Durability Testing

Air Void Analysis of Hardened Concrete

Hardened concrete is cut and polished per ASTM C457. Samples are observed under a microscope and properties of the air void system are identified. Total air content, voids/inch, specific surface area, etc. are determined. These values are useful in determining potential freeze-thaw resistance, issues with consolidation, etc.

Resistance of Concrete Beams to Rapid Freezing and Thawing

Concrete prisms are exposed to 300 cycles of rapid freezing and thawing. The fundamental transverse frequency is determined at 30 cycle intervals, and this is used to determine the durability factor rating (out of 100).

Abrasion Resistance of Horizontal Concrete Surfaces

A concrete surface is exposed to a rotating abrasive surface. The type and time is dependent upon the method selected (A, B, or C). Method C is selected most often, and consists of a rotating set of ball bearings applying constant abrasion to the surface for 20 minutes. Depth of abrasion is reported.

Length Change of Mortar Bars Exposed to a Sulfate Solution

Mortar bars are cast using the materials of interest. Bars are subsequently immersed in a sulfate solution and intermittent length comparitor readings are performed to determine the effects of sulfate exposure on the mortar.

Alkali-Carbonate Reaction (ACR) of Concrete Beams – 1 to 2 Year Test

Concrete prisms are cast using the aggregate of interest, along with other materials of known ACR properties. Prisms are kept at standard moist room conditions for a minimum period of 1 year. Length change readings are used to assess the long-term effects of ACR on the concrete.

Acid-Soluble Chloride Content of Powdered Cement, Pulverized Mortar, or Pulverized Concrete

A sample of powdered material is extracted with nitric acid and titrated against a silver nitrate solution to produce the acid-soluble chloride content of the material.

Water-Soluble Chloride Content of Powdered Cement, Pulverized Mortar, or Pulverized Concrete

A sample of powdered material is extracted with boiling water and titrated against a silver nitrate solution to produce the water-soluble chloride content of the material.

Alkali-Silica Reaction (ASR) of Mortar Bars

Mortar bars are immersed in a strong alkali solution for 2-4 weeks. Length comparitor measurements are taken to determine the effects of ASR.

Alkali-Silica Reaction (ASR) of Concrete Beams – 1 to 2 Year Test

Concrete prisms are cast using the aggregate of interest, along with other materials of known ASR properties. Prisms are kept at peak relative humidty, at a temperature of 100F, for a minimum of 1 year. Length change measurements are used to assess the long-term effects of ASR on the concrete.

Water-Soluble Chloride Content of Aggregates by Soxhlet Extraction Method

Provides the water-soluble chloride content of an aggregate. Chloride is extracted through multiple exposure cycles of boiling water condensation in the Soxhlet Extraction Apparatus.

Apparent Chloride Diffusion Coeffecient of Cementitious Mixtures by Bulk Diffusion

A sample is cast or cored from a representative mixture to a depth of at least 3 inches (larger preferred). Samples are laboratory cured for 28 days, cut, sealed per ASTM C1202, then immersed in a calcium hydroxed water bath. A minimum of 35 days of immersion is performed, after which profiles are ground of varying depths. This material is then evaluated for chloride content per ASTM C1152, and a depth vs chloride content graph is used to calculate the chloride diffusion coefficient.

Alkali-Silica Reaction (ASR) of Mortar Bars Made with SCM

Mortar bars are immersed in a strong alkali solution for 2-4 weeks. Length comparitor measurements are taken to determine the effects of ASR.

Rate of Absorption of Water by Hydraulic-Cement Concretes

Standard 4″ diameter x 2″ length specimens are obtained by molding or coring. Specimens are placed in a 50°C 80%RH environment for 3 days. Specimens are then placed in a sealed container for at least 15 days. Specimen sides are sealed, and placed in the absorption tank, and the rate of absorption is measured by recording the increase in specimen mass over time.

Surface Indication of Concrete’s Ability to Resist Chloride Ion Penetration

Samples are cast or cored (4″x8″ or 6″x12″) and the resistivity across the specimens are measured by use of a 4-pin Wenner probe array. An alternating current potential difference is applied at the out pins by the apparatus, and the resultant potential difference across the two inner pins is measured. The current used and the resulting potential difference, along with sample area, are used to calculate the resistivity of the concrete. This has been found to relate to the resistance of the concrete to resist chloride ion penetration.