scholarly journals EVALUATION OF CONCRETE RESISTANCE TO CHLORIDE IONS PENETRATION BY MEANS OF ELECTRIC RESISTIVITY MONITORING

2005 ◽  
Vol 11 (2) ◽  
pp. 109-114 ◽  
Author(s):  
Marta Kosior-Kazberuk ◽  
Walery Jezierski
Keyword(s):  
Portland Cement ◽  
Salt Solution ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Chloride Salt ◽  
Test Results ◽  
Ion Permeability ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Concrete Resistivity

The chloride‐induced corrosion of reinforcing steel is the major reason for the premature deterioration and degradation of field concrete structures built in a salt‐laden environment. The results of investigation of the bituminous addition effect on Portland cement concrete resistance to chloride ions penetration are presented in this paper. Chloride penetration was simulated by subjecting samples to cyclic loading with salt solution and drying. Concrete resistivity development was monitored during 12 months. The test results have been analysed to verify the effect of addition content, the time of exposure in aggressive environment, as well as the sort of cement on chloride ion permeability of Portland cement concrete. The statistical analysis showed that bituminous addition significantly improves the concrete resistance to chloride salt solution penetration.

Chloride Ion Diffusion of Phosphoaluminate Cement Concrete

2009 ◽  
Vol 79-82 ◽  
pp. 99-102 ◽  
Author(s):  
Zhu Ding ◽  
Feng Xing ◽  
Ming Zhang ◽  
Peng Liu
Keyword(s):  
Portland Cement ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Hydration Products ◽  
Portland Cement Concrete ◽  
Ion Diffusion ◽  
Cement Concrete ◽  
Dense Microstructure ◽  
Corrosion Of Steel ◽  
Chloride Ion Diffusion

Penetration and diffusion of chloride ions in concrete can lead to the corrosion of steel bar and shorten the service life of concrete structures. Phosphoaluminate cement (PAC) is a new cementitious material which has many special properties compared to Portland cement (PC). In the study, chloride ion diffusion in PAC concrete was tested with RCM method. The phase composition and morphology of hydration products, pore volume of hardened paste cured for 28d were analyzed with X-ray diffraction (XRD) and mercury intrusion porosimetry (MIP). The results show that chloride ion diffusion coefficient of PAC concrete is much lower than that of Portland cement concrete under the same test conditions. The hydration products of PAC are main micro-crystalline phase and gel of phosphate and/or phophoaluminate, which formed a dense microstructure. There is no calcium hydroxide produced in the PAC hydration system. In hardened PAC paste, chloride ions might replace the atom group [OH] - and [PO4]3- of hydrates and become stable compounds. The resistance to chloride ion diffusion of PAC concrete will increase with the hydration age, because its microstructure becomes denser with the hydration age increasing.

scholarly journals Some Mechanical Properties of Cement Treated Base (CTB) Incorporating Waste Portland Cement Concrete Under Different Corresponding Conditions

2018 ◽  
Vol 7 (4.37) ◽  
pp. 138
Author(s):  
Asst. Prof. Dr. Khawla H. H. Shubber ◽  
Eng. Sajjad Hashim Mohamed
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Portland Cement ◽  
Granular Materials ◽  
Compression Strength ◽  
Cement Content ◽  
Strength Increase ◽  
Test Results ◽  
Portland Cement Concrete ◽  
Cement Concrete

This research represents a trial of understanding and improving mechanical properties of base or subbase granular materials, used in pavement construction, stabilized with Portland cement known as cement treated base (CTB) in terms of density, optimum water content (O.W.C), and compression Strength of three curing ages (3, 7, 28) days under different situations. Different Portland cement percent of (0, 5, 7, 10, 12, and 15) % by weight were added to selected base course granular materials (type B according to local standard specification in Iraq). Results showed that the density of mixture increase with increasing added cement percent, while O.W.C takes its maximum value around 7% cement content, and compression strength increase with increasing cement content and curing age. Then effect of replacing 50% of natural granular materials by waste Portland cement concrete (WPCC) was investigated on the results of (0, 7& 15)% cement content on density, O.W.C and compression strength in the three curing ages. Results reveled although density of mixture cooperating WPCC for 0% cement content was higher, CTB of natural granular material were denser. On the other hand compressive strength decrease in case of using WPCC for all percent cement added and curing ages. Finally, effect of soaking in water on CTB with (7 &15)% cement compressive strength of three curing ages was studied, under three period of soaking (1 week, 2 weeks, &one month). Test results exposed that, CTB Compressive strength increase with increasing soaking period but still less than that of un-soaked and for all curing ages. For each test stage mathematics relationships with acceptable correlation were presented proofing test results tendency.  

