Studies on the spatial variability of rebound hammer test results recorded at in-situ testing

Abstract

Variability of the in-situ rebound hammer tests is composed of the inherent variability of the measuring method and the spatial variability of the concrete performance properties. In-situ, Schmidt rebound hammer tests were performed at the bottom surface of a concrete slab, with dimensions of 25.0 m × 7.5 m. The studied region on was 22.0 m × 6.0 m. The analysis of the inherent variability of the rebound hammer tests was limited to the comparison of the statistical location parameters; mean, median and mode values. The spatial variability was analysed by contour plots and semivariograms of the statistical location parameters. It was demonstrated that the geostatistical methods may be applicable for the much smaller scale concrete structures than the scale of geological formations. Semivariograms and semivariogram models seem to be useful tools for the characterisation of spatial variability of concrete structures.

Variability case study based on in-situ rebound hardness testing of concrete. Part 1. Statistical analysis of inherent variability parameters

“…The mean, the median and the mode values were calculated for the 42 independent test areas and were published earlier [14]. Rather close correlation of the mean, median and mode values can be supposed for the present observations.…”

“…It can be realized that the three statistical location parameters are interrelated and a rather strong correlation is found between the mean and median values for the concrete floor in the present study [14]. Frequency histograms for the mean and median values are rather similar and can be modelled by the same type of probability distribution.…”

“…Frequency histograms for the mean and median values are rather similar and can be modelled by the same type of probability distribution. The mode values, however, indicate weaker correlation with the other two statistical location parameters and the peakedness of the corresponding frequency histogram is more pronounced [14].…”

“…The bottom surface of the top concrete slab of a framed, monolithic, subsoil concrete tunnel was studied, with dimensions of 25.0 m × 7.5 m and a thickness of 0.48 m [14]. The measuring region on the bottom surface was 22.0 m × 6.0 m. A total number of 42 test areas were selected for Schmidt rebound hammer testing.…”

Variability case study based on in-situ rebound hardness testing of concrete. Part 2. Statistical analysis of spatial variability parameters

“…Geostatistical methods are widely used in mining, geology, soil science, environmental science, hydrology, meteorology and recently, in engineering sciences for remote sensing, surface texture modelling, reliability and risk analysis, service life design and analysis of non-destructive testing [1][2][3][4][5][6][7][8][9][10]. The spatial variability analysis is well-described in the geostatistical literature for a long time; the reader may refer to the several textbooks available in geostatistics [11][12][13][14][15][16].…”