Strength Correlation and Prediction of Engineered Cementitious Composites with Microwave Properties

Abstract

This paper presents the results of microwave and mechanical measurements of engineered cementitious composites (ECCs) using a nondestructive microwave near-field detecting technique. The objective of this research is to investigate the correlations between effective conductance and compressive strength of ECCs at various curing ages under the influence of different initial water contents. Parallel measurements and regression analysis on compressive strength and microwave conductance were undertaken. It is shown that the strength evolution of ECCs can be accurately modeled and predicted by using microwave conductance at the early ages using bi-exponential functions. Compressive strength grows as a function of decreasing effective conductance, whereas the regression coefficients of the correlation models have a linear variation with water-to-binder ratios. These findings have highlighted the effectiveness of the microwave technique in detecting the variation of liquid phase morphology and pore structure.

Microwave Non-Destructive Inspection and Prediction of Modulus of Rupture and Modulus of Elasticity of Engineered Cementitious Composites (ECCs) Using Dual-Frequency Correlation

“…In this study, a standard mix design with a water-to-binder ( w / b ) ratio of 0.255 according to the initiative proposed by Li et al [ 33 , 34 , 35 ] was adopted. In addition, two more ECC mixes with slightly decreased ( w / b = 0.20) and increased ( w / b = 0.30) initial water contents were cast in order to investigate the effects of small variation in w / b ratio to the microwave [ 30 ] and mechanical properties. The values of all mix proportions of ECC composites are summarized in Table 3 , where the proportions of PVA fiber at a standard volume fraction of 2% (26 kg/m 3 ) remain constant.…”

“…These include the rebound hammer test [ 1 ], the use of embedded sensors [ 2 , 3 , 4 , 5 ], the ultrasonic approaches [ 6 , 7 , 8 , 9 ], the acoustic methods [ 10 ], the electrical resistance or resistivity tests [ 11 , 12 , 13 , 14 , 15 ], the microwave non-destructive inspection/monitoring (mNDI) techniques [ 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 ]. Recently using electromagnetic or microwave approaches as a NDI method has been gaining more attention especially for concrete structures [ 24 , 25 , 26 , 27 , 28 , 29 , 30 ]. Microwave signals can penetrate inside a dielectric medium (e.g., CBMs) and interact with its microstructure.…”

“…Mubarak et al [ 19 ] developed a simple robust on-site mNDI technique for determining w / b of CBMs. Whilst Peer et al [ 21 ] used reflection and dielectric properties for investigating effects of chloride and cyclical exposure to it in mortar, Chung et al [ 30 ] developed correlation models to predict the compressive strength of ECCs with microwave conductance. Moreover, the mNDI techniques offer advantage of inspecting the desired structure without direct contact in cases where physical access is not possible, for example, CBMs exposed to high temperatures.…”

MEMS Inertial Sensor for Strata Stability Monitoring in Underground Mining: An Experimental Study

“…Microseismic (MS) monitoring technique, with remarkable advantages in terms of real time, three-dimensional positioning of mechanical breaking events, has been successfully utilized in underground mining [1][2][3], powerhouse cavern [4], tunnels [5,6], and oil and gas extraction [7,8]. Electrical resistivity tomography [9,10], acoustic Emission [11], synthetic aperture radar interferometry [12], and many other advanced technologies such as the microwave nondestructive inspection technique [13,14] were also applied in strength prediction and underground excavation engineering. Those monitoring techniques do make a great contribution for the underground excavation monitoring; however the large scale, complex, and costly monitoring facilities may be the obstacles of applying monitoring system in universal application.…”

Structural Health Monitoring (SHM) of Civil Structures

“…Popular terms such as Internet of Things and smart structures were coined as a result of the intersection between advances in other engineering disciplines with civil engineering to produce the new field of structural health monitoring (SHM). The field of SHM is now at a vital crossroads, where researchers are challenged to develop technologies for the monitoring and retrofit of older buildings and at the same time to push the boundaries of SHM through the creative use of cutting-edge technologies and data processing algorithms.This issue is a snapshot of the newest research in SHM for civil structures, and it includes a range of topics such as data processing algorithms to detect damage, modeling, and simulation [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]; sensor development and experiments [16][17][18][19][20][21][22][23][24][25][26]; materials studies [27,28]; state-of-the-art reviews [29,30]; and case studies [31]. SHM is highly multi-disciplinary, and advances in other areas of study can likely be recruited for the progress of SHM.…”