Forensic Evaluation

Thanks to our expertise and experience we eliminate all guesswork in the event failure occurs. We use innovative forensic techniques to accurately determine the cause of the problem.

We deliver results based on investigation, testing and analysis. We compile and report all our findings in detailed and comprehensive manner.

Petrographic Analysis - ASTM C295 & C856

ASTM C295 / C295M: Standard Guide for Petrographic Examination of Aggregates for Concrete.

ASTM C856: Standard Practice for Petrographic Examination of Hardened Concrete.

Uses of Petrographic Analysis

Petrographic analysis is the starting point in the evaluation of concrete. They include:

  1. Finding the causes of inferior quality, distress, or deterioration of concrete.
  2. Determination whether the concrete in a construction was or was not as specified.
  3. Provide description of the cementitious matrix, including qualitative determination of the kind of  hydraulic binder used, degree of hydration, degree of carbonation if present, presence of a mineral admixture, the nature of the hydration products, adequacy of curing, and unusually high water – cement ratio of the paste.
  4. Identify whether the concrete has been subjected to and affected by sulfate attack, or other chemical attack, or early freezing, or to other harmful effects of freezing and thawing.
  5. Determination whether concrete subjected to fire is essentially undamaged or moderately or seriously damaged.
  6. Determination of the factors that caused a given concrete to serve satisfactorily in the environment in which it is taken from
Forensic Evaluation (petrography) Forensic Evaluation (petrography)

Fire-damaged concrete.

Forensic Evaluation (petrography) Forensic Evaluation (petrography)

Sulfate attacked concrete

Forensic Evaluation (petrography) Forensic Evaluation (petrography)

Evaluation of granite sample

Scanning Electron Microscopy (SEM) - ASTM C1723

ASTM C1723: Standard Guide for Examination of Hardened Concrete Using Scanning Electron Microscopy.

A scanning electron microscope (SEM) by ASTM C1723, is an analytical microscope that produces images of a sample by scanning it with a focused beam of electrons. SEM is used to complement other analytical results, such as petrographic analysis. An energy dispersive X-ray, (EDX) unit attached to the SEM is also used to obtain a secondary, semi-quantitative elemental data from an area of interest on the larger photomicrograph of the SEM. It is capable of taking images with magnification on the range of 40X to 5,000X and beyond.

Differentiating between two types of grouts: Non-shrink epoxy grout and Non-shrink cementitious grout

Non-descript surface at 150X of non-shrink epoxy grout.

Shows Non Shrink cementitious grout magnified at 1500X showing crystalline hydrated cementitious materials

Shows Non Shrink cementitious grout at magnification of 5,000X

Thermogravimetric Analysis (TGA)

Thermogravimetric Analysis (TGA) measures weight changes in a material as a function of temperature (or time) under a controlled atmosphere. Its principal uses include measurement of a material’s thermal stability and composition.

Thermogravimetric Analysis instruments are routinely used in all phases of research, quality control and production operations.

Analysis Conditions:

SEIKO SSC/5200 TG/DTA 220 Thermal Analysis Station

TGA operating parameters: ceramic pans, ~ 50mg

Working gas: Argon

Temperature program: 300 to 10000C at 100C/min.

Sample Project

Thermogravimetric analysis was performed on the two grout samples from Drums 2 & 4. An overlay of the TGA profiles for both samples is provided as shown below . Drum 2 shows a total mass loss of < 1% by weight. The TGA profile of Drum 4 shows a significant mass loss of 28% occurring between ~1380C to ~9200 C

Differentiating between Non-shrink (N-S) Epoxy grout (Drum 2) and N-S Cementitious grout (Drum 4)

X-Ray Diffraction (XRD)

X-Ray Diffraction (XRD) analysis is a unique method in determination of crystalline materials such calcium hydroxide ettringite and others. XRD is primarily used for identifying crystalline material in investigative work in cement pastes and limestones in concrete. It is also widely used in several branches of sciences for similar applications.

A typical diffraction pattern for three types of hydrated cement paste give the results below:

Experience Matters

  • We provide services with advanced state of the methods to identify pertinent issues in any given situation.
  • Our reporting is succinctly presented and easy to follow.