Center for By-Products Utilization

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1 Center for By-Products Utilization CHLORIDE ION PENETRATION TEST, CARBONATION DEPTH TEST, AND SALT- SCALING TEST By Tarun R. Naik Report No. CBU REP-566 August 2004 Presented at RILEM meeting, Koriyama, Japan, September Department of Civil Engineering and Mechanics College of Engineering and Applied Science THE UNIVERSITY OF WISCONSIN MILWAUKEE

CBU-2004-18 REP-566 August 2004 Presented at RILEM meeting, Koriyama, Japan, September

2 Chloride Ion Penetration Test [1] This test method (ASTM C 1202) covers the determination of the electrical conductance of concrete to provide a rapid indication of its resistance to the penetration of chloride ions. This test method is applicable to types of concrete where correlations have been established between this test procedure and long-term chloride ponding procedures such as those described in AASHTO T 259. Test Method This test method consists of monitoring the amount of electrical current passed through 2-in (51 - mm) thick slices of 4-in (102 - mm) nominal diameter cores or cylinders during a six-hour period. A potential difference of 60 V DC is maintained across the ends of the specimen, one of which is immersed in sodium chloride solution, the other in a sodium hydroxide solution. The total charge passed, in coulombs, has been found to be related to the resistance of the specimen to chloride ion penetration. Sample preparation and selection depends on the purpose of the test. For evaluation of materials or their proportions, samples may be cores from test slabs or from large diameter cylinders or four-inch (102-mm) diameter cast cylinders. For evaluation of structures, samples may be cores from the structure or four-inch (102-mm) diameter cylinders cast and cured at the field site. 1

This test method is applicable to types of concrete where correlations have been established between this test procedure and long-term chloride ponding procedures such as those described in AASHTO T

3 Significance and Use In most cases the electrical conductance results have shown good correlation with chloride ponding tests, such as AASHTO T 259, on companion slabs cast from the same concrete mixtures. This test method is suitable for evaluation of materials and material proportions for design purposes and research and development. The numerical results (total charge passed, in coulombs) from this test method must be used with caution, especially in applications such as quality control and acceptance testing. The qualitative terms in Table 1 should be used in most cases. Table 1: Chloride Ion Penetrability Based on Charge Passed Charge Passed (coulombs) Chloride Ion Penetrability > 4,000 High 2,000-4,000 Moderate 1,000-2,000 Low 100-1,000 Very Low < 100 Negligible 2

The numerical results (total charge passed, in coulombs) from this test method must be used with caution, especially in applications such as quality control and acceptance testing.

4 Measurement of hardened concrete carbonation depth [2] Aim and Scope The method of testing consists of determining the depth of the carbonated layer on the surface of hardened concrete by means of an indicator. This method can be carried out using specimens made in the laboratory, on specimens taken from completed structures (site specimens), and for testing on site. Tests on laboratory specimens are generally used for comparing the rate of carbonation in concrete specimens with various mixtures, under defined conditions. Tests on site or with site specimens are necessary, in general, to give information on the state of a structure or structural member at a certain moment in time, under the conditions on site. Because of possibly wide scattering of carbonation depths on site and because of the various controlling factors, site tests are not suitable for comparing various concretes by referring only the part tested. In the case of tests using site specimens, the requirements for accuracy of measurement are in general less severe than for laboratory specimens. Carbonation affects various properties of hardened concrete. Primarily, the protection of the reinforcing steel against corrosion decreases, which is originally guaranteed by the highly alkaline pore solution of the cement paste. Climatic conditions leading to the highest rate of carbonation are not identical with those which accelerate corrosion of 3

Tests on laboratory specimens are generally used for comparing the rate of carbonation in concrete specimens with various mixtures, under defined conditions.

5 steel. Other concrete properties, such as strength, permeability, and resistance to some chemical and physical attacks, as well as shrinkage, are also affected by carbonation. This recommendation is aimed at improving the comparability of carbonation tests. It is not aimed at laying down optimal test conditions for special testing problems. Definition Carbon dioxide which penetrates the surface of concrete can react with alkaline components in the cement paste, mainly Ca(OH) 2. This process (carbonation) leads to a reduction of the ph-value of the pore solution to less than nine. The depth of the carbonated surface layer is called the depth of carbonation d k. The reduction of the ph-value can be made visible by the color change of a suitable indicator. Test Materials A solution of one percent of phenolphthalein in 70 % ethyl alcohol is suitable for determining the depth of carbonation. Phenolphthalein turns non-carbonated concrete red, and remains colorless in carbonated concrete. Specimens: type, making, curing, and storage Concrete prisms with a cross-section of 100 mm x 100 mm that can be split into lengths of roughly 50 mm, for each date of testing, are suitable. For mortar, prisms 40 mm x 40 4

Definition Carbon dioxide which penetrates the surface of concrete can react with alkaline components in the cement paste, mainly Ca(OH) 2.

