Masonry mortar samples removed from masonry evidencing distress may be petrographically and chemically analyzed for composition. The success in reconstructing the original mortar composition depends upon the method of analysis, the availability of the parent materials or proper assumptions regarding their composition, and considerations during calculation. This report highlights various considerations for any analysis of mortar composition.
Grout for reinforced masonry is reviewed through national product specifications and national masonry standards and codes. The role of grout and the factors affecting grout performance lead into a review of ASTM Specification for Mortar and Grout for Reinforced Masonry (C 476-71). A critical review of the specification shows that provisions for grout design, materials, and testing are deficient or nonexistent.
Past and present research on grout for reinforced masonry was reviewed and found deficient. Early research allowed measuring the bond of grout to reinforcing steel. Material changes warrant further testing. Recent grouted masonry testing shows grout compressive strength per se is a poor indicator of the interaction of grout in masonry. Research areas deemed essential include grout mix design, grout placement, and grout physical properties of equal or greater significance than compressive strength.
Efflorescence of masonry construction is a natural occurrence when masonry is constructed in other than under normal conditions. Early age efflorescence may occur shortly after construction has been completed; late age efflorescence may occur if design and construction considerations and building maintenance are not properly attended. Efflorescence, once understood, is deemed beneficial toward identifying problems associated with building performance and indicating corrective action to be taken to remedy the situation.
An efflorescence test method for masonry mortars has been developed. The method is considered beneficial for isolating contributors toward efflorescence, be it adverse exposure conditions, cement retarders, or contaminated individual materials. The interpretation of test results allows isolation of contributing factors and remedial action. Practically, testing of masonry mortars will not guarantee that efflorescence will not appear on the surface of a structure.
Strength specifications and test methods over the past 75 years of cement testing are reviewed. Early strength specification ranges and limits, requiring tensile strength tests of neat cement paste and mortar briquets, have evolved into compressive strength specifications, using mortars prepared and tested in accordance with detailed test methods. Though present strength specifications appear adequate, new cementitious materials and research test methods will, no doubt, produce a need for new test methods and specifications, which will include other considerations, such as uniformity.
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