SBIR-STTR Award

Laser Technology Inc. has demonstrated for the first time, the detection of non-visible cracks of less than 10 microns soon after casting of high performance concrete test prisms. Fine cracks may be associated with the two leading causes of concrete deterioration, delayed ettringite formation and alkali-silica reaction. Laser Technology is a leading developer, manufacturere and provider of laser shearography systems for aerospace and tire nondestructive testing. We have developed multiple portable systems for military aircraft and production systems for most major aerospace programs world wide. The use of the shearography crack detection system for DEF and ASR research will lead to a better understanding of these processes, improved high performance concrete processes and inspection capability to predict structural degradation on the nations infrastructure.

Laser Technology Inc. (LTI) proposes a Phase II SBIR research project to further develop a Compact Shearography System, Analysis Method and Software for micro-crack detection in concrete. There is an urgent need to detect and characterize fine cracks in concrete that form because of various damage mechanisms including alkali-silicate reaction, delayed ettringite formation or frost damage. Fine shrinkage cracks do not pose a structural problem in the static sense, their presence can promote deterioration processes that over time can lead to failure. They allow water to penetrate, which can lead to ASR and DEF, the corrosion of steel reinforcements and fatigue cracks. Work performed by the researchers herein demonstrated shearography can detect non-visible cracks in concrete. Under a Phase I SBIR, we developed and field demonstrated a prototype instrument for micro-crack detection in concrete. Under the Phase II proposed work plan, LTI will further develop the equipment hardware and software for crack analysis and test a number of concrete samples. Shearography will be used to evaluate the HIPERPAV II concrete shrinkage crack model using a modified VTT Finnish early age shrinkage test. We will conduct literature search of crack detection and measurement methods and compare performance with the developed shearography system.