scholarly journals The influence of concrete shrinkage on durability of reinforced structural members

2015 ◽  
Vol 63 (1) ◽  
pp. 15-22 ◽  
Author(s):  
K. Flaga
Keyword(s):  
Static Strength ◽  
Structural Members ◽  
Concrete Technology ◽  
Limit States ◽  
Important Distinction ◽  
Near Surface ◽  
Strength Performance ◽  
Concrete Shrinkage ◽  
Novel Approach ◽  
Macro Scale

Abstract The aim of the paper was to present the author’s novel approach to the problem of the influence of concrete shrinkage on the static-strength performance of reinforced structures. The problem of concrete shrinkage has been known in concrete technology for years, mainly in the theoretical and experimental aspects. However, there are few works in which the effect of concrete shrinkage in real reinforced structural members and structures is shown. In the present article the author performs an analysis of these effects on a macro-scale, useful in the assessment of the influence of concrete shrinkage on limit states of bearing capacity and serviceability of reinforced concrete structures. An important distinction is made between shrinkage stresses imposed in RC members by external and internal (reinforcement induced) constraints and residual shrinkage stresses inside members (massive especially) resulting from non-stationary and non-linear moisture fields. The article concludes with a way of calculating the necessary, near-surface anti-shrinkage reinforcement in such members.

scholarly journals Inclusion of CFRP-Epoxy Composite for End Anchorage in NSM-Epoxy Strengthened Beams

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Md. Akter Hosen ◽  
Mohd Zamin Jumaat ◽  
A. B. M. Saiful Islam
Keyword(s):  
Reinforced Concrete ◽  
Failure Modes ◽  
Concrete Cover ◽  
Structural Members ◽  
Premature Failure ◽  
Near Surface ◽  
Steel Bars ◽  
Near Surface Mounted ◽  
Separation Failure ◽  
Concrete Cover Separation

Nowadays, the use of near surface mounted (NSM) technique strengthening reinforced concrete (RC) structural members is going very popular. The failure modes of NSM strengthened reinforced concrete (RC) beams have been shown to be largely due to premature failure such as concrete cover separation. In this study, CFRP U-wrap end anchorage with CFRP fabrics was used to eliminate the concrete cover separation failure. A total of eight RC rectangular beam specimens of 125 mm width, 250 mm depth, and 2300 mm length were tested. One specimen was kept unstrengthened as a reference; three specimens were strengthened with NSM steel bars and the remaining four specimens were strengthened with NSM steel bars together with the U-wrap end anchorage. The experimental results showed that wrapped strengthened beams had higher flexural strength and superior ductility performance. The results also show that these beams had less deflection, strain, crack width, and spacing.

Correlation between near-surface electromagnetic soil parameters and early-time GPR signals: An experimental study

Geophysics ◽  
2007 ◽  
Vol 72 (2) ◽  
pp. A25-A28 ◽  
Author(s):  
Elena Pettinelli ◽  
Giuliano Vannaroni ◽  
Barbara Di Pasquo ◽  
Elisabetta Mattei ◽  
Andrea Di Matteo ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Early Time ◽  
Test Site ◽  
Time Domain Reflectometry ◽  
Soil Parameters ◽  
Time Interval ◽  
Near Surface ◽  
Novel Approach ◽  
Natural Test ◽  
Ground Penetrating

We explore a new approach to evaluate the effect of soil electromagnetic parameters on early-time ground-penetrating radar (GPR) signals. The analysis is performed in a time interval which contains the direct airwaves and ground waves, propagating between transmitting and receiving antennas. To perform the measurements we have selected a natural test site characterized by very strong lateral gradient of the soil electrical properties. To evaluate the effect of the subsoil permittivity and conductivity on the radar response we compare the envelope amplitude of the GPR signals received in the first [Formula: see text] within [Formula: see text]-wide windows, with the electrical properties ([Formula: see text] and [Formula: see text]) determined using time-domain reflectometry (TDR). The results show that the constitutive soil parameters strongly influence early-time signals, suggesting a novel approach for estimating the spatial variability of water content with GPR.

STRENGTH, SHRINKAGE, AND PERMEABILITY PERFORMANCE OF SEAWATER CONCRETE

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Adel Younis ◽  
Usama Ebead ◽  
Prannoy Suraneni ◽  
Antonio Nanni
Keyword(s):  
Experimental Program ◽  
Hardened Concrete ◽  
Chloride Permeability ◽  
Strength Performance ◽  
Sustainable Concrete ◽  
Concrete Shrinkage ◽  
Concrete Mixtures ◽  
Study Results ◽  
Compressive Strength Test ◽  
Global Concern

Given the increasing global concern of freshwater scarcity, the use of seawater in concrete mixtures appears to be a way forward towards achieving sustainable concrete, especially in the case of non-reinforced concrete applications or with the use of non-corrosive reinforcement. This paper reports on the results of an experimental study to compare the freshwater-and seawater-mixed concretes in terms of their strength, shrinkage and permeability performance. The experimental program included the following: (i) compressive strength test (at 3, 7, 28, and 56-day ages); (ii) concrete shrinkage test (at Days 4, 7, 14, 21, 28, and 56 following mixing); and (iii) permeability tests (rapid chloride permeability and water absorption at Days 28 and 56 following mixing). As for the study results, seawater concrete showed a slightly higher early-age (i.e., till Day 7) strength performance than that of freshwater-mixed counterpart, followed by a strength performance that is 7–10% inferior to the freshwater concrete after 28 days or later. Also, the shrinkage of seawater concrete was slightly higher than that of freshwater concrete, with a difference of 5% reported after 56 days following mixing. Finally, the permeability performance of hardened concrete in seawater and freshwater mixtures was similar.

