CMC 华盛顿特区历史悠久的西德尼·R·耶茨联邦大厦的着色黑色砌筑砂浆的实验室分析 2021

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公子舒夜 2026-06-01 21 2.3MB 32 页 15星币
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CONSTRUCTION MATERIALS CONSULTANTS, INC.
Laboratory Analyses of
A Pigmented Black Masonry Mortar
From The Historic Sidney R. Yates Federal Building
In Washington, D.C.
Sidney R. Yates Federal Building
Washington, D.C.
March 30, 2021
CMC 0321109
CONSTRUCTION MATERIALS CONSULTANTS, INC.
Sidney R. Yates Federal Building, Washington, D.C.
TABLE OF CONTENTS
Laboratory Analyses Of A Pigmented Black Masonry Mortar From The Historic Sidney R. Yates Federal Building In
Washington D.C. .............................................................................................................................................. 1!
Abstract ..................................................................................................................................................... 1!
Introduction ............................................................................................................................................... 2!
Methodologies ........................................................................................................................................... 4!
Optical Microscopy ............................................................................................................................. 5!
Scanning Electron Microscopy & Microanalysis By Energy-Dispersive X-Ray Spectroscopy (SEM-EDS) ..... 6!
Acid Digestion ..................................................................................................................................... 7!
Soluble Silica From Cold Acid & Hot Alkali Digestion ........................................................................... 8!
Weight Losses On Ignition .................................................................................................................... 8!
X-Ray Diffraction (XRD)........................................................................................................................ 8!
X-Ray Fluorescence (XRF) ..................................................................................................................... 9!
Thermal Analyses (TGA, DTG, And DSC) ............................................................................................ 10!
Fourier Transform Infra-Red Spectroscopy (FT-IR) ................................................................................ 11!
Ion Chromatography .......................................................................................................................... 11!
Results ..................................................................................................................................................... 13!
Grain-Size Distribution Of Sand In Mortar ........................................................................................... 13!
Optical Microscopy Of Sand .............................................................................................................. 14!
Optical Microscopy Of Paste .............................................................................................................. 14!
Air In Mortar ...................................................................................................................................... 14!
Paste Compositions And Microstructure Of Mortar From SEM-EDS ....................................................... 21!
Mineralogy Of Mortar From XRD ........................................................................................................ 23!
Composition Of Mortar From XRF (Major Element Oxides), Acid & Alkali Digestion (Soluble Silica), Loss
On Ignition (Free Water, Combined Water, Carbonation), And Acid-Insoluble Residue Content (Siliceous
Sand Content) .................................................................................................................................... 24!
Ion Chromatography Of Mortar........................................................................................................... 25!
FTIR Analysis Of Mortar ..................................................................................................................... 25!
Discussions .............................................................................................................................................. 26!
Type Of Mortar & Its Ingredients ......................................................................................................... 26!
Mix Calculations Of Mortar ................................................................................................................ 26!
Condition .......................................................................................................................................... 26!
Replacement Mix For Mortar .............................................................................................................. 26!
References ............................................................................................................................................... 27!
CONSTRUCTION MATERIALS CONSULTANTS, INC.
Sidney R. Yates Federal Building, Washington, D.C. 1
LABORATORY ANALYSES OF A PIGMENTED BLACK MASONRY MORTAR FROM THE HISTORIC
