concrete repairs

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SECTION 1100 - CONCRETE REPAIRS 1101 METHODS OF CONSTRUCTION 1102 SURFACE CLEANING 1103 SURVEY AND LOCATION OF DEFECTS A General B Survey photographs C Sounding survey D Covermeter survey E Carbonation depth F Dust samples and chloride content testing G Reinstatement H Survey Report 1104 CONCRETE REMOVAL 6 1105 PREPARATION AND PROTECTION OF REINFORCEMENT 7 1106 REPLACEMENT CONCRETE FOR FOUNDATIONS AND OTHER MEMBERS IN CONTACT WITH THE SOIL 8 A General 8 B Cement 8 C Aggregates 8 D Admixtures 8 E Strength 8 F Minimum cement content and maximum water/cement ratio 8 G Requirements to mixes 8 H Placing 8 1107 REPLACEMENT CONCRETE FOR DECKS AND VERTICAL SURFACES TO PIERS, COLUMNS, AND ABUTMENTS 9 A General 9 B Cement 9 1100-1

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Page 1: Concrete Repairs

SECTION 1100 - CONCRETE REPAIRS

1101 METHODS OF CONSTRUCTION

1102 SURFACE CLEANING

1103 SURVEY AND LOCATION OF DEFECTS

A General

B Survey photographs

C Sounding survey

D Covermeter survey

E Carbonation depth

F Dust samples and chloride content testing

G Reinstatement

H Survey Report

1104 CONCRETE REMOVAL 6

1105 PREPARATION AND PROTECTION OF REINFORCEMENT 7

1106 REPLACEMENT CONCRETE FOR FOUNDATIONS AND OTHER MEMBERS

IN CONTACT WITH THE SOIL 8

A General 8

B Cement 8

C Aggregates 8

D Admixtures 8

E Strength 8

F Minimum cement content and maximum water/cement ratio 8

G Requirements to mixes 8

H Placing 8

1107 REPLACEMENT CONCRETE FOR DECKS AND VERTICAL SURFACES TO

PIERS, COLUMNS, AND ABUTMENTS 9

A General 9

B Cement 9

C Aggregates 9

D Admixtures 9

E Concrete grade and class 9

F Minimum cement content and maximum water/cement ratio 9

G Trial mixes 10

1100-1

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H Placing 10

1108 REINSTATEMENT OF CONCRETE FOR THE SIDES AND SOFFITS OF BEAMS

AND CROSSLINKS 10

A Materials 10

B Water 10

C Class of Concrete 10

D Delivery and storage of materials 11

E Site mixing, placing, and curing 11

F Approval Tests 12

G Batch acceptance tests 12

H Site tests

1109 REPAIR MORTAR 14

A Materials 14

B Delivery and storage of materials 14

C Site remixing, placing, and curing 14

1110 IMPREGNATION 15

A General 15

B Material 16

C Workmanship 17

D Application 17

1100-2

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1101 METHODS OF CONSTRUCTION

The Contractor shall submit full details of his proposed methods of construction to the Engineer for approval including but not limited to the following:

1) details to show safe access and working conditions for personnel, both for the purposes of carrying out permanent concrete repairs and conducting inspection surveys in accordance with this Section of the Specification.

2) details for adequate temporary propping of concrete members at all times during removal and repair of existing concrete.

3) details of equipment and procedures to be used for surface cleaning, removal of concrete, preparation of reinforcement and concrete surfaces for repair,

4) details of proposed repair materials, mix designs, manufacturers’ certificates, and test results showing compliance with specification requirements,

5) details for storage and protection of materials,6) details showing the experience of his proposed operatives to ensure that only competent persons

are employed in the inspection and repair of existing structures. The Engineer may instruct previously approved operatives to be replaced if, in the opinion of the Engineer, they do not demonstrate the level of specialised expertise required.

