Section 1 Materials

1.1.1 Tests are to be made on all proposed materials prior to construction. The tests are to be carried out by an independent laboratory which is acceptable to Lloyd’s Register (LR). Appropriate trials on proposed concrete and grout mixes will also be required. The testing is generally to be carried out in accordance with recognised National Codes or Standards, and is to be agreed with LR.

1.1.2 Certificates are to be submitted for all materials before work commences on site.

1.2.2 The cement is to comply with the requirements of these Rules and with recognised National Codes or Standards. High-alumina cement is not to be used.

1.3.1 Cement replacements, such as ground granulated blast furnace slag (g.g.b.f.s), pulverised fuel ash (p.f.a) or silica fume may be combined with Ordinary Portland Cement.

1.3.2 The proportions of the blend and the blended product itself are to comply with recognised National Codes or Standards. In particular circumstances blended proportions outside the range of normal Code requirements may be agreed with LR.

1.3.3 The percentage of silica fume in a blend is to be limited to 10 per cent by weight of cement.

1.4.1 In order to limit potential sulphate attack, the tricalcium aluminate () content of the cement is, in general, to be limited to 8 per cent, but in no case is it to exceed 10 per cent. The minimum content is to be 5 per cent.

1.5.1 Coarse and fine aggregates may be uncrushed and/or crushed natural and/or artificial mineral substances with particle sizes, shapes and other properties which have been accepted for use by testing and experience.

1.5.2 Marine aggregates are acceptable provided that the chloride salt content is at an acceptable level and the aggregate has a sufficiently low shell content. The total chloride content of the concrete mix arising from the aggregate, together with that from any admixtures and from any other source, is not to exceed 0,1 expressed as a percentage relationship between chloride ion and mass of cement in the mix.

1.6.1 Some aggregates may be susceptible to deleterious reaction with alkalis normally present in the cement or from other sources including sea-water; this produces an expansive reaction which can cause cracking and disruption of the concrete.

1.7.1 Lightweight aggregates may be used, but the suitability of the aggregate selected for use is to be demonstrated.

1.8.1 Water is to be clean and free from harmful matter, and is also to comply with National Codes or Standards. Seawater is not to be used as mixing or curing water for any concrete containing reinforcement or pre-stressing tendons.

1.9.1 Air-entraining agents, workability agents and retarding agents may be used. The effects of over and under dosage should be established. Calcium chloride is not to be used or any admixtures containing more than 0,1 per cent chloride ion.

1.10.1 Reinforcement is to comply with an appropriate recognised National Code or Standard. Storage, bending and acceptable welding practices are also to be in accordance with an approved standard agreed with LR.

1.11.1 Pre-stressing tendons are to comply with appropriate recognised National Codes or Standards. Handling and tensioning procedures are also to be agreed. The time periods between installing strands, tensioning and grouting are to be agreed.

1.12.1 Rigid or semi rigid watertight ducting may be used. Suitable procedures are to be developed and approved by LR for ensuring that the ducts are placed correctly, are watertight and kept free of debris and concrete during construction.

1.13.1 Ordinary Portland Cement is preferred. Sea-water is not to be used. Admixtures should be free from products liable to damage the steel or grout itself, such as chlorides, nitrates or sulphides. Expanding agents based on aluminium may be used provided it has been demonstrated to LR’s satisfaction that the particular dose rate does not lead to stress corrosion.

1.13.2 The mix is to have appropriate fluidity and bleed properties. These should be verified by trials. For high strength concrete (>65 MPa) consideration should be given to increasing grout strength above the 40 MPa normally achieved.

1.13.3 Grouting procedures are to be developed and approved by LR. For long tendons and ‘U’ tendons, etc. procedures are to be verified with a prototype trial.