3.3.5.1 General
(1) The sub-sections below apply to site-mixed concrete, ready-mixed concrete and factory-made concrete.
(2) They refer to the load-bearing and bracing components of non-reinforced, reinforced and prestressed concrete with a close-grained texture. 3.3.5.2 Standards
(1) Recognized international or national standards relating to concrete structures shall be used as a basis for design, calculations, construction, production and execution.
(2) The following standards are recognized for design and calculations:
– EN 1992 (Eurocode No. 2): Design of concrete structures
– DIN 1045-1: Concrete, reinforced and prestressed concrete structures – part 1: Design and construction
– For fatigue verification: CEB FIP Model Code 1990
(3) If other standards or methodologies are used for the design and the calculations of the concrete structures, they shall fulfil at least the safety level of the above-mentioned standards. If not, the safety of
Chapter 3 3.3 Materials IV – Part 2
Page 3-18 GL 2010
the proposed design and calculation methodology shall be demonstrated and shall be agreed with GL. (4) The following standards are recognized for production and construction:
– EN 206: Concrete
– DIN 1045-2: Concrete, reinforced and prestressed concrete structures – part 2: Specifi- cation, properties, production and conformity – EN 10080: Steel for the reinforcement of con-
crete, weldable reinforcing steel
– DIN 488: Reinforcing steels; grades, properties, marking
– EN 10138: Prestressing steels
– DIN 1045-3: Concrete, reinforced and pre- stressed concrete structures – part 3: Execution of structures
– EN 13670: Execution of concrete structures (5) GL shall be notified in good time of the stan- dards intended to be used for design, calculations and construction, and their application shall be coordi- nated with GL.
(6) The materials used during construction, execu- tion and erection shall comply with the standards applied for design and calculations. If materials ac- cording to standards other than those mentioned above are used for construction, their compliance with the design codes shall be verified.
3.3.5.3 Raw materials for concrete
3.3.5.3.1 Cement types
The types of cement shall comply with EN 197 or the respective national standards or regulations applying where the concrete is being used. For national stan- dards, compliance with the standards used for design and calculation shall be verified.
3.3.5.3.2 Concrete aggregate
(1) Aggregates shall comply with EN 12620 or the requirements of the national standards or the regula- tions applying where the concrete is being used. Compliance with the standards used for design and calculation shall be verified.
(2) Aggregates shall not contain harmful constitu- ents in such quantities that the durability of the con- crete is adversely affected or corrosion of the rein- forcing material is initiated.
(3) Aggregate with alkali-sensitive constituents may not be used as a rule.
(4) Maximum grain size and grading curve of the aggregate shall be selected in accordance with EN 206.
3.3.5.3.3 Added water
The added water shall not contain harmful constitu- ents in such quantities as may impair setting, harden- ing and durability of the concrete or may initiate corrosion of the reinforcing material. In Europe, drinking water from public supplies is in general suitable for making concrete.
3.3.5.3.4 Admixtures
(1) Concrete admixtures may be used for concrete and cement mortar only if tests have shown that they neither produce adverse changes in important proper- ties of the concrete nor impair the corrosion protec- tion of the reinforcement. Special suitability tests for the concrete to be made may, in individual cases, be required by GL.
(2) Chlorides, chloride-bearing or other steel- corrosion-promoting materials may not be added to reinforced or prestressed concrete.
3.3.5.3.5 Additives
Additives may only be applied to the concrete mix in such quantities that they neither impair the durability of the concrete nor result in corrosion of the rein- forcement.
3.3.5.4 Building materials
3.3.5.4.1 Concrete
(1) The composition of concrete shall be so chosen that all requirements regarding the properties of the green and the set concrete are met, including consis- tency, bulk density, strength and durability plus pro- tection of the steel reinforcement against corrosion. The composition shall be adjusted to the workability necessary for the construction method adopted. (2) This Guideline is based on the characteristic cylinder compressive strength (28-day strength) fck. It
is defined as the strength figure above which 95 % of the population of all possible strength measurements of the concrete in question may be expected to lie (95 % fractile). This shall be verified with a confi- dence level of 95 %.
V – Part 1 3.3 Materials Chapter 3
GL 2010 Page 3-19
3.3.5.4.2 Concrete-reinforcing steel
(1) This sub-section applies to concrete- reinforcing steel, from coil and mats, used as rein- forcement in concrete structures.
