Pozzolanic Hydraulic Lime
A type of lime that has been used in construction since ancient Roman times is now covered by an ASTM International standard. ASTM International Committee C07 on Lime has approved C1707, Specification for Pozzolanic Hydraulic Lime for Structural Purposes. The new standard is under the jurisdiction of Subcommittee C07.02 on Specifications and Guidelines.
According to Margaret Thomson, technical manager for Chemical Lime Co. and C07 vice chair, the new specification defines the plastic and hardened properties of a blended material consisting of single or multiple pozzolans and Type S hydrated lime (covered in C207, Specification for Hydrated Lime for Masonry Purposes).
The material detailed in C1707 takes advantage of the cementitious or hydraulic properties of the pozzolanic reaction with Type S hydrated building lime in the presence of moisture and the plastic and hardened properties as well as the carbonation properties of lime. Lime covered in the standard will be used in the production of mortars and interior-exterior plasters.
“This is a new ‘old’ material,” notes Thomson. “The Romans used pozzolans in the form of volcanic ash and ground brick dust with lime as mortar and plaster. Developing a standard specification for a pozzolanic hydraulic lime provides the needed framework for cementitious materials manufacturers and users looking to innovate their mortars and plasters toward reducing the carbon dioxide emission and embodied energy impact of cementitious building materials.”
Technical Information: Margaret Thomson, Chemical Lime Co., Henderson, Nev.
ASTM Staff: Kevin Shanahan