SYMPOSIA PAPER Published: 01 January 1990

The Development of Ready Mixed Mortar in the United States


The introduction of Ready-Mixed or Extended-Life Mortar to the masonry industry in the United States in the early 1980's prompted the American Society for Testing and Materials to initiate development of a specification for Ready-Mixed Mortar. The development of this specification was under ASTM Committee C12, on Mortars, and Sub- Committee C12.03, on Specifications. The Sub-Committee commissioned a task group, designated C12.03.7, to develop the specification. The authors of this paper are some of the members of that task group. The data presented is a compilation of information that was submitted by members of the task group in evaluation of ready-mixed mortar. Both laboratory- and field-developed data have been submitted.

Ready-Mixed Mortar is best defined as “Mortar consisting of cementitious materials, aggregate water, and set control admixtures which are measured and mixed at a central location using weight or volume control equipment. This mortar is delivered to a construction site and shall have a workability period in excess of 2-1/2 hours.”.

The data that is presented in this paper represents testing of Ready-Mixed Mortar for basic physical properties such as compressive strength, air content, water retention, and workability. Additional properties such as bond strength of ready-mix mortars to masonry units, bond strength of ready mixed mortar to steel, water permeance, and compressive strength of masonry prisms, employing ready-mixed mortar have also been examined.

Author Information

Gates, RE
Nelson, RL
Pistilli, MF
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Developed by Committee: C12
Pages: 123–142
DOI: 10.1520/STP24978S
ISBN-EB: 978-0-8031-5124-6
ISBN-13: 978-0-8031-1453-1