1102 SURFACE CLEANING

All exposed concrete surfaces shall be cleaned by the Contractor prior to carrying out the inspection surveys and repairs. Before cleaning work begins the Contractor shall remove all surface attachments (signs, notices, electrical fittings etc.) from the areas to be repaired or from positions that obstruct access or which may be damaged. Unless otherwise directed all inserts and fixings which have been cast in or mortared into pockets or otherwise attached to the concrete shall be removed from the area to be repaired. The method of removal shall be such as to avoid unnecessary damage and shall be subject to the approval of Engineer. All electrical supplies to surface attachments shall be sealed off and the mains supply shall be disconnected. All surface attachments shall be carefully stored during the course of the works and refixed, including electrical connections, when all other work is complete.

The cleaning operation shall remove all dirt or other contaminants, previous coatings, laitance, paint, algae, moss, lichens, plant growth etc.

Before any repairs are carried out on any area the surface shall be prepared by:

1) Grit blasting (wet, dry or vacuum blasting) and or2) High pressure water jetting, steam cleaning employing wax free detergents or biocides together

with power scrubbing as required.

The Contractor's proposed method shall be such that no damage is caused to sound concrete. Trial areas shall be carried out on typical locations on the site for the approval of the Engineer before the main cleaning operation commences. The Engineer may instruct a change in the method of surface preparation if the Contractor's proposed method causes damage to the concrete or is otherwise unsuitable.

1100-3

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1103 SURVEY AND LOCATION OF DEFECTS

A GENERAL

The location, number, and extent of defects shown in the Contract are indicative. The true location, number, and extent of defects requiring repair can only be assessed properly by close inspection and other testing once access has been provided and cleaning has been completed.

The Contractor shall carry out a survey of all exposed concrete surfaces to determine the location of defects requiring repair. This survey will include visual inspection, a sounding survey, a covermeter survey and testing of carbonation depth and chloride content. Additional surveying shall be carried out during the course of Contract as agreed by the Engineer. The Contractor shall prepare a survey report for each bridge for review by the Engineer.

B SURVEY PHOTOGRAPHS

During the course of the survey work photographs shall be taken at locations agreed by the Engineer. One set of negatives and two sets of prints shall be provided for the Engineer. Prints shall be of approximate size 150 mm x 100 mm. Prints shall be mounted on A4 sheets with titles by typewriter or similar means and included in the survey reports.

C SOUNDING SURVEY

A sounding survey shall be carried out by striking the concrete surface with a club hammer of 200 grams nominal mass and recording the location of hollow sounding areas. On plane areas of concrete the surface shall be sounded at approximately 300 mm centres in each direction. On columns, beams or other similar members with faces less than 300 mm wide each face shall be sounded near each edge or corner at approximately 300 mm centres along the member. Where a hollow sounding area is detected its extent shall be determined by local sounding and its periphery marked on the surface of the member and the location and extent recorded on the drawings.

D COVERMETER SURVEY

A covermeter survey shall be carried out using methods and equipment as described in GOST 22904-93 Reinforced Concrete Structures – Magnetic Method for Determining Thickness of Concrete Protective Layer and Location of Reinforcement. On plane members the direction of reinforcement with least cover shall be determined. The covermeter head shall be moved across the surface of the concrete along a line in a direction perpendicular to the direction of reinforcement with least cover and with the head orientated in the direction which enables the cover to that reinforcement to be measured. The lines along which the covermeter head is moved shall traverse the full width of the member and shall be approximately 500 mm apart. On columns, beams or other similar members the cover to longitudinal bars shall be determined and recorded at 1m centres along the member. The cover to each stirrup or binder shall be determined and recorded on each face of the member. Where a bar is detected as having less than 20 mm cover for prestressed concrete members or 25 mm for reinforced concrete members, the length having less than this cover shall be determined, the location and extent shall be recorded on drawings and the location marked on the concrete surface.

1100-4

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E CARBONATION DEPTH

Carbonation depth shall be determined and recorded at locations agreed by the Engineer. Carbonation depth shall be determined by breaking off a piece of concrete or taking a small diameter core in a sound area and spraying the fresh fracture surface with phenolphthalein solution using a suitable spraying bottle. The perpendicular depth of the interface between the magenta coloration and the uncoloured concrete from the surface shall be measured. Phenolphthalein solution shall be prepared by dissolving 1g of phenolphalein powder in 50 ml ethyl alcohol and making up to 100 ml with water. The location of the test and the average and maximum depth of carbonation at each location shall be recorded on drawings.