(2) Diameter, surface characteristics, strength properties and marking of concrete-reinforcing steels shall correspond to the relevant standards (EN 10080, DIN 488). If welding is to be carried out on concrete- reinforcing steels, only grades suitable for this may be used (e.g. according to DIN 488, Part 1).
(3) Welding of reinforcing steels is in principle allowable. In this case, the S/N curves of welded reinforcing steel (CEB FIP Model Code 1990) shall be applied in the design calculations and the welding shall be performed in accordance with the standards DIN 4099 or DIN EN ISO 17660 by a workshop approved according to these standards.
3.3.5.4.3 Prestressing steel and prestressing procedure
(1) This sub-section applies to wires, rods and braids that are used as prestressing elements in con- crete structures.
(2) The properties of the prestressing steel shall correspond to the standards mentioned in Section 3.3.5.2 and shall be proved by certificates from the manufacturer. In particular, data and test results con- cerning the composition of the steel, mode of produc- tion, stress-strain characteristic, elastic limit, yield point, tensile strength, fatigue strength and creep limit shall be submitted. This documentation may be re- placed by an approval of the relevant authorities (e.g. European Technical Approval (ETA) or German Technical Approval (“Allgemeine bauaufsichtliche Zulassung”).
(3) For the prestressing procedure (anchors, cou- plings, grout pipes etc.), an approval (e.g. ETA or “Allgemeine bauaufsichtliche Zulassung”) according to the applicable standards is required.
3.3.5.4.4 Grouting mortar for prestressing sys- tems
(1) The grouting mortar is made from cement, water and admixtures/additions, its function being to ensure a good bond between prestressing elements and enclosing body and to protect the enclosed steel against corrosion, by enveloping the elements and filling up all the spaces inside the sheath.
(2) As a rule, only Portland cement shall be used. Drinking water from public supplies is in the great majority of cases suitable for making grouting ce-
ment. Admixtures and additives shall comply with the standards.
3.3.5.4.5 Grout for connections
(1) Grout for connections of precast elements shall fulfil the requirements of the standards on which the calculations are based (e.g. Eurocode 2, in particular the cylindrical compression strength fck).
(2) The DAfStb guideline “Herstellung und Ver- wendung von zementgebundenem Vergussbeton und Vergussmörtel” [3.4] by Deutscher Ausschuss für Stahlbeton (DAfStb) is recommended.
3.3.5.4.6 Steel for embedded steel sections and prestressed high-tensile bolts
(1) Embedded steel sections for connections be- tween tubular steel tower and foundation are normally made from steel according to Section 3.3.2.1.
(2) Prestressed high-tensile bolts shall be used in accordance with the standards. Only bolts in strength classes 8.8 or 10.9 shall be used.
3.3.5.5 Durability of the concrete
(4) In order to produce a concrete of adequate durability, i.e. one which protects the reinforcing steel against corrosion and adequately withstands the ex- ternal and operating conditions to which it is exposed during the anticipated working life of the structure, the following factors shall be taken into considera- tion:
– selection of suitable raw materials that do not contain any harmful constituents which may im- pair the concrete’s durability and cause corrosion of the reinforcing material
– selection of a suitable composition for the con- crete so that it
– meets all the criteria laid down for the prop- erties of green and set concrete,
– can be so poured and compacted that a dense concrete covering layer is formed, – withstands internal influences, and – withstands external influences, e.g. envi-
Chapter 3 3.3 Materials IV – Part 2
Page 3-20 GL 2010
– attacks of a mechanical nature
– mixing, pouring and compacting of the green concrete so that the raw materials are distributed evenly throughout the mixture and do not segre- gate, and a close-grained texture for the concrete is achieved
– curing of the concrete so that in particular the portion near the surface (covering layer) attains the properties to be expected from its composi- tion
(5) Information on defining the environmental conditions for the design can be obtained from e.g. EN 206.
(6) All these factors shall be controlled and veri- fied by the constructor, subcontractor or supplier within their respective zones of responsibility as part of their respective internal surveillance (production control).
IV – Part 1 3.4 Production and Testing Chapter 3
GL 2010 Page 3-21