Evaluation of Treatment Options for ASR-Affected Concrete: FHWA-WY-10/01F
This research project was undertaken to evaluate the potential of using surface treatments including lithium nitrate, sodium tartarate, siloxanes, silane, and boiled linseed oil to mitigate or slow the rate of concrete deterioration associated with alkali-silica reaction (ASR). Significant amounts of concrete pavements, curbs and gutters, sidewalks, etc. across Wyoming suffer from ASR and related freeze/thaw damage. Any extension of the service life of concrete through remediation can result in significant cost savings to Wyoming Department of Transportation (WYDOT). Also, materials and pavement engineers need methods to evaluate damage and rates of deterioration to help assess the life cycle of ASR-affected concrete.
Specific objectives of this investigation were: 1) evaluate the effectiveness of applying various surface treatments to mitigate or slow down the deterioration rate associated with ASR, 2) evaluate the appropriateness of using the Damage Rating Index (DRI) and ultrasonic pulse velocity (UPV) methods for assessing concrete damage and determining the rate of deterioration caused by ASR.
Scope of work included: a condition survey of the ASR deteriorated concrete air service apron at the Riverton
Regional Airport; extracting “before” treatment cores for petrographic examination, and determining DRI scores and measuring wave velocities using UPV; apply surface treatments to seven of nine test panels; wait five years and perform a second or “after” treatment survey, and extract “after” treatment cores located adjacent to the “before” cores; perform a second round of petrographic examinations and measure DRI scores and wave velocities. Next, compare the “before” and “after” test results, evaluate the effectiveness of the surface treatments, and determine if the DRI and UPV methods are appropriate for assessing concrete damage and establishing rates of deterioration.
Although the study was prematurely terminated after two years, valuable information was obtained: 1) DRI and
UPV methods did measure ASR related damage and deterioration; however, correlation of the measured damage and rates of deterioration between these methods was poor. 2) Test results indicated that surface treatments consisting of lithium nitrate, sodium tartarate and siloxane may reduce the rate of ASR deterioration. However, no firm conclusions were made because of the limited samples tested and conflicting test results from DRI and UPV.
This report presents: discussions about ASR, DRI, UPV, test results, comparisons of DRI and UPV test results for “before” and “after” concrete samples representing test panels treated with lithium nitrate, sodium tartarate,
siloxanes, silane, and boiled linseed oil. Conclusions and recommendations are also presented.