Infrared thermography has the potential to detect subsurface delaminations before spalling develops and could be used to improve the visual inspection of concrete bridges. The technology has traditionally been applied to bridge decks, which are exposed to radiant heating from the sun that helps develop the necessary thermal gradients in the concrete. Thermal gradients can also be developed from normal diurnal temperature variations. Convective heat transfer develops the thermal gradients, although these thermal gradients are of much lower magnitude than those developed through radiant heating from the sun. This paper presents the results of a study to develop thermal imaging for the detection of subsurface deterioration in the soffit areas of bridges; these soffit areas are shaded and therefore are not exposed to radiant heating from the sun. Experimental studies and field testing were conducted and are described. This paper reports on guidelines developed for this application of the technology; the guidelines address the necessary environmental conditions to enable the detection of damage in bridge soffit areas. Specifically, the paper discusses the rates of change in ambient temperature needed to ensure that subsurface damage can be detected in shaded conditions. The paper also discusses the effect of wind speed on the detectability of subsurface damage in the shaded areas of a bridge, as well as the camera settings needed to ensure that an inspector can detect temperature anomalies associated with subsurface damage. A field example is provided to illustrate the application of the technology and highlight the required camera settings.

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Coir has been known as a potential natural fiber for many sustainable construction material developments due to its wide availability and sustainable resource of coconut tree. This research study aims to investigate the flexural, compressive and tensile properties of concrete incorporating coir fiber and to find the fiber content which gives optimum results. In this study, coir concrete specimens were cast and tested with variations of fiber content of 0%, 0.25%, 0.5%, 0.75%, and 1% by weight of aggregates. Flexural test was conducted based on SNI 4431:2011, compressive test was conducted based on SNI 1974:2011 and tensile test was conducted based on SNI 2491:2014. Slump tests and unit weight showed reduced values when fiber content was increased. Flexural, compressive and tensile strengths of coir-concrete at a 28-day curing were optimum for the variation with 0.25% fiber content. Compressive strength of control concrete at 28 days was approximately 23 MPa while BS-0.25 was 27.5 MPa. Flexural strength of control concrete was 5 MPa while BS-0.25 was 6 MPa. Tensile strength of control concrete was 3 MPa while BS-0.25 was 2.5 MPa. Results from the study showed that the presence of 0.25% fiber (by total weight of aggregate) in the concrete gives approximately 19% improvement in 28 days compressive strength and flexural strength.

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