6 mm x 160 mm are recommended from which a slice of roughly 20 mm is split off at each date of testing. In no case shall the shortest dimension of the prism be less than three times maximum aggregate size. Climatic conditions of storage (relative humidity, amount of CO 2 concentration, etc.) must be precisely defined. Specimens may be stored indoors or out of doors. For indoor storage roughly 0.03 percent CO 2 concentration, a temperature of 20 o C, and a relative humidity of 65 % are recommended. Out of doors, storage under cover (protected against rain) or without cover must be differentiated. Salt-Scaling Test [3] Scope This test method (ASTM C 672) covers the determination of the resistance to scaling of a horizontal concrete surface exposed to freezing and thawing cycles in the presence of deicing chemicals. It is intended for use in evaluating this surface resistance qualitatively by visual examination. Significance and Use This test method can be used to evaluate the effect of mixture proportioning, surface treatment, curing, or other variables on resistance to scaling. This test method is not intended to be used in determining the durability of aggregates or other ingredients of the concrete. 5

) must be precisely defined. Specimens may be stored indoors or out of doors. For indoor storage roughly 0.

7 No relationship has been established between the frost immunity of specimens cut from hardened concrete and specimens prepared in the laboratory. Proportioning and Mixing The air content, cement factor, slump, water-cementitious materials ratio, and other characteristics of the concrete and its ingredients shall be those appropriate for the purposes for which the tests are to be made. Concrete with the following characteristics has been found useful for the purposes for which this test method is generally used, such as evaluation of a surface treatment for prevention of scaling: (a) non-air-entrained; (b) cement content, 335 ± 5 kg/m 3 (565 ± 10 lb/yd 3 ); (c) slump, 75 ± 15 mm (3 ± 0.5 in.); and (d) durable aggregate of 25-mm (1-in.) maximum size. If air-entrained concrete is to be used for comparative purposes, it shall have the same proportions as that with which it is being compared and the air content shall be 6 ± 1 % Specimens Specimens shall have a surface area of at least m 2 (72 in. 2 ) and be at least 75 mm (3.0 in.) in depth. At least two duplicate specimens for each combination of variables to 6

purposes for which the tests are to be made.

8 be tested shall be made. Curing For all concretes, remove the specimens from moist storage at the age of 14 days and store in air for 14 days at 23 ± 2 o C (73.5 ± 3.5 o F) and 45 to 55 % relative humidity. Procedure After completion of moist and air curing: Cover the top surface of specimens with 6 mm (1/4 in.) of a solution of calcium chloride and water, having a concentration such that each 100 ml of solution contains 4 g of anhydrous calcium chloride. Place specimens in a freezing environment for 16 to 18 hour. At the end of this time remove them from the freezer and place them in laboratory air at 23 ± 2 o C (73.5 ± 3.5 o F) and relative humidity of 45 to 55 % for 6 to 8 hour. Add water between each cycle as necessary to maintain the proper depth of the chloride solution. Repeat this cycle daily, flushing off the surface thoroughly at the end of each 5 cycles. After making visual examination, totally replace the solution and continue the test. Either keep specimens frozen during any interruption in the daily cycling or maintain them in a damp condition after removal of solution and flushing surfaces. 7

) of a solution of calcium chloride and water, having a concentration such that each 100 ml of solution contains 4 g of anhydrous calcium chloride.

9 References 1. Annual book of ASTM Standards, 2003, ASTM C 1202 Standard Test Method for Electrical Indication of Concrete's Ability to Resist Chloride Ion Penetration, Vol , pp Measurement of hardened concrete carbonation depth, November - December 1988, Materials and Structures, Vol. 21, No. 126, pp Annual book of ASTM Standards, 2003, ASTM C 672 Standard Test Method for Scaling Resistance of Concrete Surfaces Exposed to Deicing Chemicals, Vol , pp

Resist Chloride Ion Penetration, Vol. 04.02, pp. 650-655. 2.

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