IWR (Integral Water Repellent Mortar)

Reduce Water Penetration and Efflorescence of Masonry Mortar Joints

Standard (IW-01) and Color (IW-05)


SPEC MIX Integral Water Repellent (IWR) mortar is specially formulated to reduce water penetration, shrinkage and efflorescence of masonry mortar joints. By incorporating a proprietary, dry polymeric integral water repellent admixture during the SPEC MIX manufacturing process, the designer, specifier, owner and contractor are assured the mortar on their project will repel moisture, while maintaining optimal workability and flexural bond strength. When using ASTM C 1357 “Test Method for Evaluating Masonry Bond Strength” to compare the flexural bond strength of SPEC MIX IWR Mortar to the same reference mortar mixed with the leading liquid admixture, the SPEC MIX IWR mortar demonstrated a 46 percent increase in bond strength.

SPEC MIX® Integral Water Repellent IWR Mortar is a dry, preblended mortar mix that is produced using either Portland cement and hydrated lime, mortar cement or masonry cement with dried masonry sand and water a proprietary repellent admixture formulated for water repellency, superior bond, water retention and board life. Available in Types M, S and N, each meets ASTM C 270 and ASTM C 1714 requirements. SPEC MIX IWR Mortar is also available in standard and custom colors.

In addition to custom mix designs that are available for specific applications or properties, the standard IWR Mortar is designed to be compatible with the characteristics of the specified masonry unit. It is acceptable for all types of masonry construction with submittals available upon request. The mortar may be used above or below grade when manufactured to the appropriate specification.


• IWR Mortar is effective and comparable to mortars utilizing a liquid water repellent admixture
• Exceeded the flexural bond strength of mortar made with a liquid admixture by more than 40 percent
• Provided greater resistance to water penetration than reference mortar
• Created a water repellent masonry assemblage when used with water repellent treated units
• Demonstrated 7 and 28 day compressive strengths similar to the reference mortar. SPEC MIX® IWR Mortar is available in 80 lb. (36.3 kg.) packages for easy hand loading or in 3,000 lb. (1,360.8 kg.) reusable bulk bags to be used with the various SPEC MIX® silo systems

Reference Type N MortarType N Mortar with IWR Admixture
ASTM C 270
Water Retention89%93%
7-Day Compressive Strength1520 psi1570 psi
28-Day Compressive Strength1730 psi1800 psi
ASTM E 514
Time of First Dampness60 minNone
Time of First Visible WaterNoneNone
Area of Dampness (% of test area)10%None
Water Collected in 4 HoursNoneNone
Reference Type S Masonry MortarTYPE S Masonry Mortar with IWR Admixture
ASTM C 270
Water Retention86%86%
7-Day Compression Strength1570 psi1600 psi
28-Day Compressive Strength1950 psi2040 psi
ASTM E 514
Time of First Dampness38 minNone
Time of First Visible WaterNoneNone
Area of Dampness (% of test area)12%None
Water Collected in 4 HoursNoneNone
SPEC MIX D2W Workhorse
SPEC MIX BRICKLAYER 500 Regional Series