A research program was developed to investigate relative properties of three mortars containing lime-replacement additives compared to the properties of four traditional portland cement-lime mortars used in masonry construction. Plastic and hardened properties were determined using standard ASTM test methods. The test program indicates that, although the three lime-replacement mortars have comparable compressive strengths to portland cement-lime mortars, they have significantly different water retention and air content percentages and, as tested, the lime-replacement mortars do not meet specification requirements of either ASTM or ICBO. In addition, masonry walls constructed with the three lime-replacement mortars studied in this program were less resistant to water penetration than walls constructed with portland cement-lime mortars. It is suggested that ASTM specifications and test methods currently under development consider the essential properties of water retention, air content, and water penetration resistance in addition to compressive strength for acceptance of lime-replacement materials.
An investigation was conducted to evaluate the movement of water vapor and liquid water (permeance from driving rain), and their effect on the transient moisture characteristics exhibited by single-wythe residential clay masonry exterior load-bearing wall systems. The wall system evaluated was constructed of standard 6 in. hollow (ASTM C 652) units and used a variety of insulation configurations. These wall systems were evaluated for water penetration performance using ASTM E 514 water penetration tests. The transient thermal and vapor transmission characteristics of each configuration were also evaluated using a one-dimensional finite difference analysis (the MOIST analysis program).
The results of this investigation indicate that if properly designed and constructed, the wall system provides excellent resistance to wind-driven rain. However, the investigation also indicated that interstitial condensation may occur in the insulation and interior sheathing layers if the system is not properly designed for the prevailing climate.
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