C – Civil Engineering (Highway Structures and Bridges)

 

This information is provided as assistive only and may not be complete. The revised MCHW documents should be read to confirm the full extent of the technical changes and how they apply to particular work aspects. All liability for the use and interpretation of this information remains solely with the user.

CC 400 – Permanent Road Restraint Systems

  1. The schedules in each of the product sections of CC 400 give a framework (in the WSR) for the Specifier to provide clearer and more detailed requirements for the specification of all permanent road restraint systems.
  2. The maintenance and repair requirements which previously only applied to legacy vehicle restraint systems, now apply throughout Section 2 of CC 400. This means that the requirements now apply to all road restraint systems which are not covered by a harmonised and/or designated standard (i.e. permanent terminals, transitions, pedestrian restraint systems, removable barrier sections, arrester beds, anti glare screens attached to a vehicle restraint system, and arrester beds), not just legacy vehicle restraint systems.
  3. The guidance in Clause 404.2 of the Notes for Guidance to Series 400 has been converted into a requirement in Clause 3.42 onwards (for vehicle restraint systems) and Clause 10.27 onwards (for pedestrian restraint systems) of CC 400 (The testing frequency of anchorages in drilled holes shall be one per post anchorage group for the first 5 groups, and one per five anchorage groups thereafter for each length of parapet system installed)
  4. Clauses 3.33 (for vehicle restraint systems) and 10.18 (for pedestrian restraint systems) of CC 400 include a new requirement that the serviceable life of the post holding down system (now termed ‘anchorage’) to be the same as, or greater than, that of the road restraint system which is connected to it.
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CC 401 – Permanent Legacy Road Restraint Systems

The schedules in each of the product sections of CC 401 give a framework (in the WSR) for the Specifier to provide clearer and more detailed requirements for the specification of all permanent legacy road restraint systems.

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CC 402 – Temporary Vehicle Restraint Systems

  1. The schedules in each of the product sections of CC 402 give a framework (in the WSR) for the Specifier to provide clearer and more detailed requirements for the specification of all temporary vehicle restraint systems.
  2. The maintenance and repair requirements which previously only applied to legacy vehicle restraint systems, now apply throughout Section 2 of CC 400, and these are called up for the temporary products covered by CC 402.
  3. The option of the Overseeing Organisation providing the temporary safety barrier (or indeed, any temporary vehicle restraint system) has now been removed.
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CC 481 – Minor Structures

Environmental barriers (including noise barriers) have been moved from Series 2500 to new CC 481, which covers minor structures. Noise barriers are now considered Minor Structures, reflecting in changes to CD 354 made previously.

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CC 482 – Structural Concrete

  1. Specification provisions for the use of self-compacting concrete have been added, as appropriate, in various sub-sections of Section 6 (Concreting) of the new CC 482. The provisions are aligned with the standard provisions on the topic contained in the latest BS EN 206 and BS 8500. Note, the use of self-compacting concrete is an additional option available for selection as part of the choices related to the concrete mix design.
  2. Specification provisions for the use of steel and polymer fibres in structural concrete have been added, as appropriate, in various sub-sections of Section 6 (Concreting) of the new CC 482. The provisions are aligned with the standard provisions on the topic contained in the latest BS EN 14889 and the Concrete Society Technical Reports TR63 and TR65. Note, the use of steel and polymer fibres in structural concrete is an additional option available for selection as part of the choices related to the concrete mix design.
  3. Specification provisions for the use of recycled aggregates in structural concrete have been added, as appropriate, in various sub-sections of Section 6 (Concreting) of the new CC 482. The provisions are aligned with the standard specification provisions on the topic contained in the latest BS EN 12620, BS EN 13055, BS EN 206, BS 8500 and the WRAP quality protocol for inert waste. Note, the use of recycled aggregates in structural concrete is an additional option available for selection as part of the choices related to the concrete mix design.
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CC 483 – Structural Steelwork

No notable changes.

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CC 484 – Concrete Repairs

  1. New requirement (CC 484, clause 2.11) for cleaning of existing concrete surfaces (pressure jetting assumed) prior to pre-breakout visual survey to confirm repair extent or as part of a additional concrete investigation.
  2. New requirement (CC 484, clause 3.14) to remove surfacing down to concrete deck before executing any saw cutting of deck to prepare a straight edge for subsequent removal of bulk concrete using hydro-demolition.
  3. New optional requirements (CC 484, clause 3.28) relating to concrete removal when working around prestressing strands and post-tensioning ducts.
  4. New option (CC 484, clause 4.25) for specifying design by Contractor of repairs to concrete in highway structures, permanent legacy road restraint systems or concrete open drainage channels in accordance with the DMRB (CS 462). Also new option CC 484, clause 6.4 for specifying contractor design of soffit repairs using flowable concrete.
  5. New options for surface preparation of steel reinforcement (CC 484, clause 8.54, SIs 8.54a and 8.54b). Default standard for surface preparation for existing corroded bars of Sa2.5 to BS EN ISO 8501-1 may now be changed to St 3 (hand preparation) or increased to Sa 3 (grit/sand blasting) at discretion of the designer/specifier. Other steel substrates e.g. steel structural sections normally encased in concrete may be prepared to a lesser standard using hand tools (St2, St3) or more onerous standard (Sa3) using grit blasting. Guidance for designer/specifier will be in DMRB (CS 462). The designer specifier can specify a different preparation standard in special cases.
  6. New requirements (CC 484, from clause 8.26 to 8.94 – see example clause 8.31) to formalise, improve and extend the specification for on-site welding of new reinforcing bars when required to replace or supplement existing reinforcement. Can also be used for small shallow weld repairs to damaged reinforcement.
  7. Clarification of frequency and location for measuring the electrical potential of anodes (CC 484, clauses 9.85 – 9.89). Frequency reduced from all of the anodes to a smaller proportion e.g. 20% of electrical potential mapping surveys or 10% of total anodes for galvanic anode installations within repairs. Survey may be carried out when repair concrete is only 14 days old.
  8. New requirement (CC 484, clauses 9.67 and 9.68) for installation of cabling needed when a designer specifies that a galvanic anode system installed within repair patches should be monitored for voltage and current
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CC 486 – Protection of Steelwork against Corrosion

