Masonry Magazine February 1994 Page. 44
Field test procedures for mortar should require companion information from preconstruction testing, laboratory testing, other field test procedures, along with a detailed record of test conditions for a meaningful interpretation of results. The purpose of field testing and the potential problem of interpreting results should be carefully considered when selecting which tests to conduct. For example, if control of batching is the purpose of specifying ASTM C780 testing, the aggregate ratio test offers a more direct measure of mortar proportions than does the compressive strength method. For the designer seeking data representative of in-place masonry, the most effective procedures are masonry assembly tests such as ASTM E447, the Standard Method for Compressive Strength of Masonry Prisms. These assembly tests indicate the interaction between mortar and unit, quality of workmanship, mortar consistency, and numerous other characteristics of the masonry.
When examining mortar field compressive strength test results, the responsible authority should remember that: while these results can be used to evaluate uniformity of mortar production, they are not required to meet the minimum compressive strengths of the property specifications of ASTM C270. Such field test results can be expected to be lower and more variable than laboratory test results. Furthermore, field determined compressive strength test results of mortar do not correlate well with the structural properties of the in-place masonry.
If compressive strength test results vary significantly during construction from the values established during preconstruction testing, the cause(s) of that variance must be established before any corrective action can be taken. The quality of mortar materials can be verified by repeating laboratory tests of mortar materials. Batching control may be investigated by running aggregate ratio tests or inspection of batching procedures. Information on the consistency of mortar and other test conditions can be evaluated from the test report. Only a proper identification of the cause(s) can lead to a determination as to which corrective measures, if any, may be appropriate.
Related Publications
Readers of this publication may also be interested in the following publications available for purchase from the Portland Cement Association. A complete listing of PCA publications is given in the free PCA Catalog (MS254G). To order, write or call Order Processing, Portland Cement Association, 5420 Old Orchard Road, Skokie, Illinois 60077-1083, phone 708/966-6200.
A Homeowner's Guide to Building with Concrete, Brick, and Stone, SP038H
Water Penetration Tests of Masonry Walls, IS219M
Building Weather-Resistant Masonry Walls, IS220M
Concrete Masonry Handbook, EB008M
Mortars for Masonry Walls, IS040M
Masonry Cement Mortars, IS181M
SpecData: Masonry Cement, IS238M
Masonry Cement: Beauty to Last a Lifetime, PA163M
Recommended Practices for Laying Concrete Block, PA043M
Masonry Cement Mortars - A Laboratory Investigation, RD095T
Air Content and Water Penetration of Masonry Walls, IS191M
Selecting and Specifying Mortar and Grout for Unit Masonry, IS275M
Trowel Tips: Efflorescence, IS239M
Trowel Tips: Tuckpointing, IS240M
Trowel Tips: Mortar Sand, IS 241M
CAUTION: Contact with wet (unhardened) concrete, mortar, cement, or cement mixtures can cause SKIN IRRITATION, SEVERE CHEMICAL BURNS, or SERIOUS EYE DAMAGE. Wear waterproof gloves, a long-sleeved shirt, full-length trousers, and proper eye protection when working with these materials. If you have to stand in wet concrete, use waterproof boots that are high enough to keep concrete from flowing into them. Wash wet concrete, mortar, cement, or cement mixtures from your skin immediately after contact. Indirect contact through clothing can be as serious as direct contact, so promptly rinse out wet concrete, mortar, cement, or cement mixtures from clothing. Seek immediate medical attention if you have persistent or severe discomfort.
This publication is intended SOLELY for use by PROFESSIONAL PERSONNEL who are competent to evaluate the significance and limitations of the information provided herein, and who will accept total responsibility for the application of this information. The Portland Cement Association DISCLAIMS any and all RESPONSIBILITY and LIABILITY for the accuracy of and the application of the information contained in this publication to the full extent permitted by law.
Portland Cement Association 5420 Old Orchard Road, Skokie, Illinois 60077-1083
An organization of cement manufacturers to improve and extend the uses of portland cement and concrete through market development, engineering, research, education, and public affairs work.