Using Eccentrically Sample to Find the Relationship between Resistivity and Cracking Time in Cement Paste Vides Mechanical Strength and Electrical Resistivity

Maha. A. Abusogi¹, WEI Xiaosheng^1, and Fu lei¹

¹School of Civil Engineering and Mechanics, Huazhong University of Science and Technology, Wuhan, China

Cite this paper:
Maha. A. Abusogi, WEI Xiaosheng and Fu lei. Using Eccentrically Sample to Find the Relationship between Resistivity and Cracking Time in Cement Paste Vides Mechanical Strength and Electrical Resistivity. American Journal of Civil Engineering and Architecture. 2017; 5(4):154-159. doi: 10.12691/ajcea-5-4-3

Abstract

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).

Keywords:
eccentrically steel cracking frame eccentrically restrained cracking test eccentrically restrained shrinkage test

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