Carbon Capture

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.

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.

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.

Effects of Chemical Admixtures on Corrosion of Embedded Steel Reinforcement in Concrete Exposed to Chloride Environments

Control specimens and specimens with admixture are cast with reinforcing bars placed per ASTM G109. A minimum of three replicates are tested in each condition. A salt solution is ponded on top of each specimen, and a high impedance voltmeter is used to measure the voltage across the resistor over time. At the same time, the corrosion potential is measured against a reference electrode placed in the salt solution per ASTM C876. Finally, at the conclusion of testing, chloride content is determined per ASTM C1152 for the control and the test specimens.

Calcium Oxychloride in Cement Pastes Exposed to Deicing Salts

Cement paste is ground to a powder and exposed to a 20% by mass calcium chloride salt solution. The powder is tested in a Low-Temperature Differential Scanning Calorimetry (DSC) machine, and the heat required to change the sample temperature is recorded as a function of the temperature throughout the test. Calcium oxychloride is determined by comparing the heat released, with the heat released from the phase change of pure calcium oxychloride.