scholarly journals Behavior of Geopolymer Concrete Confined by Circular Hoops

2018 ◽  
Vol 159 ◽  
pp. 01018
Author(s):  
Muslikh ◽  
N. K. Anggraini ◽  
D. Hardjito ◽  
Antonius
Keyword(s):  
Portland Cement ◽  
Concrete Cover ◽  
Geopolymer Concrete ◽  
Test Results ◽  
Portland Cement Concrete ◽  
Reinforcing Bars ◽  
Cement Concrete ◽  
Conventional Concrete ◽  
K Value ◽  
Steel Bar

This paper discusses the behavior of geopolymer concrete subjected to passive confinement under compression loads. The confinement is induced by the use of lateral hoops, assembled from un-deformed reinforcing bars. To compare the effect of confinement, identical specimens were produced using conventional concrete with the similar concrete compressive strength. The cylinder specimens were 100 mm in diameter and 200 mm in height, and the hoops were placed on the outer most fibers of the cylinders, perpendicular to the line of loading, with no concrete cover. The parameters analyzed in this study were the steel bar to concrete volumetric ratio, the hoop spacings and the steel yield stresses. The experimental results show that unconfined geopolymer concrete were very brittle compared to the unconfined Portland cement concrete. The strength enhancement (K value) of the confined geopolymer concrete was higher than K value of Portland cement concrete. Confined geopolymer concrete also has better deformability compared to the confined Portland cement concrete. The average confinement effectiveness of geopolymer concrete also has a higher value than that commonly used in the Indonesian Concrete Standard (SNI), that is 4.1. The results were further assessed to the most recent experimental test results conducted in this area.

Development of Performance Specifications for Shrinkage of Portland Cement Concrete

2003 ◽  
Vol 1834 (1) ◽  
pp. 40-47 ◽  
Author(s):  
David W. Mokarem ◽  
Richard E. Weyers ◽  
D. Stephen Lane
Keyword(s):  
Portland Cement ◽  
Prediction Models ◽  
Drying Shrinkage ◽  
Chloride Ions ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Volume Changes ◽  
Code Model ◽  
Concrete Mixtures ◽  
Performance Specifications

During its service life, concrete experiences volume changes. One of the types of deformation experienced by concrete is shrinkage. There are four main types of shrinkage associated with concrete: plastic, autogenous, carbonation, and drying shrinkage. The volume changes in concrete from shrinkage can lead to the cracking of the concrete. In the case of reinforced concrete, cracks in the cover concrete provide a direct path for chloride ions to reach and corrode the reinforcing steel. The development of concrete drying-shrinkage performance specifications with an associated test procedure was assessed for concrete mixtures purchased by the Virginia Department of Transportation (VDOT). Five existing shrinkage-prediction models were also assessed to determine the accuracy and precision of each model as it pertains to the VDOT mixtures used in this study. The five models are the ACI 209 Code model, CEB90 Code model, Bazant B3 model, Gardner–Lockman model, and Sakata model. The percentage length change limits for the portland cement concrete mixtures were found to be 0.0300% at 28 days and 0.0400% at 90 days. The CEB90 Code model was judged as the best prediction model for the VDOT portland cement concrete mixtures.

