ASTM C1506
Understanding ASTM C1506 Test Method for Water Retention of Hydraulic Cement-Based Mortars and Plasters
The ASTM C1506 test method is designed to evaluate the water retention capacity of hydraulic cement-based mortars and plasters. This procedure is crucial for determining the ability of these materials to retain water when subjected to suction, providing valuable information for both compliance with specifications and comparative analysis of different formulations.
Test Method Summary
The test begins by measuring the initial flow of the mortar or plaster, followed by exposing the sample to a controlled vacuum suction for 60 seconds. After this period, the flow of the mortar or plaster is measured again. The water retention capacity is then calculated as a percentage, derived from the final flow divided by the initial flow.
Significance and Application
This method is significant as it evaluates the mortar's or plaster's ability to retain water under suction, an essential property for practical applications. However, it's important to note that the results obtained might not directly correlate with real-world conditions, especially when different masonry units or plaster layers are involved.
Equipment and Conditions
The test requires specific equipment including a tamper, flow table, straightedge, mixing apparatus, and a filtration assembly comprising a perforated dish, funnel, vacuum flask, and a controlled vacuum source. The testing environment should align with the standard laboratory temperatures and humidity as detailed in Specification C 511.
Material Preparation and Testing Procedure
Mortar or plaster for the test should be prepared according to its specified composition or as described in Practice C 305. The initial setup involves ensuring an airtight seal in the apparatus and setting the vacuum to the correct level. The initial and post-suction flows of the mortar or plaster are determined using Test Method C 1437, with specific attention to the procedure for filling the perforated dish and leveling the material.
Calculation and Reporting
The water retention value is calculated as the post-suction flow divided by the initial flow, multiplied by 100. This value is reported to the nearest 1%.
Additional Considerations
It's essential to ensure that all tools and materials conform to the specified ASTM standards and to follow the safety guidelines outlined in the Manual of Cement Testing. Users should also stay updated with any changes or revisions in ASTM standards that could impact this test method.
This comprehensive procedure provides a standardized approach to assessing the water retention capabilities of mortars and plasters, crucial for quality control and specification compliance in the construction industry.