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RE: corrosiveness of foundation soils[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: seaint(--nospam--at)seaint.org
- Subject: RE: corrosiveness of foundation soils
- From: "Collier, Randy" <rhcollier(--nospam--at)winkinc.com>
- Date: Tue, 21 Feb 2006 11:57:39 -0600
In regard to ASTM standards:
ASTM C 227, Potential Alkali Reactivity of Cement-Aggregate Combinations (Mortar-Bar Method)
ASTM C 295, Petrographic Examination of Aggregates for Concrete
ASTM C 1260, Potential Alkali Reactivity of Aggregates (Mortar Bar Method)
ASTM C 856, Petrographic Examination of Hardened Concrete
If you are evaluating an existing concrete foundation, for instance, the quality of the original installation has an affect on the durability of the concrete, such as its resistance to time-dependent stresses and strains induced by creep and shrinkage of the concrete. These strains and accompanying stresses are influenced by the age of loading, initial moisture content of the concrete, ambient relative humidity, volume-to-surface ratios, slump of the fresh concrete, and temperature of the concrete at time of pour. A materials testing laboratory can be contracted to obtain concrete core samples for the determination of the compressive strength, void ratio, and chloride content of the concrete. Concrete cores are removed from the area in question for examination of the reinforcing steel, determination of actual compressive strength of the concrete, laboratory sampling for chloride contents, and petrographic examination of the concrete. Petrographic examination will determine the quality of the concrete paste, the stability of the aggregates, the presence of entrained air, and the extent of any damage due to thermal cycles, or chemical attack. For example, if the concrete contains more than 1.2 total pounds of chloride per cubic yard (or 0.3% by weight of cement), it has sufficient chloride to enable electrochemical corrosion of the reinforcing steel, thus reducing the strength of the concrete.
Hope this helps,
Randall H. Collier, P.E.
Subject: corrosiveness of foundation soils
What is the limitation of Chloride content (ppm), where section 1904.4.2 and Table 19-A-2 need to be enforced? Is there any ASTM standard?
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