F DUST SAMPLES AND CHLORIDE CONTENT TESTING

Dust samples of concrete for chloride content testing shall be taken at the locations agreed by the Engineer. The area shall be surveyed by covermeter and the sample obtained at a location away from reinforcement. The sample shall be obtained using a rotary percussion drill with bit of 12 mm diameter. The concrete surface surrounding the test area shall be thoroughly cleaned and four holes in a square pattern drilled. Samples from depth increments 0-25 mm, 25-50 mm, 50-75 mm and 75-100 mm shall be collected. The dust from the four holes in each depth increment shall be carefully collected and combined and place immediately in a robust plastic bag which shall be immediately sealed. The sample bag shall be marked indelibly with a discrete sample number on an adhesive label on its outside. The location and sample number shall be recorded on drawings. Chloride determinations shall be carried out in accordance of GOST 25881-83 “Chemical Persistent Concrete. Testing Method” BS 1881 part 124 at a laboratory approved by the Engineer. Results shall be stated as percentage chloride ion by weight of cement

G REINSTATEMENT

Any areas broken out or drilled for the purposes of testing or sampling shall be made good using the repair methods described in this specification.

H SURVEY REPORT

The Contractor shall prepare a survey report for each bridge. Two copies of the report shall be submitted to the Engineer for review. The report shall include details of the visual inspection, sounding survey and covermeter survey, the results of the carbonation depth and chloride content testing, survey photographs, record drawings and all other relevant information.

The extent of the concrete repairs to be carried out on a bridge will be assessed by the Engineer. The areas to be repaired and the type of repair to be carried out at any location shall be as directed by the Engineer.

1104 CONCRETE REMOVAL

The power and size of the equipment used for concrete removal shall be appropriate to the scale of the individual repairs and shall be subject to the approval of the Engineer. Where percussive equipment is used particular care shall be taken that damage is not caused to concrete substrate and reinforcement which is to remain in place.

The extent and depth of concrete removed from a member at any time shall be approved by the Engineer as the work proceeds and shall be methodically recorded on drawings by the Contractor.

1100-5

Page 6: Concrete Repairs

The limits of each repair area shall be cut as a series of straight lines at right angles to the surface to a depth of approximately 10 mm (5 mm for repairs using epoxy mortar) using a disc cutter or similar. The disc cut surfaces shall be roughened prior to reinstatement. Feather edging shall not be permitted.

Where reinforcing bars are exposed by concrete removal, the concrete shall be removed for a minimum of 20 mm behind the bars or until sound concrete is reached, whichever is the greater.

Additional concrete removal shall be carried out along actively corroding exposed bars until a continuous length of 50 mm of bar free from active corrosion is exposed. The limit of active corrosion shall be assessed on a visual basis. The edges of any additional areas removed shall be cut square as specified above.

Where redundant fixings, including lifting hooks, formwork ties and the like, are present on a concrete surface, the concrete shall be removed to a minimum depth of 25 mm around the fixing. The fixing shall then be cut or ground back such that a minimum cover of 25 mm is achieved to the fixing from the concrete surface. The area of concrete broken out shall then be reinstated with repair mortar in accordance with this Section of the Specification.

All necessary precautions shall be taken to ensure that dust or falling debris does not constitute a hazard and effective means of clearing dust and debris away from the working area shall be continuously implemented.

Before concrete removal begins the Contractor shall install temporary propping at locations directed by the Engineer. Temporary propping shall remain in place until the member has been fully repaired and the repair mortar has gained the required strength.

1105 PREPARATION AND PROTECTION OF REINFORCEMENT

Rust scale corrosion products and other deposits shall be removed from reinforcement exposed within the area of repair by grit blasting or other method approved by the Engineer to achieve (ST SEV 4420-83 “Protection from Corrosion in Construction. General Provisions”).

All necessary precautions shall be taken to ensure that dust or falling debris does not constitute a hazard and effective means of clearing dust and debris away from the working area shall be continuously implemented.

Grit blasting shall be carried out in such a way as to include the hidden faces at the backs of bars and at intersections of bars.

Abrasives shall be new, clean and dry and of a grade suitable for the preparation of steel to the standard indicated above. Exhausted abrasive shall be bagged up and removed from site after a single use.

