Early-age cracking is often attributed as a major cause of reduction in the durability of concrete structures. The objective of this paper is to study the hydration behavior of various samples of different water-cement ratios, that’s in order to assess crack potential, compressive strength and setting time of the cement paste. The behavior of hydration was monitored by using a non-contact electrical resistivity apparatus. While a new eccentrically steel cracking frame (ESCF), setting time and compressive strength standard test were considered to measure the restrained shrinkage cracks, compressive strength and setting time respectively. The objective of using the eccentrically sample is to provide a new method to assess the cracks at early age by presents a complicated and non-uniform circumferential stress in the eccentrically cement paste ring. The results show that the electrical resistivity measurement of all samples with different water cement ratios had similar trends. Whereas the lowest water-cement ratio paste indicates highest resistivity values, reaches an earlier inflection point, and obtained higher compressive strength than other cement pastes of higher water-cement ratio. The eccentrically restrained cracking test (ERCT) and setting time demonstrated that lower water-cement ratio paste set and cracked earliest, which is therefore, confirmed its highest cracking tendency. The cracks took place at the narrow regions of specimens, which can be an indicator for eccentrically restrained shrinkage test (ERST). The cracks were observed as growing at narrow areas and reach full-depth over time. A mathematical model for predicting the cracking age of cement is proposed. The equation showed the existence of a positive relationship between electrical resistivity represented by inflection points (Ti) and cracks time (Tc).
| [1] | J. Branston, S. Das, S. Y. Kenno, and C. Taylor, “Influence of basalt fibres on free and restrained plastic shrinkage,” Cement and Concrete Composites, vol. 74, pp. 182-190, 2016.View Article |
| [2] | H. Beushausen and N. Bester, “The influence of curing on restrained shrinkage cracking of bonded concrete overlays,” Cement and Concrete Research, vol. 87, pp. 87-96, 2016.View Article |
| [3] | ACI224, “Causes, Evaluation, and Repair of Cracks in Concrete Structures,” Technical Documents, American Concrete Institute United States, 2007.View Article |
| [4] | H. M. Aktan, G. Fu, W. Dekelbab, and U. Attanayaka, “Investigate causes & develop methods to minimize early-age deck cracking on Michigan bridge decks,” 2003.View Article |
| [5] | M. A. Saadeghvaziri and R. Hadidi, “Cause and control of transverse cracking in concrete bridge decks,” 2002.View Article |
| [6] | S. M. Bawa, X. Wei, and L. Wang, “The relationship between electrical resistivity of cement paste and its restrained shrinkage crack with the aid of novel apparatus and ANSYS simulation,” KSCE Journal of Civil Engineering, vol. 21, pp. 339-345, 2017.View Article |
| [7] | M. Grzybowski and S. P. Shah, “Shrinkage cracking of fiber reinforced concrete,” Materials Journal, vol. 87, pp. 138-148, 1990.View Article |
| [8] | W. Dong, X. Zhou, and Z. Wu, “A fracture mechanics-based method for prediction of cracking of circular and elliptical concrete rings under restrained shrinkage,” Engineering Fracture Mechanics, vol. 131, pp. 687-701, 2014.View Article |
| [9] | C. A. Shaeles and K. C. Hover, “Influence of mix proportions and construction operations on plastic shrinkage cracking in thin slabs,” Materials Journal, vol. 85, pp. 495-504, 1988.View Article |
| [10] | K. Kovler, J. Sikuler, and A. Bentur, “Restrained shrinkage tests of fibre-reinforced concrete ring specimens: effect of core thermal expansion,” Materials and Structures, vol. 26, pp. 231-237, 1993.View Article |
| [11] | F. Collins and J. Sanjayan, “Cracking tendency of alkali-activated slag concrete subjected to restrained shrinkage,” Cement and Concrete Research, vol. 30, pp. 791-798, 2000.View Article |
| [12] | AASTHO, “Standard Practice for Estimating the Cracking Tendency of Concrete A Specification” in Designation: , ed. United States, 1997, pp. PP34-99, 1997. |
| [13] | X. Wei and Z. Li, “Early hydration process of Portland cement paste by electrical measurement,” Journal of materials in civil engineering, vol. 18, pp. 99-105, 2006.View Article |
| [14] | ASTM”C109-1998”. “Test method for compressive strength of hydraulic cement mortars (Using 2-in. or [50-mm] cube specimens),” vol. vol. 04.01, 1998. |
| [15] | C. ASTM, “403/403M-99 (1999) Standard test methods for time of setting of concrete mixtures by penetration resistance,” Annual book of ASTM standards, vol. 4, pp. 1-6, 1999. |
| [16] | B. S. Muazu, X. Wei, and L. Wang, “Hydration process and crack tendency of concrete based on resistivity and restrained shrinkage crack,” Journal of Wuhan University of Technology-Mater. Sci. Ed., vol. 31, pp. 1026-1030, 2016.View Article |
| [17] | Y. Liao, X. Wei, and G. Li, “Early hydration of calcium sulfoaluminate cement through electrical resistivity measurement and microstructure investigations,” Construction and building materials, vol. 25, pp. 1572-1579, 2011.View Article |
| [18] | X. Wei, L. Xiao, and Z. Li, “Electrical measurement to assess hydration process and the porosity formation,” Journal of Wuhan University of Technology--Materials Science Edition, vol. 23, pp. 761-766, 2008.View Article |