Study on Chloride Penetration Resistance of High Volume Slag Powder Concrete

2014 ◽  
Vol 584-586 ◽  
pp. 1005-1010
Author(s):  
Hong Xia Ding ◽  
Chun Tao Wang ◽  
Bin Ge ◽  
Yun Sheng Li
Keyword(s):  
Portland Cement ◽  
Chloride Ion ◽  
High Volume ◽  
Penetration Resistance ◽  
Chloride Penetration ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Slag Powder ◽  
Chloride Penetration Resistance ◽  
Electric Flux

The influences of Portland cement substituted by slag powder in a high proportion (50% and 70%) on the chloride penetration resistance of concrete were studied. The results show that: the penetrability of Portland cement concrete reduced by one grade if 0.5% water reducer is added, but the water binder ratio is not the decisive factor for the permeability. There is a negative correlation between 6h electric flux and compressive strength only when concrete with same cementing materials. High volume slag powder concrete has excellent resistance to chloride ion permeability, which declines further with the increment of slag powder quantity added, the permeability coefficient of the concrete with 50% and 70% content of slag powder is as low as 27.8%~32.3% that of Portland cement concrete.

The Dynamic Elastic Modulus and Microstructure Study of High Performance Concrete in Sulfate Environment

2010 ◽  
Vol 113-116 ◽  
pp. 1371-1374 ◽  
Author(s):  
Hong Xia Qiao ◽  
Hong Fa Yu ◽  
Zhong Mao He
Keyword(s):  
Portland Cement ◽  
High Performance ◽  
Elastic Moduli ◽  
High Performance Concrete ◽  
Fine Aggregate ◽  
Test Results ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Sulfate Solutions ◽  
Better Than

Aimed at determining the durability of concrete in very salty regions, this paper describes a study carried out to examine the performance of various high performance fine aggregate concrete in a sulfate environment, such as high performance concrete inside a composite additive, and Portland cement concrete, and sulfate resistant cement concrete. They experienced dry-wet cycles in sodium sulfate solutions. By examining the changes of elastic moduli and analyzing the SEM of the concrete, the test results show that the salt resistances of sulfate resistant cement concrete is no better than Portland cement concrete in the extremely aggressive dry-wet cycle environment, and high performance concrete containing a composite additive has better resistance to a sulfate environment. Besides, the composite additive can create the environment for a second hydration to reduce the amount of Ca(OH)2 inside the concrete, and build additional C-S-H gel to reform the microstructure of concrete effectively. Finally, the paper offers some advice for mixing concrete in salt regions.

Development of a Capacitor Probe to Detect Subsurface Deterioration in Concrete

1997 ◽  
Vol 503 ◽  
Author(s):  
B. K. Diefenderfer ◽  
I. L. Al-Qadi ◽  
J. J. Yoho ◽  
S. M. Riad ◽  
A. Loulizi
Keyword(s):  
Dielectric Constant ◽  
Portland Cement ◽  
Electromagnetic Waves ◽  
Low Cost ◽  
Complex Dielectric Constant ◽  
Life Cycle Costs ◽  
Parallel Plates ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Set Up

ABSTRACTPortland cement concrete (PCC) structures deteriorate with age and need to be maintained or replaced. Early detection of deterioration in PCC (e.g., alkali-silica reaction, freeze/thaw damage, or chloride presence) can lead to significant reductions in maintenance costs. However, it is often too late to perform low-cost preventative maintenance by the time deterioration becomes evident. By developing techniques that would enable civil engineers to evaluate PCC structures and detect deterioration at early stages (without causing further damage), optimization of life-cycle costs of the constructed facility and minimization of disturbance to the facility users can be achieved.Nondestructive evaluation (NDE) methods are potentially one of the most useful techniques ever developed for assessing constructed facilities. They are noninvasive and can be performed rapidly. Portland cement concrete can be nondestructively evaluated by electrically characterizing its complex dielectric constant. The real part of the dielectric constant depicts the velocity of electromagnetic waves in PCC. The imaginary part, termed the “loss factor,” describes the conductivity of PCC and the attenuation of electromagnetic waves.Dielectric properties of PCC have been investigated in a laboratory setting using a parallel plate capacitor operating in the frequency range of 0.1 to 40.1MIHz. This capacitor set-up consists of two horizontal-parallel plates with an adjustable separation for insertion of a dielectric specimen (PCC). While useful in research, this approach is not practical for field implementation. A new capacitor probe has been developed which consists of two plates, located within the same horizontal plane, for placement upon the specimen to be tested. Preliminary results show that this technique is feasible and results are promising; further testing and evaluation is currently underway.

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