Research of Polypropylene Concrete’s Pavement Performance

2014 ◽  
Vol 638-640 ◽  
pp. 1503-1507
Author(s):  
Ting Zhang ◽  
Yi Tang Zhou ◽  
Luo Ke Li ◽  
Xiu Ying Fan
Keyword(s):  
High Performance ◽  
High Efficiency ◽  
High Performance Concrete ◽  
Polypropylene Fiber ◽  
Pavement Performance ◽  
Concrete Technology ◽  
Synthetic Fibers ◽  
Concrete Shrinkage ◽  
Shrinkage Cracks ◽  
Major Development

Emergence of commodity concrete and pumping concrete is a major development of modern concrete technology, it has high efficiency, high homogeneity and good environmental effects, etc. But, use of modern high performance concrete make the difficulty of controlling the early cracks increased, considering this problem, use of polypropylene fibers to test concrete shrinkage cracks, come to regularity of polypropylene fiber affect concrete shrinkage cracks early, in order to serve the synthetic fibers used in concrete better.

Quantitative conductivity and permittivity estimation using full-waveform inversion of on-ground GPR data

Geophysics ◽  
2012 ◽  
Vol 77 (6) ◽  
pp. H79-H91 ◽  
Author(s):  
Sebastian Busch ◽  
Jan van der Kruk ◽  
Jutta Bikowski ◽  
Harry Vereecken
Keyword(s):  
Quantitative Estimation ◽  
Waveform Inversion ◽  
Measured Data ◽  
Optimization Approach ◽  
Full Waveform Inversion ◽  
Near Surface ◽  
Full Waveform ◽  
Novel Approach ◽  
Wide Range ◽  
Starting Model

Conventional ray-based techniques for analyzing common-midpoint (CMP) ground-penetrating radar (GPR) data use part of the measured data and simplified approximations of the reality to return qualitative results with limited spatial resolution. Whereas these methods can give reliable values for the permittivity of the subsurface by employing only the phase information, the far-field approximations used to estimate the conductivity of the ground are not valid for near-surface on-ground GPR, such that the estimated conductivity values are not representative for the area of investigation. Full-waveform inversion overcomes these limitations by using an accurate forward modeling and inverts significant parts of the measured data to return reliable quantitative estimates of permittivity and conductivity. Here, we developed a full-waveform inversion scheme that uses a 3D frequency-domain solution of Maxwell’s equations for a horizontally layered subsurface. Although a straightforward full-waveform inversion is relatively independent of the permittivity starting model, inaccuracies in the conductivity starting model result in erroneous effective wavelet amplitudes and therefore in erroneous inversion results, because the conductivity and wavelet amplitudes are coupled. Therefore, the permittivity and conductivity are updated together with the phase and the amplitude of the source wavelet with a gradient-free optimization approach. This novel full-waveform inversion is applied to synthetic and measured CMP data. In the case of synthetic single layered and waveguide data, where the starting model differs significantly from the true model parameter, we were able to reconstruct the obtained model properties and the effective source wavelet. For measured waveguide data, different starting values returned the same wavelet and quantitative permittivities and conductivities. This novel approach enables the quantitative estimation of permittivity and conductivity for the same sensing volume and enables an improved characterization for a wide range of applications.

A novel approach to estimating near‐surface S‐wave velocity and converted‐wave receiver statics

2009 ◽  
Author(s):  
Rishi Bansal ◽  
Warren Ross ◽  
Sunwoong Lee ◽  
Mike Matheney ◽  
Alex Martinez ◽  
...  
Keyword(s):  
Wave Velocity ◽  
S Wave ◽  
Converted Wave ◽  
Near Surface ◽  
Novel Approach

scholarly journals Effect of Corrosion on Static Strength of Hull Structural Members (1st Report)

2002 ◽  
Vol 2002 (192) ◽  
pp. 357-365 ◽  
Author(s):  
Hisao Matsushita ◽  
Tatsuro Nakai ◽  
Norio Yamamoto ◽  
Hironori Arai
Keyword(s):  
Static Strength ◽  
Structural Members

scholarly journals Effect of Corrosion on Static Strength of Hull Structural Members (3rd Report)

2004 ◽  
Vol 2004 (195) ◽  
pp. 233-242 ◽  
Author(s):  
Tatsuro Nakai ◽  
Hisao Matsushita ◽  
Norio Yamamoto
Keyword(s):  
Static Strength ◽  
Structural Members

scholarly journals Effect of Corrosion on Static Strength of Hull Structural Members (5th Report)

2004 ◽  
Vol 2004 (196) ◽  
pp. 161-168 ◽  
Author(s):  
Tatsuro Nakai ◽  
Hisao Matsushita ◽  
Norio Yamamoto
Keyword(s):  
Static Strength ◽  
Structural Members
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