BS 6349-1-4:2021 pdf free download – Maritime works Part 1-4: General一Code of practice for materials.
Temporary works should be simple and capable of rapid erection during tidal access, and should be strong enough to protect immature concrete and resist high temporary loadings in adverse weather.
The shape of concrete structures and members should be such that they can be formed by simple formwork, which can be easily fixed and is grout-tight, rigid and strong. Complicated shapes should not be used unless unavoidable. Thin cross-sections, in which the cover to reinforcement is sensitive to the accuracy of steel fixing, should not be used unless unavoidable.
Steel reinforcement should be carefully detailed such that it can be rapidly and accurately fixed while having adequate rigidity to resist displacement during placing and compaction of the concrete. Detailing of the reinforcement should be in accordance with BS EN 199 2-1-1 and BS 8666. Due allowance should be made to include practical tolerances for the positioning of reinforcement, especially in difficult site environments.
Structural members and joint spacing should be designed to limit early thermal cracking, and/or steel reinforcement provided in order to control the size and spacing of cracks.
NOTE 1 Thick sections and massive concrete structures are at risk of early-age thermal cracking. Further guidance is given in CJRIA C766 [i].
NOTE 2 Further guidance on construction considerations is given in CIRIA C674 [2]. Additional information on execution of construction is given in BS EN 13670.
6 Durability of concrete structures
The following general factors should be taken into account for the assessment of durability.
a) Design for durability of concrete in maritime works (which can include elements of buildings, bridges or tunnels in coastal locations) is dependent upon the recognition of the specific exposure conditions that affect the various elements of a structure, both macro and microclimate and the adoption of appropriate design, detailing, materials and workmanship to suit these conditions. The specification of the concrete materials and details, such as location of construction joints and cover to reinforcement or prestressing steel (if any), is an integral part of the design process. Structural design and detailing should be undertaken in parallel to the design and selection of materials and details, such as cover, relating to durability
b) The maritime environment can be very aggressive to concrete in terms of physical weathering, abrasion and chemical attack. Chloride-induced corrosion can also damage embedded metal or reinforcement. The assessment of durability in conjunction with maintenance strategy should be a fundamental part of the design process.
c) The durability of correctly placed and compacted reinforced concrete is mainly due to the cover to the reinforcement and the quality of the concrete; the quality is primarily governed by the water/cement ratio, type of cementitious materials and, to a lesser extent, the cement content. Whilst the concrete grade has traditionally been used as an indicator of quality the strength of the concrete, and especially that measured at 28 days, is not a reliable indicator of durability performance.
d) Durability is not in itself a limit state, but is the means by which the serviceability and structural limit states are maintained for the lifetime of the structure. Being inherently time-related, design for durability is directly related to the intended operational life and maintenance strategy for the structure.