The first steps of this lesson
Step 1: Which Mortar Goes Where
2025 CRC R606.2.8 says mortar meets either the proportion specifications of Table R606.2.8 or the property specifications of ASTM C270, and the type depends on the job. Mortar for masonry foundation walls built to Tables R404.1.2.1(1) through R404.1.2.1(4) is Type M or S (R606.2.8.1). Mortar for masonry that serves as the lateral force-resisting system is Type M, S or N in Seismic Design Categories A, B and C (R606.2.8.2), but Type M or S portland cement-lime or mortar cement in D0, D1 and D2 (R606.2.8.3). R606.12.3.4 adds that Type N mortar or masonry cement shall not be part of the lateral force-resisting system in the higher categories. Mortar for adhered masonry veneer is ASTM C270 Type S or N, or latex-modified mortar per ANSI A118.4 (R606.2.11).
Step 2: Read the Cement-Lime Rows of Table R606.2.8
For cement-lime mortar, every type uses 1 part portland or blended cement by volume. The hydrated lime or lime putty changes with the type: Type M is 1/4 part, Type S is over 1/4 to 1/2 part, Type N is over 1/2 to 1 1/4 parts, and Type O is over 1 1/4 to 2 1/2 parts. The aggregate is damp, loose sand, not less than 2 1/4 and not more than 3 times the sum of the separate volumes of the lime and the cement. The same table also lists mortar cement and masonry cement mixes, where the cement type (M, S, N or O) is the type of the mortar.
The remaining 3 steps, the worked example and the quiz are in the course. This is a preview. The full lesson, with the step-by-step explanations, a worked example and a quick-check quiz, is inside the classroom.
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