Assessment of moisture and porosity effects in failure mechanism of mortar using Acoustic Emission

Author
M. ahmadi
tarbiat modares
Abstract
Different methods are being used for monitoring of crack growth and failure mechanism in rock fracture. Acoustic Emission (AE) is one the methods used for micro crack monitoring in samples under pressure. Existence of porosity and humidity in rock and soil structure cause different effects on process of micro cracks and growth of micro cracks and finally their fracture. In this study, effects of porosity and humidity in micro crack growth and rock fracture are being analyzed. Four parameters which are highly effective in AE method namely hit, count, wave durability and fracture energy are used. Mortar (synthetic rock) was used to have a constant porosity ratio in samples. Cylindrical samples with 54 mm diameter and 110 mm length with 5 different porosity ratios ranging from 17 to 35 percent were made using Panplast lubricant. Samples were subjected to uniaxial compression test in two dry and saturated conditions and AE data were recorded. Data analysis showed that the dominant failure mode on samples of dry mortar with increasing porosity, increase toward the tension mode. With increasing of porosity and moisture content the numbers of micro crack decreases. Different methods are being used for monitoring of crack growth and failure mechanism in rock fracture. Acoustic Emission (AE) is one the methods used for micro crack monitoring in samples under pressure. Existence of porosity and humidity in rock and soil structure cause different effects on process of micro cracks and growth of micro cracks and finally their fracture. In this study, effects of porosity and humidity in micro crack growth and rock fracture are being analyzed. Four parameters which are highly effective in AE method namely hit, count, wave durability and fracture energy are used. Mortar (synthetic rock) was used to have a constant porosity ratio in samples. Cylindrical samples with 54 mm diameter and 110 mm length with 5 different porosity ratios ranging from 17 to 35 percent were made using Panplast lubricant. Samples were subjected to uniaxial compression test in two dry and saturated conditions and AE data were recorded. Data analysis showed that the dominant failure mode on samples of dry mortar with increasing porosity, increase toward the tension mode. With increasing of porosity and moisture content the numbers of micro crack decreases. Different methods are being used for monitoring of crack growth and failure mechanism in rock fracture. Acoustic Emission (AE) is one the methods used for micro crack monitoring in samples under pressure. Existence of porosity and humidity in rock and soil structure cause different effects on process of micro cracks and growth of micro cracks and finally their fracture. In this study, effects of porosity and humidity in micro crack growth and rock fracture are being analyzed. Four parameters which are highly effective in AE method namely hit, count, wave durability and fracture energy are used. Mortar (synthetic rock) was used to have a constant porosity ratio in samples. Cylindrical samples with 54 mm diameter and 110 mm length with 5 different porosity ratios ranging from 17 to 35 percent were made using Panplast lubricant. Samples were subjected to uniaxial compression test in two dry and saturated conditions and AE data were recorded. Data analysis showed that the dominant failure mode on samples of dry mortar with increasing porosity, increase toward the tension mode. With increasing of porosity and moisture content the numbers of micro crack decreases

Keywords

Subjects

1-E. E. Gdoutos, "Fracture Mechanics," Civil Engineering, p. 376, 2005.##
2-M. D. Thouless, "Fracture mechanics for thin-film adhesion," IBM Journal of Research and Development, vol. 38, pp. 367-377, 1994.##
3-J. G. DONOVAN, "Fracture toughness baced modeles for the prediction of power consumption, product size, and caplacity of jaw crushers". Virginia Polytechnic Institute and State University, 2003.##
4-M. Hassanzadeh, "Behaviour of fracture process zones in concrete influenced by simultaneously applied normal and shear displacements," Lund University, 1992.##
5-Standard, A. S. T. M. "E1316,[Standard Terminology for Nondestructive Examinations]." ASTM International, West Conshohocken, PA, DOI 10 (2007): E1316##
6-D. Lockner, "The role of acoustic emission in the study of rock fracture," in International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, 1993, pp. 883-899.##
7-S. Hu, J. Lu, and F. Xiao, "Evaluation of concrete fracture procedure based on acoustic emission parameters," Construction and Building Materials, vol. 47, pp. 1249-1256, 2013.##
8-A. Nair and C. Cai, "Acoustic emission monitoring of bridges: Review and case studies," Engineering structures, vol. 32, pp. 1704-1714, 2010.##
9-D. G. Aggelis, "Classification of cracking mode in concrete by acoustic emission parameters," Mechanics Research Communications, vol. 38, pp. 153-157, 2011.##
10-Y. Cheng, R. Mitra, and P. Hagn, "Development and future aspect of acoustic emission data processing methods," in The 30th European Conference on Acoustic Emission Testing & 7th International Conference on Acoustic Emission University of Granada, 2012, pp. 12-15.##
11-S. J. Vahaviolos, "Acoustic Emission : Standards and Technology Update," 1999.##
12-M. Aldahdooh and N. M. Bunnori, "Crack classification in reinforced concrete beams with varying thicknesses by mean of acoustic emission signal features," Construction and Building Materials, vol. 45, pp. 282-288, 2013.##
13-A. Behnia, H. K. Chai, and T. Shiotani, "Advanced structural health monitoring of concrete structures with the aid of acoustic emission," Construction and Building Materials, vol. 65, pp. 282-302, 2014.##
14-K. Ohno and M. Ohtsu, "Crack classification in concrete based on acoustic emission," Construction and Building Materials, vol. 24, pp. 2339-2346, 2010.##
15-M. Ohtsu, Y. Tomoda, and T. Suzuki, "Damage evaluation and corrosion detection in concrete by acoustic emission," Carpinteri A. et al, pp. 981-989, 2007.##
16-R. Documents, "Compressive Strength of Cylindrical Concrete Specimens," pp. 1-14, 2007.##
17-M. V. M. S. Rao, K. J. P. Lakshmi, G. M. N. Rao, K. V. Kumar, and S. Udaykumar, "on Non-Destructive Evaluation Pre-Failure Damage Caused by Micro-Cracks in Rock : A Laboratory Study Using Acoustic Emission," pp. 323-327, 2009
Modares Civil Engineering journal
Volume 18, Issue 1
May and June 2018
Pages 91-100