Equipment shall be capable of delivering abrasives at a nozzle pressure sufficient to achieve the standard of cleaning specified above and the air supply shall be free of entrained oil and water.

The exposed reinforcement shall be thoroughly washed down with clean water as part of the preparation operations.

Subject to the approval of the Engineer, the existing reinforcement shall be moved or supplemented or replaced by new bars in accordance with Section 900 of this Specification welded or spliced to existing bars. Bars to be removed shall be cut by disc cutter.

Replacement bars shall be cleaned if required by the Engineer in accordance with the existing Standards specified above. Where bars are lapped a minimum lap of forty times the bar diameter shall be provided.

1100-6

Page 7: Concrete Repairs

All reinforcement shall be adequately fixed and tied in position such that it will not be displaced during the placing of repair materials

After cleaning the surface of the bars shall be coated with a protective system to be proposed by the Contractor for the Engineer’s approval.

The exposed area of the reinforcement shall be completely covered with the protective layer. The first coat shall be applied within 3 hours of cleaning. Any reinforcement remaining uncoated at the end of a 3 hour period shall be recleaned in accordance with this specification prior to application of the reinforcement protective system.

Number of coats, time between coats, mixing, and application of the reinforcement protective system shall be in accordance with the manufacturer's instructions.

1106 REPLACEMENT CONCRETE FOR FOUNDATIONS AND OTHER MEMBERS IN CONTACT WITH THE SOIL

A GENERAL

All replacement concrete in contact with the ground or likely to be contaminated by ground water shall comply with Section 900 of these specifications amended as follows:

B CEMENT

Cement shall be Sulphate Resisting Cement in accordance with Section 200 of this Specification.

C AGGREGATES

The maximum aggregate size shall be appropriate for the repair depth as agreed by the Engineer

D ADMIXTURES

The Contractor shall demonstrate by means of trial mixes the action of the admixture he proposes to use to the satisfaction of the Engineer.

E STRENGTH

The characteristic strength of the concrete shall be 50 N/mm2.

F MINIMUM CEMENT CONTENT AND MAXIMUM WATER/CEMENT RATIO

The cement content shall not be less than 435 kg/m3 and the water cement ratio shall not be greater than 0.40.

G REQUIREMENTS TO MIXES

When tested in accordance in accordance with GOST 10181-2000 “Concrete Mixes. Testing Methods” there shall be no bleed water.

The flow measured in accordance with BS 1881: part 105 shall be greater than 400 mm, without signs of segregation and bleeding.

1100-7

Page 8: Concrete Repairs

H PLACING

Repair concrete shall not be placed without the prior written consent of the Engineer. Before placing repair concrete the exposed concrete surface shall be coated with an approved epoxy resin bonding agent applied in accordance with the manufacturer’s instructions.

Immediately after placing and for 14 days thereafter concrete shall be protected against the harmful effects of weather, including rain, rapid temperature changes, and frost, and from drying out. Alternatively, subject to the approval of the Engineer, impregnation may be carried out after 7 days as described in this Section 1109 of the Specification. The methods of protection used shall in all cases be subject to the approval of the Engineer. Proprietary curing membranes shall not be used.

1107 REPLACEMENT CONCRETE FOR DECKS AND VERTICAL SURFACES TO PIERS, COLUMNS, AND ABUTMENTS

A GENERAL

The concrete shall comply with Section 900 of these specifications amended as follows:

B CEMENT

Cement shall be a mixture of 35% of Ordinary Portland Cement (OPC) and 65% of ground granulated blast furnace slag for use with OPC in accordance with Section 200 of this Specification.

C AGGREGATES

The maximum aggregate size shall be 10 mm.

D ADMIXTURES

The Contractor shall demonstrate by means of trial mixes the action of the admixture he proposes to use to the satisfaction of the Engineer.

E CONCRETE GRADE AND CLASS

The characteristic strength of the concrete shall be 50 N/mm2.

F MINIMUM CEMENT CONTENT AND MAXIMUM WATER/CEMENT RATIO

The cement content shall not be less than 435 kg/m3 and the water cement ratio shall not be greater than 0.40.