SIDNEY R. YATES FEDERAL BUILDING IN WASHINGTON D.C.
ABSTRACT
Founded in 1878-1880, the historic Sidney R. Yates Federal building is located in the National Mall in Washington, D.C.
As part of the renovation process, three severely fragmented, damp, pigmented black mortar samples were provided from
which one sample was selected for detailed laboratory testing to determine the type of mortar used, including composition
and grain-size distribution of sand, type(s) of the binder(s) added, and volumetric proportions of binder(s) to sand. The
sample was analyzed by comprehensive laboratory examinations, e.g., by following the methods of ASTM C 1324 and
RILEM including optical microscopy, scanning electron microscopy and X-ray microanalyses (SEM-EDS), chemical
analyses (gravimetry), X-ray diffraction (XRD), X-ray fluorescence (XRF), FTIR spectroscopy, and ion chromatography.
Based on detailed laboratory studies, the mortar is determined to be representative of a hydraulic magnesian or dolomitic
lime mortar, made using an estimated 1-part hydraulic lime to 2-part river sand, which is not equivalent to any modern-
day ASTM C 270 mortars, but very consistent with many historic pigmented lime mortars used during the late 19th century,
when quicklime was prepared by calcination of impure magnesian (or dolomitic) limestone to have a hydraulic property,
and added to the sand as a lime putty. A modern equivalent is the natural hydraulic lime (NHL) mortar.
Optical microscopy of mortar has determined its hydraulic lime and silica sand composition from: (a) characteristic
mineralogies of sand and binder, (b) carbonated microstructure and composition of paste having a carbonated lime paste
microstructure having scattered carbonated lime lumps often with characteristic carbonation shrinkage microcracks, and
occassional semi-amorphous hydraulic component in residual calcined lime; and, (c) siliceous (river) sand of dominantly
quartz-quartzite compositions, which is noticeably finer than the modern ASTM C 144 masonry sand (less than 2 mm in
nominal size), consisting of major amounts of variably strained quartz and subordinate amounts of variably strained
quartzite, chert, and feldspar particles. Chert and strained quartz, quarzite particles in sand, though potentially alkali-
silica reactive, showed no evidence of such a reaction. Sand was probably derived from the nearby Potomac river. SEM-
EDS analyses of mortar paste has confirmed the presence of a hydraulic lime binder where lime has a magnesian
composition as determined from compositional analysis of paste in SEM-EDS. SEM-EDS analysis also confirmed the
hydraulic composition of binder from the high silica content of paste compared to a non-hydraulic lime, as well as paste-
cementation index (after Eckel 1922) varying from 1.3 to 2.0 with a typcial increasing range of CI with increasing silica
and decreasing lime contents of paste, trends that are anticipated for a cement-lime or a hydraulic lime mortar. XRD
analysis has confirmed dominant quartz from quartz sand and subordinate calcite from carbonated lime paste. XRF studies
of acid and alkali-digested filtrates of mortar showed detectable soluble silica from the hydraulic binder. Detectable
magnesia component in paste from SEM-EDS is consistent with use of a magnesian or dolomitic lime binder component,
which was probably added as a lime putty where quicklime was manufactured from calcination of a magnesian limestone.
Results obtained from microscopy, and chemical analyses are all consistent, confirmatory to each other, and provided a
comprehensive understanding of mortar, which was determined to be prepared from mixing major amount of hydraulic
magnesian or dolomitc lime putty and siliceous natural (river) sand.
Based on: (i) the determined magnesian or dolomitic hydraulic lime binder composition of mortar from microscopy and
chemical analyses; (ii) essentially siliceous sand compositions of aggregate; and (iii) ‘estimated’ volumetric proportions of
1-part lime to 2-part river sand, a possible replacement mortar mix could be made using: (a) natural hydraulic lime (e.g.,
NHL 3.5), (b ) a modern ASTM C 144 masonry sand, and, (c) a carbon-based pigment at a carefully controlled dosage to
match with the existing mortar. Overall appearance of the final mortar would depend on a match on the overwhelming
pigment component that has obliterated the sand and paste. Sand to be used should match in color to the color of sand
in the present mortar, preferably from a similar source, free of any debris, unsound, clay particles, or any potentially
deleterious constituents, should conform to the size requirements of ASTM C 144 for masonry sand, and should be
durable. Due to years of atmospheric weathering and alterations, an exact match in color to the existing mortar may not
be possible, which, even if possible, could alter in future due to continued atmospheric weathering in the presence of
oxygen, moisture, and other elements.

标签： #黑色 #实验室 #分析

摘要：

本文档针对CMC在华盛顿特区历史悠久的西德尼·R·耶茨联邦大厦项目中，对用于修复工程的着色黑色砌筑砂浆进行的2021年实验室分析。研究重点在于通过化学和物理测试方法，评估该砂浆的组成成分、颜色一致性、粘结强度以及与历史建筑原有材料的兼容性，以确保修复工作既符合历史保护标准，又具备长期耐久性。分析结果揭示了色料类型、配比及施工工艺对砂浆性能的影响，为类似历史建筑维护提供了科学依据，同时强调了现代材料在尊重传统工艺中的关键作用。本报告适用于建筑保护专家、修复工程师及历史遗产管理者，旨在推动既保持建筑

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作者：公子舒夜 分类：专业资料 价格：15星币 属性：32 页 大小：2.3MB 格式：PDF 时间：2026-06-01

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