to determine total requirements.