G TRIAL MIXES

When tested in accordance in accordance with GOST 10181-2000 “Concrete Mixes. Testing Methods” there shall be no bleed water.

The flow measured in accordance with GOST 7473-94 “Concrete Mixes. Technical Conditions” shall be greater than 400 mm, without signs of segregation and bleeding.

1100-8

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H PLACING

Repair concrete shall not be placed without the prior written consent of the Engineer. Before placing repair concrete the exposed concrete surface shall be coated with an approved epoxy resin bonding agent applied in accordance with the manufacturer’s instructions.

Immediately after placing and for 14 days thereafter concrete shall be protected against the harmful effects of weather, including rain, rapid temperature changes, and frost, and from drying out. Alternatively, subject to the approval of the Engineer, film application may be carried out after 7 days as described in this Section of the Specification. The methods of protection used shall in all cases be subject to the approval of the Engineer. Solid protective films shall not be used.

1108 REINSTATEMENT OF CONCRETE FOR THE SIDES AND SOFFITS OF BEAMS AND CROSSLINKS

A MATERIALS

Cement shall be Ordinary Portland Cement complying with Section 200 of this Specification.

Cement content shall be not less than 420 kg/m3.

Non reactive aggregates shall be used in accordance with the relevant clauses of Section 900 of these specifications or the sodium oxide content shall be restricted to 3.0 kg in any cubic meter of concrete. For these purposes the equivalent sodium oxide in the mix shall be calculated as follows:

Equivalent Na2 O in concrete = a + b + c, where

a is equivalent acid soluble Na2 O in cement, admixtures, and waterb is equivalent water soluble Na2 O in slag and PFAc is chloride ion in aggregates, determined in accordance with BS 812

The total chloride ion content of the materials shall not exceed 0.3 per cent of the mass of the cement. Calcium chloride or admixtures containing chloride salts shall not be used.

The aggregate shall be well graded with the maximum size not exceeding 10 mm and comply with Section 900 of these specifications.

B WATER

If water for the works is not available from a Public Utility mains supply, the Engineer’s approval shall be obtained regarding the source of supply and manner of its use including testing in accordance with Section 900 of this Specification.

C CLASS OF CONCRETE

The specified minimum 28 day strength of the concrete shall be 50 N/mm2 as determined in accordance with Section 900 of this Specification.

1100-9

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D DELIVERY AND STORAGE OF MATERIALS

If the Contractor proposes to use dry mixes he shall supply with each batch or part of a batch of the material delivered to the Site, certificates furnished by the formulators stating:

1) Name and address of Formulator,2) Name and address of Formulator’s agent,3) Material identification,4) Batch reference number, size of batch, and number of containers in the delivery

order,5) Date of manufacture,6) Evidence that the chloride contents are less than specified in this Section of the

Specification,

Containers shall be damp proof and readily emptied of their contentsContainers shall be marked with the following information:

1) Material identification2) Batch reference number3) Formulator’s name4) Net weight5) Any warnings or precautions concerning the contents.

The material shall be stored in a dry environment free from extremes of cold and heat.

When incorporated in the Works the material shall not be older than 3 months or lesser period specified by the Formulator.

The materials shall not be removed from the store for use in the Works until immediately prior to mixing.

E SITE MIXING, PLACING, AND CURING

Mixing and placing shall be carried out in strict accordance with Section 900 of these specifications and, if the Contractor proposes to use dry mixes, in strict accordance with the Formulator’s written instructions. The following additional conditions shall also apply:

1) The water cement ratio shall not exceed 0.4. The water content shall be determined during Approval Tests approved by the Engineer and maintained for Batch Tests, Works Tests, and in the Works within ± 2% of the agreed content.

2) The material shall be incorporated in the Works within 20 minutes of completion of remixing or such lesser period as stated by the Formulator.

3) No extra water shall be added after the original mixing.4) The material shall not be mixed or placed in the Works at ambient temperatures

lower than 50 C.5) The surface temperature of the concrete shall be maintained at not less than 50 C

until the concrete reach a strength of 5 N/mm2 as determined by tests on cubes that were cured under similar conditions to the structural concrete in a manner approved by the Engineer.

