Petrographic Analysis: Concrete, Mortar, Aggregates and Rock
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当混凝土问题的发展,期间construction or later in the structure’s service life, petrographic examination is one of the most useful techniques to determine the underlying cause(s). Petrographic examination uses transmitted, reflective, and polarized light microscopy. In addition, other instrumentation and analytical techniques may also be used. These include X-Ray Diffraction (XRD), X-Ray Fluorescence (XRF), Fourier-Transformed Infrared (FTIR) and various other chemical methods. Depending on the complexity of the project, a high-powered microscope, such as the Scanning Electron Microscope (SEM) may also be used. These tools help determine the cause(s) of concrete distress and provide an understanding of material properties and how they can impact performance.
AT BRAUN INTERTEC, WE CAN EVALUATE A NUMBER OF MATERIALS TO IDENTIFY ISSUES OR FOR QUALITY CONTROL
Concrete
Concrete distress can be related to physical or chemical attacks on concrete. Determining the root cause of an issue observed in the field is the primary reason for conducting petrographic examination on concrete samples. We use petrography to investigate several concrete issues, including:We use petrography to investigate several concrete issues, including:
- Causes of surface defects such as: Scaling, Popouts, Cracking, Delamination, and Dusting
- Identifying reactive aggregates and various aggregate issues such as:
Alkali-Silica Reaction (ASR), Alkali-Carbonate Reaction (ACR), sulfate attack from pyrrhotite, high clay content from fine aggregate
- Determining air-void content and parameters of the air-void system
- Estimating water-to-cement(itious) ratio
- Investigating for the presence of mineral admixtures or pozzolans, and estimating relative percentage of cementitious materials
- Cause(s) of low strengths
- Extent of fire damage
- Freeze-Thaw or Frost damage
- Chemical attack
- Identifying efflorescence and secondary deposits
- Identifying penetrating sealers and overlay systems
Mortar
Our laboratory is well-versed in investigating historic structures, as well as new construction, where mortar issues are of concern.
岩相检验砂浆可以帮助:
- Identify cementitious materials and aggregates
- Calculate mortar proportions
- Estimate mortar types M, S, N or O
- Design tuck pointing mortar
- Perform failure analyses of masonry walls
Aggregates and Rocks
The petrographic examination of aggregates provides valuable data on the durability and/or potential deleterious effects of the aggregate when used in concrete. The evaluation is often performed in conjunction with physical testing. Our petrographic laboratory can perform examinations on both manufactured and natural materials to meet your project needs. Petrographic examination may be performed for the various purposes:
Petrographic examination may be performed for the various purposes:
- Exploration for new or existing viable sources
- Quality control of source
- Identifying potentially deleterious aggregates
- Durability information for riprap and erosion control stone
- Micro and macroscopic description of rock for geotechnical, environmental, or mining purposes
Qualifications and Experience
Braun Intertec is an AMRL* accredited and U.S. Army Corps of Engineers validated laboratory providing a detailed analysis of concrete, mortar, aggregates, rock, and other cementitious building materials. Our staff has more than 50 years combined experience investigating concrete and aggregates issues.
Our petrographic services are centered around four ASTM procedures:
- ASTM C 856 “Standard Practice for Petrographic Examination of Hardened Concrete”
- ASTM C 457 “Standard Test Method for Microscopical Determination of Parameters of the Air-Void System in Hardened Concrete”
- ASTM C 1324 “Standard Test Method for Examination of Hardened Masonry Mortar”
- ASTM C 295 “Standard Guide for Petrographic Examination of Aggregates for Concrete”
Please contact us for evaluation using other standards and test methods by filling out the contact us form on the right.
* American Association of State Highway and Transportation Officials (AASHTO) Materials Reference Laboratory