  1. A high build solvent free paint has been included for application to internal faces of steel box girders replacing the two types of water-based paint systems.
  2. A high build two pack fluoropolymer F.E.V.E. resin based top-coat has been added for maintenance painting.
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CC 487 – Maintenance Painting of Steelwork

  1. Short Possession Paint System (SPPS) has been added where access is limited (bridges over railway where possession is required for maintenance).
  2. A high build solvent free paint has been included for application to internal faces of steel box girders replacing the two types of water-based paint systems.
  3. A high build two pack fluoropolymer F.E.V.E resin based top coat has been added for maintenance painting.
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CC 488 – Waterproofing for Concrete Structures

  1. Reduction in the number of longitudinal ducts from 4x100mm to 2x100mm (with one subducted).
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CC 489 – Bridge Bearings

No notable changes.

CC 490 – Bridge Expansion Joints and Sealing of Gaps

No notable changes.

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CC 491 – Masonry

  1. Clauses 1.14 & 1.15 provides a means for site-won masonry units to be tested and used.
  2. Clause 3.4 requires the acid-soluble sulfates category for aggregates to be specified.
  3. Clause 5.16 additional clause to differentiate between the requirements for factory made mortar and mortar mixed on site.
  4. Clauses 8.1, 8.5 & 8.6 provides requirements for autoclaved aerated concrete masonry units.
  5. Chapter 9 provides requirements for manufactured stone for facework.
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CC 495 – Miscellaneous

  1. MCHW CC 495, Section 1 Preworks laboratory LT tests. Number of pre-works laboratory suitability tests reduced to 3 no. for each proposed proprietary (manufactured) bedding mortar and each contract. Responsibility for the three tests removed has been transferred to the product manufacturer to carry out and declare.
  2. MCHW CC 495, Section 1 Preworks laboratory LT2 test. Clause 1.83. Additional thermal toughening of 6mm thick float plate glass plates to lower risk of damage to the apparatus after it is dismantled for cleaning after each test.
  3. New requirement for formal written report of pre-works laboratory testing. MCHW CC 495, Section 1 Documentation for tests. Clause 1.135. Formal reporting of pre-works laboratory suitability test results for bedding mortar.
  4. New requirement. MCHW CC 495, Section 1 Installation of bedding mortar:
    • Clause 1.139, Existing concrete substrate to be roughened before placing bedding mortar.
    • Clause 1.154 Protection of bedding mortar material installed in plinth from high temperatures above 25 C for 24 hours after installation.
  5. New requirement. MCHW CC 495, Section 1 Installation verification. Clause 1.159 Site trial of bedding mortar placement method is required where mortar is specified under structural bearings. Specifier Instruction allows designer to specify other situations where a trial will be necessary e.g. under gantry baseplates.
  6. MCHW CC 495, Section 2, clause 2.1 Designated concrete type complying with BS 8500 required for all concrete intended for ancillary purposes and will replace Standardised prescribed concrete.
  7. MCHW CC 495, Section 2 Clause 2.31 Requires designated type (GEN, RC) concretes for ancillary purposes. CC 495 specifies an enhanced requirement of chloride class 0.4 for designated concrete mixes other than GEN1 (e.g. GEN 2, GEN 3, RC 20/25 etc).
  8. New requirement. MCHW CC 495, Section 2, cl 2.20 Coarse crushed concrete aggregate (CCA) of normal reactivity permitted for GEN1 and GEN2 concretes up to 20% mass fraction.
  9. New requirement. MCHW CC 495, Section 2, cl 2.54. Concrete suppliers check of chloride content of designated concrete mix by calculation.
  10. MCHW CC 495, Section 3, Table 3.14. Single size 40mm aggregate no longer specified in BS EN 12620 aggregate standard, so difficult to source. New specification permits grade classes 32/45 and 40/20.
  11. New requirement. MCHW CC 495, Section 3, cl 3.24 Supplier check of chloride content of porous no-fines concrete mix by calculation.
  12. New requirement. MCHW CC 495, Section 3, cl 3.21. Verification by trial of correct water- cement ratio of porous no-fines concrete mix.
  13. New requirement. MCHW CC 495, Section 4, cl 4.26. Contractor to provide BS 8443 Annex D report of stability of foamed concrete designed for use in the scheme.
  14. New requirement. MCHW CC 495, Section 4, cl 4.69. New test for soundness of a sample of foamed concrete placed in a pre-constructed timber test box, plus testing of crushing resistance of foamed concrete at age 24 hours using a BRE impact testing device. 24 hours is minimum age before adding more concrete in lifts of up to 1m. Required after placement of each lift of foamed concrete in the void being infilled.
  15. New requirement. MCHW CC 495, Section 4, cl 4.76. When the soundness of concrete in the above test box is acceptable, the anchor drag test will determine whether the foamed concrete has set within the void being infilled.
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