1100-10

Page 11: Concrete Repairs

Repair concrete shall not be placed without the prior written consent of the Engineer. The concrete surfaces shall be prepared in accordance with this Section of the Specification or, if the Contractor proposes to use dry mixes, in strict accordance with the Formulater’s instructions.

Replacement concrete shall not be placed against other concrete which has been in a position for more than 30 minutes unless a construction joint is formed in accordance with Section 900 of these specifications. In addition the joint surface shall be saturated for a minimum of 2 hours before concrete is placed against it. When replacement concrete has been in place for 4 hours, or less as directed by the Engineer..

Vibration shall not be used to compact the concrete.

Immediately after placing and for 14 days thereafter, concrete shall be protected against harmful effects of weather including rain, rapid temperature changes, and frost, and from drying out. Alternatively, subject to the Engineer’s approval, film application may be carried out after 7 days as described in this Section of the Specification. The methods of protection used shall in all cases be subject to the approval of the Engineer. Solid protective films shall not be used.

When the mix proportions have been approved by the Engineer no variations shall be made in the manufacture, supply, mix proportions, or method of mixing the material without the consent of the Engineer.

F APPROVAL TESTS

1) General

a) Before work commences on the Site all properties of the proposed replacement concrete shall be demonstrated by the Contractor and, if the Contractor proposes to use a proprietary dry mixes, by the Formulator’s representative, by carrying out tests as specified below in a laboratory approved by the Engineer. Where required in the Contract procedure trials shall be carried out on the model shown in Figure 2 modified to represent actual reinforcement details:

b) The tests shall be carried out in the presence of and to the satisfaction of the Engineer who shall receive certified copies of the results of all tests.

c) The mixer and method of mixing shall be the same as that to be used in the Works

2) Flow trough test

For each flow test sufficient quantity of the replacement concrete shall be mixed in an approved mixer.

The workability characteristics of the concrete shall be assessed at an ambient temperature of between 50 C and 200 C in the flow trough shown in Figure 1

The temperature of the materials and mixer shall be as close as possible to those expected during the Contract.

The funnel shall be fitted with a rubber bung and charged with 6 litres of concrete. On the release of the bung the concrete shall flow along the trough and the length of the flow shall be measured. The minimum length of flow along the trough for each test shall be 450 mm without signs of segregation or bleeding.

1100-11

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3) Flow tests for horizontal soffit shutters repair

The flow characteristics for repairs to soffits shall be assessed by pouring the concrete mix having the same water/cement ratio as in Clause 1108 into the model shown in Figure 2. The pre-cast concrete slab shall be wetted for 2 hours before the test but the surface shall be free of surplus water at the time of test. The concrete shall be poured from one side of the model until the level of the concrete has reached at least 10 mm above the underside of the top plate. The material shall be placed in the model in one pour.

After 24 hours the top plate shall be removed and the exposed surface shall be lightly brushed with a stiff bristle brush to remove any surface cement skin which may be covering voids. The exposed surface of the concrete shall be examined for air pockets, cracks, and other defects.

The temperature of the mixer and material for each test shall be as in Clause 1108 of this Section.

The trial shall be deemed successful if the concrete thus formed is homogeneous and free from voids

4) Compressive strength tests

These shall be carried out to determine the compressive strength of the concrete at 200 C. Test cubes shall be made in 100 mm metal moulds according to GOST 22685-89 “Moulds for Concrete Check Samples. Technical Conditions” BS 1881: part 108. The moulds shall be carefully filled by pouring concrete through a funnel to produce void free specimens. There shall be no compaction. The cubes shall be cured in accordance with GOST 22685-89 “Moulds for Concrete Check Samples. Technical Conditions” BS 1881: part 111. Testing shall be carried out in accordance with GOST 10180-90 “Concrete. Method for determining strength by check samples” BS 1881: part 116.

The specified minimum strength shall be established using a set of three cubes testing. The requirement shall be satisfied if none of the compressive strengths obtained is lower than the specified value, and the difference between the highest and lowest value is not more than 20% of the average.

G BATCH ACCEPTANCE TESTS

Each batch of material delivered to the Site shall be tested as specified below. The material shall be taken at random from one or more containers from the same batch.

Flow tests for horizontal surfaces shall be carried out as specified in Clause 1108 of this Section.

