Special Digest Third editionConcrete in aggressive groundBRE Construction Division BRE is committed to pro. Download Citation on ResearchGate | BRE report – Concrete in aggressive grounds: An introduction to BRE Special Digest 1 | The codes and standards for. The introduction of the edition of BRE Special DIgest 1 (SP1) provides the guidance on concrete in sulfate-bearing ground. The range of exposure.
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However, silica fume can be used in accordance with Clause 5.
Instead, footnotes call for adjustments to be made for section widths of less than mm and greater than mm in particular circumstances. Development of guidance on classification of sulfate-bearing ground for concrete.
Concrete in Aggressive Ground:3rd edition – PDF Free Download
Only in very exceptional circumstances in the UK speccial pH values found below 2. Because this Standard did not cover some tests needed for ground investigation in respect of concrete, it was supplemented in by procedures detailed in BRE Report BR The Design Sulfate Class for the locality may be taken as the aggressove of these adjusted sulfate classes. The reactions that take place when sulfates enter the concrete matrix are complex and contentious.
This applies to any face specual will later be in contact with the ground or groundwater. Assessing the aggressive chemical environment Digst In general, it should be realised that some attack of this sacrificial concrete can be expected. Step 8 Step 6 Determine the sulfate class equivalent to the characteristic value of the total potential sulfate content using columns 1 concrfte 6 of Table C2 on the next page. The permitted relaxations are applied in Table E1 on page 51 which here replaces Table D1.
This reaction product also has a greater solid volume than the original constituents and in some cases can contribute to degradation of the concrete. Method of specifying and guidance diyest the specifier BS EN BRE is a building science centre that generates new knowledge through research. As in the previous cases, the concrete contained carbonatebearing aggregates[1,4—6]. At the time of preparation of SD1: Guidance is given in Section C2. Since the late s, however, deterioration of concrete as a result of the formation of thaumasite has become recognised as a separate form of sulfate attack.
Differing site assessment procedures are given here for natural ground, for brownfield locations that may contain aggressive chemical residues, and pyritic ground. A typical example would be clayey soils with tight fissures and no included sand or silt horizons.
These ball-park limits were converted in in BRE Digest to 2: The effectiveness of integral waterproofing agents in preventing sulfate attack has not yet been established.
B2 Principal types of chemical attack on concrete B2. Recommended test methods for the chemical analysis of aggressive soils are given in Appendix C1. The procedure for taking account of the measured chloride content in this particular circumstance is given in Section C5.
Consequently, a further relaxation beyond that allowed for surface carbonation is permitted in respect of specification of DC Class for aggressive sulfate conditions. This immediately reacts with water to form hydrogen sulfide H2Sa gas that rises into the air space above the sewage. Knowledge of these can be important bearing in mind that magnesium, sodium and potassium sulfates are potentially more problematic than calcium sulfate owing to their high solubilities and different chemical activities, particularly in the case of magnesium sulfate which is notably aggressive to some types of concrete.
Apart brre this, and the need to identify brackish and sea waters, no account is taken of chloride concentration in the procedure for concrete specification in Section D. This measure is not appropriate where the surface of the concrete must remain sound to prevent loss of frictional resistance or settlement eg for spfcial friction piles. The Design Sulfate Class for the location should then be taken as the highest of the sulfate classes derived by the differing procedures.
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The project specification should state clearly whether any APMs are needed that are not shown on the contract drawings and whether any particular types are required or preferred.
D5 Composition of concrete to resist chemical attack D5. Concrete surfaces that are carbonated are digesy prone to this form of attack.
Groundwater samples can be obtained by collecting seepage into a trial pit or borehole. The same phenomenon accounts for the formation of solution features karst in limestone strata.
SD 1 Concrete in aggressive ground. 3rd edition, BRE – Publication Index | NBS
Cement and Concrete Composites, 25 8 — Determination of aggressive carbon dioxide content 38 Part D Specifying concrete for general cast-in-situ use D1 Introduction This part provides guidance on concrete quality aggrdssive any additional protective measures APMs required to provide resistance to chemical attack.
The likelihood of sulfates being present in natural ground depends on the geological strata, the weathering history of those strata and the groundwater flow patterns.
Ground containing excessive amounts of manmade i eg resulting in an acidity of less than pH 2. Sulfates or chlorides in solution may be drawn through the concrete by capillary suction to evaporate at or close to the free surface. However, aggressive presence may well affect the setting of concrete through an inhibition or modification of the hydration of the cement. The potential for this form of attack is taken into account in Table C1 on page 31 when assessing ground containing flowing water for concrete design.
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