Structural Engineering Services Across Southern California
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Forensic Damage Evaluation Reports
Damage Evaluation Reports
We currently provide forensic engineering evaluation services for buildings that have experience damage related to water intrusion, seismic, or foundation settlement.
Many buildings experience concrete degradation and steel reinforcement (rebar) corrosion due to water permeating through the concrete.
In general, the following is true for any exposed and unprotected concrete slab:
- Concrete absorbs water through its air pores and water permeates through concrete like water slowly passing through a sponge by way of gravity.
- As water moves through concrete, it carries with it chloride ions from oceanic wind-blown airborne salt spray which corrodes internal steel rebar. Acid rain carries sulfuric and nitric acids from atmosphere and attack calcium compounds of concrete causing deterioration of cementitious compounds. A similar phenomena occurs during carbonation caused by carbon dioxide mixed with atmospheric moisture: alkalinity of concrete is reduced and internal bonds are degraded.
- Cyclical patterns of saturation and drying causes chlorine and weak acid build-up in the concrete, thereby reducing the pH while increasing the acidity. Any pH less than 10, will allow internal steel rebar to corrode.
- When the steel rebar corrodes, it expanded in volume. As expansion occurs in steel rebar, it pushes against the surrounding concrete causing the concrete to de-bond with the rebar, crack, bulge at the surface of the concrete, and spawl (detachment) away from the rebar. Because concrete is weak in tension, bulging and spawling eventually occur due to the amount of corrosion in the steel rebar.
- Water will continue to penetrate through the concrete past the initial degraded regions. Eventually, the process of internal concrete chemical deterioration will occur at new areas and rebar in these newly affected areas will also corrode.
All of this can be referred to as degradation.
We use non-destructive testing (NDT) and destructive testing as indicated below.
Our reports are based on industry standards such as:
- ACI Committee 228, Nondestructive Test Methods for Evaluation of Concrete in Structures, ACI 228.2R, American Concrete Institute, Farmington Hills, Michigan.
- ICRI Technical Committee 210, 210.4R-2021 – Guide for Nondestructive Evaluation Methods for Condition Assessment, Repair, and Performance Monitoring of Concrete Structures, International Concrete Repair Institute, St. Paul, MN.
- The International Concrete Repair Institute (ICRI) and the American Concrete Institute (ACI) Committee 562 have recently published standards for engineers to develop assessments of damaged concrete structures such as the “ACI 562-19 Code Requirements for Assessment, Repair, and Rehabilitation of Existing Concrete Structures.” Our evaluation is based on the relevant sections of the ACI 562-19.
- Accordingly, the relevant definitions for “substantial structural damage” and the relevant section 405.2 of the 2019 California Existing Building Code (CEBC) and the 2018 International Existing Building Code (IEBC) are incorporated where these codes have been adopted by the local authority having jurisdiction (AHJ).
Once the test results from the non-destructive testing and destructive testing are received by our firm, we will modify the repair section of this report to ensure the repair approach prescribes incorporates the information received from these test results.
The following additional information is required to provide a thorough and accurate repair prescription. From the following information we can better understand the concrete engineering properties and quality, characteristics, and damage of the concrete and rebar.
Required Non-Destructive Testing & Evaluation
- Quality of concrete: extent/width/depths/ocations of delamination, internal flaws, voids, internal crack, and honeycomb
- Impact echo (IE), pulse echo, ultrasonic pulse velocity (UPV) tests, MIRA ultrasonic tomography; (ASTM C1740 and ASTM C1383).
- These test methods permit high-speed scanning, are very sensitive to presence of embedded metal objects., have the ability to penetrate across concrete-air interfaces, and are sensitive to the presence of moisture and chlorides.
- Spectral Analysis of Surface Waves (SASW)
- Infrared thermography (IRT, ASTM D4788)
- Durability performance: Corrosion activity/rate/potential/resistance of concrete & embedded steel rebar
- Electrochemical methods: GeCor, and GalvaPulse galvanostatic pulse measurements
- Half-cell potential (ASTM C876) and
- Infrared thermography (IRT, ASTM D4788)
- Durability performance: Corrosion activity/rate/potential/resistance of concrete & embedded steel rebar
- Electrochemical methods: GeCor, and GalvaPulse galvanostatic pulse measurements
- Half-cell potential (ASTM C876) and
- Linear polarization (SHRP-S-324 and SHRP-S-330)
- Location of structural reinforcement
- X-ray radiography
- g-ray radiography
- Covermeter
- Concrete compressive strength
- Schmidt (Rebound) Hammer tests
Required Destructive Testing & Evaluation
- Compression strength tests and Reinforcement yield strength tests by core sample testing at the locations identified in Appendix 3.
- In accordance with ACI 562-19 section 6.4., perform concrete core samples for compression strength tests and reinforcement yield strength tests at the locations identified in Appendix 3. The core must be through rebar. Scanning of the slab for rebar locations is required prior to the core being taken. These locations were selected to ensure any internal concrete spawling at expanded top and/or bottom layers of rebar is examined.
- In accordance with ACI 562-19 section 6.4.5.1, take 3 cuopons from different areas to determine yield strength of steel rebar (ASTM A370)
- The test results shall be given to the civil or structural engineer hired to perform the final design of the repairs.
- Equivalent specified compressive strength of the concrete shall be calculated from equation 6.4.3.1 in ACI 562-19.
- Equivalent specified yield strength of the rebar shall be calculated from equation 6.4.6 in ACI 562-19.
- Quality of concrete and degree of damage
- Petrography testing (Petrographic Analysis; Chemical and microscopic analysis) on the cores at the lab. Sections of cores should be treated with uranyl acetate (UA) and exposed to ultraviolet light and Alkali-silica gel to reveal characteristics.
- Carbonation testing (pH testing) on freshly fractured surface of concrete using phenolphthalein (qualitative indication); pH meter Fiber optic pH sensors embedded in concrete
- Chloride ion content test by acid-soluble (ASTM C1152) and water-soluble (ASTM C1218) tests
[1] ACI Committee 228, Nondestructive Test Methods for Evaluation of Concrete in Structures, ACI 228.2R, American Concrete Institute, Farmington Hills, Michigan. (ACI 228.2R-13)
ICRI Technical Committee 210, 210.4R-2021 – Guide for Nondestructive Evaluation Methods for Condition Assessment, Repair, and Performance Monitoring of Concrete Structures, International Concrete Repair Institute, St. Paul, MN.