This guideline outlines standardized testing procedures for assessing the chemical durability of silicate and resin-based mortars. It details specimen preparation, conditioning, and evaluation of mechanical and physical properties including strength, absorption, and resistance to chemical exposure. The standard is vital for professionals verifying mortar performance in chemically aggressive environments.
Overview
This guideline outlines standardized testing procedures for assessing the chemical durability of silicate and resin-based mortars. It details specimen preparation, conditioning, and evaluation of mechanical and physical properties including strength, absorption, and resistance to chemical exposure. The standard is vital for professionals verifying mortar performance in chemically aggressive environments.
Audience
Contents
Structure
This section defines the test methods for chemical resistant mortars of silicate and resin types, including tests for working and setting times, tensile, flexural, and compressive strengths, bond strength, absorption, porosity, and chemical resistance. It also details specimen preparation, calculations, and rounding rules to standardize results.
Describes the essential apparatus for conducting tests, including specifications for containers like wide-mouth glass jars with inert caps or Erlenmeyer flasks with reflux condensers, conditioned storage of materials at controlled temperature for consistent testing, and apparatus suitability.
Defines the procedures for measuring mortar working time and setting time using Vicat needle penetration tests, including sample handling, specified needle dimensions, penetration limits, and testing surface requirements.
Details preparation of 50 mm cubic specimens with emphasis on mould treatment, mortar placement, compaction, air entrapment elimination, and finishing to ensure uniform density and dimensions.
Outlines the procedure to measure flexural strength, including formula application, specimen rejection criteria for defects or outliers, minimum specimen count requirements, and calculation of average strength.
Explains the methodology for compressive strength evaluation, including loading rates, specimen preparation, reporting standards, and quality control measures to ensure valid and consistent results.
Covers the assembly and curing of tile specimens arranged perpendicularly with controlled joint thickness, detailing drying, mortar application, block setup, and conditioning periods for accurate testing.
Provides formulas and testing steps to calculate absorption percentage and apparent porosity using water or toluene saturation techniques, alongside specimen handling and reporting guidelines.
Describes immersion testing of specimens in chemical solutions, inspection schedules, weight measurement precision, criteria for retesting, and interpretation of results to assess mortar durability.
Lists pertinent ASTM standards related to mortar testing, including working and setting times, strength tests, absorption, and chemical resistance, providing a framework for internationally harmonized testing.
Frequently Asked
For silicate mortars, mix at least 1.5 kg according to manufacturer instructions (adjust if density exceeds 3), prepare six specimens, and keep them in moulds for 24 hours. After 48 to 60 hours, immerse the specimens in a 20% hydrochloric acid solution for 60 minutes, then blot dry. Resin mortars are mixed per manufacturer guidelines, moulded fully to avoid air pockets, finished flush with the mould surface, and left in the mould for at least 48 hours until set to allow safe demoulding. These procedures ensure consistent specimen quality for testing.
Six cube specimens should be tested after the specified curing period, applying load uniformly on specimen faces at a rate of 350 kg/cm² per minute without packing between platens. Faulty cubes must be discarded, and if any value deviates by more than 15% from the average or fewer than four valid results remain, tests must be repeated. Compressive strength is calculated by dividing the crushing load by the average cross-sectional area and expressed in kg/cm². Initial and final strengths are reported clearly, often with graphical representations, ensuring standardized and reliable data.
Specimens and materials must be stored at 27°C ± 2°C for a minimum of 16 hours before testing, maintaining relative humidity within 65% ± 5%. Specimens should be exposed on all sides to air and protected from water contact throughout the aging period. These conditions stabilize moisture content and temperature, ensuring consistent and reproducible test outcomes.
The standard employs a 20% by weight hydrochloric acid solution as the primary immersion medium to assess chemical resistance. Silicate mortar specimens are cured for 48 to 60 hours, then fully immersed in this solution for 60 minutes. After removal and blotting dry, specimens are aged for seven days at 27°C ± 2°C with relative humidity not exceeding 90%, ensuring air circulation and protection from water contact. This method provides a rapid and relevant evaluation of mortar durability under chemical exposure.
After preparation and acid immersion (for silicate mortars), specimens are air-aged for seven days at 27 ± 2°C. They are dried to constant weight (D), saturated with water or toluene, and weighed saturated (W). Absorption percentage is calculated as ((W - D) / D) × 100. Apparent porosity is similarly computed considering the volume and specific gravity of the saturating liquid. Results are averaged over six specimens, with detailed reporting including mortar type, specimen age, failure type, and bond strength, following the standard's methodology.
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