Compressive strength tests shall be carried out as specified in Clause 1108 of this Section.

H SITE TESTS

Repair materials mixed for placing in the Works shall be tested for compressive strength as specified in Section 900 of this Specification.

1100-12

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1109 REPAIR MORTAR

A MATERIALS

Prebatched acrylic polymer modified cementitious mortars shall be used

The water/cement ratio shall not be greater than 0.4

The cement content shall not be less than 435 kg / m3

The total chloride ion content shall not exceed 0.3 per cent of the mass of cement. Calcium chloride or admixtures containing chloride salts shall not be used.

The content of equivalent sodium oxide in the mortar shall be restricted or non reactive aggregates shall be used as specified in Clause 1108 lf this Section.

B DELIVERY AND STORAGE OF MATERIALS

The Contractor shall supply with each batch of the material delivered to site, certificates furnished by the Formulator stating:

1) the polymer used2) evidence that the chloride content is within the limits specified in this Section of the

Specification.

The material shall be stored in a dry environment free from extremes of cold and heat.

The materials shall not be removed from the store for use in the Works until immediately prior to mixing.

C SITE REMIXING, PLACING, AND CURING

Remixing, placing, and curing shall be carried out strictly in accordance with the Formulator’s instructions.

The material shall not be mixed or placed in the Works at ambient temperatures lower than 50 C

The material shall be incorporated in the Works within 1 hour of mixing.

1110 IMPREGNATION

A GENERAL

Numerous existing deck beams have offcuts of steel strand or bar visible or partly visible on their soffits. In general, it is not proposed that these offcuts be removed and the concrete repaired. Instead a protective impregnation coat will be applied to the soffits of existing beams to delay the onset of corrosion.

Impregnation may also be used in conjunction with concrete repairs in accordance with this Section of the Specification.

1100-13

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B MATERIAL

Undiluted monomeric alkyl alkoxy silane (isobutyl) shall be used.

The material shall be delivered in containers sealed by the supplier and stored in a dry covered environment unexposed to direct heat

The containers shall not be opened until immediately prior to application of the material.

C WORKMANSHIP

The work shall be carried out by applicators approved by the Supplier.

D APPLICATION

After 14 days curing of the concrete the material shall be applied evenly in two applications each at a rate of 300 ml / m2 with a minimum interval of 2 hours.

Alternatively the first application may be made after 7 days curing of the concrete followed by the final application not less than 7 days later.

Areas to be treated shall be surface dry and if necessary protected from the weather before application.

Concrete surfaces shall be clean and free from dust and loose matter before treatment. Light grit blasting may be used if necessary.

Material shall not be applied in the following conditions:

1) When the air temperature in the shade is greater than 350 C.2) When the air temperature in the shade is less than 50C.3) When it is raining unless suitable precautions have been taken which have been

approved by the Engineer.

Application shall be made by wet spray without misting at a nozzle pressure not greater than 0.2 N / mm2. The apparatus shall not contain any water.

Figure 1 - Flow Trough and Funnel

1100-14

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300

5

42 Int.

Bung onDrawWire

230

80

3 rad

Section A - A

FunnelDetails

230

80

3 rad.

1000

90°

90°

Rivetedend plate

Trough

A

A

Length o

f flow

measure

d at m

aximum

83

238

1515

3 rad.

hole

10

Funnel Support

This edge to beflush with end

of trough 100

NOTES:1. Trough and funnel to be made of galvanised steel (14 gauge).

2. Trough to be horizontal while concrete being poured.

3. All dimensions in mm.

1100-15

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Figure 2 - Model Flow Test for Horizontal Surfaces

7575

50

10

150 crs. 19

19

750 x 750Pre-cast concrete slabwith rough surface

Plywoodcontaining

walls 600 x 600top glass plate(6 mm float)

Top of Concretein Test

R6 Steel bars at 150 crs.each way mesh placedat mid-depth

Taped Joint

NOTES:-

1. Concrete to be mixed and poured using Contractor’s proposed site apparatus and poured until it reaches underside of top plate and has risen up containing walls to depth of at least 10 mm.

2. All dimensions in mm.

3. Wooden, 20 x 20 spacers at corners required to support glass.

1100-16