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Advertising supplement provided by Portland Cement Association

by Jennifer Grover Prokopy

Inspection

As the saying goes, “don’t expect what you don’t inspect.” This applies directly to masonry inspections, which are governed by the Building Code Requirements for Masonry (ACI 530/ASCE-5/TMS 402). The Code requires different levels of minimum inspection depending on the building use and design procedures. Any agency providing testing and inspection services must be accredited under ASTM C1093, the Standard Practice for Accreditation of Testing Agencies for Unit Masonry.

Inspections of volume proportion in masonry mortars provide instant results, so contractors can make changes to the mix on-site and avoid costly problems down the road. An inspector should monitor the proportions of sand to the cementitious material, whether it is mortar cement, masonry cement or a portland cement-lime mixture. Water monitoring will be supervised by the mason, who will adjust water levels to produce the desired level of workability.

It is neither necessary nor desirable to limit water content of mortars by specification or inspection as with concrete. A more flowable mortar with higher water content typically provides improved bond and performance over a stiffer mortar with lower water content (made with the same materials). Inspectors also should be familiar with hot and cold weather requirements for masonry.

Testing

Masonry mortar QA programs require testing to perform two functions:
to qualify mortar materials, and to perform quality control of mortar. Understanding the difference between these two functions, and the variety of tests performed to achieve each function, will reduce mistakes commonly made in the field.

Qualification of masonry mortar materials must be established prior to construction. Two different aproaches are allowed by the Standard Specification for Mortar for Unit Masonry (ASTM C270). One qualifies the materials under property specifications; the other qualifies the materials under proportion specifications. If the property specification method is not chosen, the proportion specification method applies.

For field QC of mortar, inspection is typically the most timely and effective quality control procedure. Observation of batching and mixing procedures provides real time information and immediate corrective action. Requiring use of a volumetric measuring device can improve accuracy of sand proportioning. If desired, field testing as outlined by the Standard Test Method for Preconstruction and Construction Evaluation of Mortars for Plain and Reinforced Unit Masonry (ASTM C780) can be used. Some of the prescribed tests measure properties of plastic mortar, but the most effective and reliable tests measure the aggregate ratio and water content of mixed mortar, providing an accurate evaluation of site-proportioned mortar materials.
Misconceptions about the appropriate use and value of ASTM C270 and ASTM C780 cause the most common errors in field testing of mortars, as explained below in greater detail.