Nicholas J. Carino

Bio: Nicholas J. Carino is an academic researcher from National Institute of Standards and Technology. The author has contributed to research in topics: Compressive strength & Wave propagation. The author has an hindex of 28, co-authored 68 publications receiving 3199 citations.

CRC Handbook on Nondestructive Testing of Concrete

Abstract: Surface Hardness Methods. Penetration Resistance Methods. Pullout Test. Breakoff Test Method. The Maturity Method. Resonant Frequency Methods. Pulse Velocity Methods. Combined Methods. Magnetic/Electrical Methods. Radioactive/Nuclear Methods. Short Pulse Radar Methods. Stress Wave Propagation Methods. Infrared Thermographic Techniques. Acoustic Emission Methods.

Effects of Test Conditions and Mixture Proportions on Behavior of High-Strength Concrete Exposed to High Temperatures

Abstract: In this research, mechanical properties of high-strength concrete exposed to elevated temperatures were measured by heating 100 x 200 mm cylinders at 5 deg C/min to temperatures of up to 600 deg C. Heating was conducted with/without sustained stress, and properties were measured at elevated temperatures and after cooled to room temperature (RT). 4 mixes with water-cementitious materials (w/cm) ratios ranging from 0.22-0.57 and RT strengths ranging from 51-98 MPa were used. 2 of the mixtures contained silica fume. Measured compressive strengths and elastic moduli were normalized with respect to RT values, and analysis of variance was used to determine whether the test condition, the value of w/cm, or the presence of silica fume affected results. The influence of these variables on the tendency for explosive spalling was also examined. Results show that losses in relative strength due to high-temperature exposure were affected by the test condition and w/cm, but there were significant interactions among the main factors that resulted in complex behaviors. The presence of silica fume does not appear to have a significant effect. Measurements of temperature histories in the cylinders revealed complex behaviors believed to be linked to heat-induced transformations and transport of free/chemically combined water.

The Maturity Method: Theory and Application

Abstract: The maturity method may be used to predict the in-place strength of hardening concrete based on its thermal history A theoretical basis for the maturity method is presented The general form of the time-temperature function is found to be the time integral of the rate constant For the case of linear dependence between temperature and the rate constant, the time-temperature function becomes the traditional maturity function The Arrhenius equation is shown to be an accurate representation of the temperature dependence of the rate constant, and the concept of equivalent age is explained for practical application of the Arrhenius equation It is explained how the accuracy of strength prediction by the traditional maturity method can be improved by using the proper datum temperature Results illustrate that the appropriate value of apparent activation energy or datum temperature for concrete may be obtained from strength-gain data of isothermally cured mortar specimens

The Impact-Echo Method: An Overview

Abstract: The impact-echo method is a technique for flaw detection in concrete. It is based on monitoring the surface motion resulting from a short-duration mechanical impact. The method overcomes many of the barriers associated with flaw detection in concrete based on ultrasonic methods. The purpose of this paper is to provide an overview of the technique and to discuss the important parameters involved in this type of testing. One of the key features of the method is the transformation of the recorded time domain waveform of the surface motion into the frequency domain. The impact gives rise to modes of vibration and the frequency of these modes is related to the geometry of the test object and the presence of flaws. The principles involved in frequency analysis are discussed. The importance of the impact duration in relation to flaw detection and other factors affecting the smallest flaw that can be detected are also reviewed. The paper concludes with a summary of the ASTM standard governing the use of the impact-echo method for measuring the thickness of plate-like structures.

Review Paper: Health Monitoring of Civil Infrastructure:

Abstract: Increased awareness of the economic and social effects of aging, deterioration and extreme events on civil infrastructure has been accompanied by recognition of the need for advanced structural health monitoring and damage detection tools. Today, these tasks are done by visual inspection and very traditional methods such as the tap test. This labor-intensive task is done at a frequency of less than once every two years for bridges, and on an as-needed basis for other infrastructures such as buildings. Structural health monitoring techniques based on changes in dynamic characteristics have been studied for the last three decades. When the damage is substantial, these methods have some success in determining if damage has occurred. At incipient stages of damage, however, the existing methods are not as successful. A number of new research projects have been funded to improve the damage detection methods including the use of innovative signal processing, new sensors, and control theory. This survey paper hig...

Review of NDT methods in the assessment of concrete and masonry structures

Abstract: This paper reviews the state of non-destructive testing (NDT) methods as applied to the civil engineering industry in the Millennium Year, 2000. The basic principles of NDT methods are described with particular reference to the five major factors that influence the success of a survey: depth of penetration, vertical and lateral resolution, contrast in physical properties, signal to noise ratio and existing information about the structure. The main NDT methods used in engineering investigations are discussed and illustrated with brief case histories from the literature. The integration of NDT surveys into the investigation of structures is described. The underlying reasons why NDT methods are perceived as ‘not working’ by the structural engineer are identified as: a lack of understanding of variability of both the construction materials used and NDT methods themselves.

Wind Turbine Condition Monitoring: State-of-the-Art Review, New Trends, and Future Challenges

Abstract: As the demand for wind energy continues to grow at exponential rates, reducing operation and maintenance (OM) costs and improving reliability have become top priorities in wind turbine (WT) maintenance strategies. In addition to the development of more highly evolved WT designs intended to improve availability, the application of reliable and cost-effective condition-monitoring (CM) techniques offers an efficient approach to achieve this goal. This paper provides a general review and classification of wind turbine condition monitoring (WTCM) methods and techniques with a focus on trends and future challenges. After highlighting the relevant CM, diagnosis, and maintenance analysis, this work outlines the relationship between these concepts and related theories, and examines new trends and future challenges in the WTCM industry. Interesting insights from this research are used to point out strengths and weaknesses in today’s WTCM industry and define research priorities needed for the industry to meet the challenges in wind industry technological evolution and market growth.