original existing historic materials as closely as possible in composition,
color, texture, strength, size, finishing and porosity.
2.3.2
Cementitious Materials
Cementitious materials shall be of one type and from one source, when used
in mortar which will have surfaces exposed in the finished structure.
Cement composition shall match that of cement used in existing mortar to be
repaired, as determined by samples and testing, and shall conform to the
basic requirements of ASTM C 150, Type [I] [II] [low alkali].
2.3.3
Epoxy Anchor Adhesives
An epoxy-resin
grout shall be used to bond steel anchors to masonry, and
shall be a 100
percent solids, moisture insensitive, low creep, structural
adhesive. The
epoxy shall conform to ASTM C 881/C 881M, Type IV; Grade and
Class selected
to conform to the manufacturer's recommendations for the
application.
2.3.4
Metal attachments
Anchors for spall repairs shall be threaded stainless steel, size as
indicated. Other plates, angles, anchors, and embedments shall conform to
ASTM A 36/A 36M, and shall be prime painted with inorganic zinc primer.
PART 3
EXECUTION
3.1
EVALUATION AND ANALYSIS
Evaluation and analysis shall conform to the requirements specified herein,
and to Section 01451A CONTRACTOR QUALITY CONTROL. Masonry renovation shall
be undertaken only after complete evaluation and analysis of the areas to
be repaired are completed; this shall include sampling and testing of the
existing mortar to determine its composition and qualities. No repair work
shall be undertaken until conditions that have caused masonry deterioration
have been identified; such conditions shall be corrected, if possible,
prior to start of the work.
3.2
MASONRY CLEANING
Historic materials shall not be damaged or marred in the process of
cleaning. Cleaning shall conform to [ASTM C 1515] [BIA Tech Note 20].
Open joints shall be temporarily caulked or otherwise protected to prevent
water and cleaner intrusion into the interior of the structure from
pressure spraying. Non-masonry materials and severely deteriorated masonry
shall be protected by approved methods prior to initiation of cleaning
operations. Masonry cleaning shall remove all organic and inorganic
contaminants from the surface and pores of the substrate, returning the
masonry to its natural color. Surfaces shall be evenly cleaned with no
evidence of streaking or bleaching. The cleaning process shall not affect
the density, porosity, or color of the masonry or mortar. Cleaned masonry
shall have a neutral pH. Methods used for cleaning historic masonry shall
be the gentlest possible to achieve the desired results. Test patches
shall be made to determine a satisfactory cleaning result. Cleaning shall
proceed in an orderly manner, working from top to bottom of each scaffold
width and from one end of each elevation to the other. Cleaning shall be
performed in a manner which results in uniform coverage of all surfaces,
including corners, moldings, interstices and which produces an even effect
without streaking or damage to masonry. The cleaning materials, equipment,
SECTION 04900
Page 13
Previous Page
