IS 14959 (Part 1) : 2000Method of Test determination of water-soluble and acid-soluble chlorides in mortar and concrete, Part 1: Fresh mortar and concrete
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IS 14959:2000 (Part 1) is the Indian Standard (BIS) for method of test determination of water-soluble and acid-soluble chlorides in mortar and concrete, part 1: fresh mortar and concrete. This standard details the laboratory test methods for determining both water-soluble and acid-soluble chloride content in fresh concrete and mortar samples. The procedures are based on chemical titration and are essential for quality control to prevent reinforcement corrosion and ensure long-term durability.
Method of Test determination of water-soluble and acid-soluble chlorides in mortar and concrete, Part 1: Fresh mortar and concrete
Overview
Status
Current
Usage level
Specialized
Domain
Materials Science — Cement, Concrete, Aggregates and RCC
! Water-soluble chlorides indicate the immediate corrosion risk, while acid-soluble chlorides represent the total chloride content (both free and bound).
! Proper sampling from the structure is critical for a representative result. Samples are often taken as drilled powder at different depths from the concrete surface.
! The results from this test are compared against the permissible limits given in IS 456 (Table 8) to determine compliance and potential for long-term damage.
BS 1881-124:2015BSI - British Standards Institution (UK)
MediumCurrent
Testing concrete - Part 124: Methods for analysis of hardened concrete
Covers acid-soluble and water-soluble chloride determination, but is specified for hardened, powdered concrete samples.
ASTM C1218 / C1218M - 17ASTM International (USA)
HighCurrent
Standard Test Method for Water-Soluble Chloride in Mortar and Concrete
Specifies water-soluble chloride determination with a similar titration method, but for hardened samples with different extraction procedures.
ASTM C1152 / C1152M - 04(2020)ASTM International (USA)
MediumCurrent
Standard Test Method for Acid-Soluble Chloride in Mortar and Concrete
Covers acid-soluble chloride determination for hardened samples but prescribes a different titration technique (Volhard method).
EN 14629:2007CEN - European Committee for Standardization (Europe)
MediumCurrent
Products and systems for the protection and repair of concrete structures - Test methods - Determination of chloride content in hardened concrete
Details the potentiometric titration method for chloride in hardened concrete, aligning with the chemical analysis but not the fresh sample state.
Key Differences
≠IS 14959 Part 1 is explicitly for fresh concrete, whereas the primary international standards (BS 1881-124, ASTM C1218/C1152) are written for hardened, powdered concrete samples.
≠For water-soluble chlorides, the IS code specifies a 20-minute continuous stir for extraction, while ASTM C1218 requires a 24-hour soaking period and BS 1881-124 uses a 24-hour extraction with shaking, reflecting the different sample states.
≠For acid-soluble chlorides, IS 14959 uses direct potentiometric titration, similar to the British/European standard, but ASTM C1152 specifies the Volhard method, which is a back-titration using potassium thiocyanate.
≠The initial sample size in the IS code (approx. 300g for concrete) is much larger because it's a representative mass of the wet mix, whereas standards for hardened concrete use a small (e.g., 5-10g) powdered sample.
Key Similarities
≈The fundamental principle is identical: extracting chloride ions from a concrete or mortar sample into an aqueous solution for quantitative analysis.
≈The use of dilute nitric acid for digestion to determine total (acid-soluble) chlorides is a common method shared between IS 14959, BS 1881-124, and ASTM C1152.
≈Potentiometric titration with silver nitrate (AgNO3) is the specified or a primary method for determining chloride ion concentration in the final solution across IS 14959, BS 1881-124, and ASTM C1218.
≈All standards aim to achieve the same objective: to quantify the chloride content to assess and control the risk of corrosion of steel reinforcement in concrete.
Parameter Comparison
Parameter
IS Value
International
Source
Test Sample State
Fresh mortar and concrete
Hardened, powdered mortar and concrete
BS 1881-124:2015
Water-Soluble Chloride Extraction Time
20 minutes (continuous stirring)
24 hours (soaking)
ASTM C1218 / C1218M - 17
Water-Soluble Chloride Extraction Time
20 minutes (continuous stirring)
24 hours (shaking)
BS 1881-124:2015
Acid-Soluble Titration Method
Direct potentiometric titration
Volhard Method (back-titration)
ASTM C1152 / C1152M - 04(2020)
Water-Soluble Titration Method
Potentiometric titration
Potentiometric titration
ASTM C1218 / C1218M - 17
Acid for Digestion (Acid-Soluble)
Dilute Nitric Acid (HNO3)
Dilute Nitric Acid (HNO3)
BS 1881-124:2015
Typical Sample Mass for Analysis
Approx. 300 g (fresh concrete)
5 g to 10 g (powdered hardened concrete)
BS 1881-124:2015
⚠ Verify details from original standards before use
Key Values5
Quick Reference Values
Sample drying temperature105 ± 5 °C
Sample finenessPassing 150-micron IS Sieve
Minimum sample weight for testing5 g
Titrant normality0.1 N Silver Nitrate (AgNO3)
Indicator for titration5 percent Potassium Chromate (K2CrO4) solution
Key Formulas
Chloride percent by mass = (3.545 * V * N) / W
Tables & Referenced Sections
Key Tables
No tables data
Key Clauses
Clause 4 - Principle
Clause 7 - Sampling and preparation of test specimen
Clause 8 - Procedure for Determination of Water-Soluble Chlorides
Clause 9 - Procedure for Determination of Acid-Soluble Chlorides
What is the difference between this test and Part 1 of IS 14959?+
Part 2 is for hardened concrete and mortar, while Part 1 is for fresh concrete and constituent materials.
Why is it important to test for chlorides in hardened concrete?+
To assess the risk of corrosion of embedded steel reinforcement, which can be caused by chlorides penetrating the concrete from the environment (e.g., de-icing salts, marine spray) or from contaminated materials.
What are the acceptable limits for chloride content?+
This standard only provides the test method. The acceptable limits are defined in design codes like IS 456:2000 (Table 8), which vary depending on whether the concrete is plain, reinforced, or prestressed.
What is the principle of the titration method used?+
It uses Mohr's method, where a chloride solution is titrated against silver nitrate. Silver chloride precipitates, and the endpoint is detected when excess silver nitrate reacts with a potassium chromate indicator to form a reddish-brown silver chromate precipitate.