scholarly journals Effectiveness of two field methods of saturating near surface concrete on the water permeability of in situ concrete

2019 ◽  
Vol 289 ◽  
pp. 06004
Author(s):  
Kai Yang ◽  
Muhammed Basheer ◽  
Sreejith Nanukuttan ◽  
Yun Bai ◽  
Adrian Long
Keyword(s):  
Water Permeability ◽  
Electrical Resistance ◽  
Surface Region ◽  
Test Results ◽  
Permeability Test ◽  
Field Methods ◽  
Near Surface ◽  
Vacuum Saturation ◽  
Electrical Resistance Measurements

Determining the water permeability of concrete in structures remains a challenge because of difficulties in removing the influence of its moisture content. Saturating concrete with water could be one option, but this is not easy to achieve on site. This paper reports a testing programme carried out to assess the reliability and effectiveness of two field saturation methods, viz. vacuum saturation and ponding. The water permeability test results after applying the vacuum saturation and ponding were compared with that obtained after incremental immersion. It was found that ponding was unable to remove the influence of moisture, whilst vacuum saturation was effective for wet concretes. The results obtained from the electrical resistance measurements after incremental immersion suggested that the water permeability of concretes can be accurately determined by carrying out in situ permeability tests if the near surface region up to a depth of 25 mm is fully saturated.

Nanoscale Mechanical Properties of In-Situ Tribofilms Generated from ZDDP and F-ZDDP with and without Antioxidants

2007 ◽  
Vol 7 (12) ◽  
pp. 4378-4390 ◽  
Author(s):  
Anuradha Somayaji ◽  
Ramoun Mourhatch ◽  
Pranesh B. Aswath
Keyword(s):  
Electron Microscopy ◽  
Wear Debris ◽  
Surface Region ◽  
Nucleation And Growth ◽  
Near Surface ◽  
Transmission Electron ◽  
Dialkyl Dithiophosphates ◽  
Wear Tests ◽  
Diphenyl Amine

Tribofilms with thickness ranging from 100–200 nm were developed in-situ during wear tests using a zinc dialkyl dithiophosphates (ZDDP) and fluorinated ZDDP (F-ZDDP). The influence of the antioxidant alkylated diphenyl amine on the formation and properties of these tribofilm is examined. Results indicate that the thickness of the tribofilms formed when F-ZDDP is used is always thicker than the tribofilm formed with ZDDP. In addition, in the presence of antioxidants the tribofilm thickness is increased. The hardness of these tribofilms in the absence of the antioxidants is significantly higher at the near surface region (0–30 nm) when compared to the films formed in the presence of antioxidant. Nanoscratch tests conducted to examine the abrasion resistance of the tribofilms also indicate that the tribofilms formed by F-ZDDP are more resistant to scratch compared to films formed by ZDDP. In the presence of antioxidant, tribofilms formed by F-ZDDP are significantly thicker while both films behave in a similar fashion in nanoscratch tests. Transmission electron microscopy of the wear debris formed during the tests were examined and results indicate the nucleation and growth of nanoparticles of Fe3O4 with an approximate size of 5–10 nm embedded within an otherwise amorphous tribofilm.

Characterization of Phase Transitions Occurring in Solution Treated Ti-15Mo during Heating by Thermal Expansion and Electrical Resistance Measurements

2016 ◽  
Vol 879 ◽  
pp. 2318-2323 ◽  
Author(s):  
Pavel Zháňal ◽  
Petr Harcuba ◽  
Michal Hájek ◽  
Jana Šmilauerová ◽  
Jozef Veselý ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Titanium Alloy ◽  
Phase Transitions ◽  
Electrical Resistance ◽  
Temperature Changes ◽  
Solution Treated ◽  
Electrical Resistance Measurements ◽  
Ongoing Phase

Metastable β titanium alloy Ti-15Mo was investigated in this study. In-situ electrical resistance and thermal expansion measurements conducted on solution treated material revealed influence of ongoing phase transitions on measured properties. The monotonicity of the dependence of electrical resistance on temperature changes at 225, 365 and 560 °C The thermal expansion deviates from linearity between 305 and 580 °C.

STRENGTHENING OF PRESTRESSED HOLLOW CORE SLABS WITH OPENINGS USING NSM-CFRP STRIPS

2016 ◽  
Vol 3 (1) ◽  
Author(s):  
Karam Mahmoud ◽  
Steven Foubert ◽  
Ehab El-Salakawy
Keyword(s):  
Original Structure ◽  
Test Results ◽  
Hollow Core ◽  
Near Surface ◽  
Reinforced Polymer ◽  
Industrial Buildings ◽  
Near Surface Mounted ◽  
Parking Garages ◽  
Strengthening Technique

Precast, prestressed, hollow-core (HC) slabs are extensively used in many structures such as parking garages, commercial and industrial buildings. It is common for such structures to undergo changes while still in service, which may result in a reduction of their strength. One of these changes is to add in-situ openings at different locations along the slab to accommodate services such as intake/exhaust ducts or utility conduits. Near surface mounted (NSM) strengthening technique has proved to be an adequate technique that can be employed to restore or enhance the performance of the original structure. In this paper, the effect of openings and the efficiency of using NSM carbon fiber reinforced polymer (CFRP) strips as strengthening technique are investigated. A total of three full-scale prestressed HC slabs were tested; one without opening, one with an opening in the pure flexural zone and one with strengthened opening. Test results showed the presence of opening along the flexure span had a significant adverse effect on the post-cracking flexural stiffness, cracking load and the ultimate capacity of the slab. However, strengthening the opening with two strips of NSM-CFRP effectively enhanced the post-cracking stiffness, increased the ductility of the member and restored the flexural strength deficit incurred as a result of cutting the opening, and provided a net increase in flexural capacity.

In situ X-ray diffraction study of stacking fault formation in the near-surface region of transformation induced plasticity steels

2013 ◽  
Vol 530 ◽  
pp. 105-112 ◽  
Author(s):  
David Rafaja ◽  
Christina Krbetschek ◽  
Daria Borisova ◽  
Gerhard Schreiber ◽  
Volker Klemm
Keyword(s):  
Diffraction Study ◽  
Surface Region ◽  
Stacking Fault ◽  
X Ray Diffraction ◽  
Near Surface ◽  
Transformation Induced Plasticity ◽  
X Ray

Durability evaluation of concrete made of fly ash and copper slag

2021 ◽  
Author(s):  
Yousef Zandi
Keyword(s):  
Fly Ash ◽  
Water Permeability ◽  
Environmental Conditions ◽  
Electrical Resistance ◽  
Copper Slag ◽  
Resistance Test ◽  
Power Relationship ◽  
Good Precision ◽  
Permeability Test ◽  
Water Penetration

AbstractIn this paper, to improve the durability of concrete, fly ash has been used as a percentage of cement and copper slag rather than a percentage of sand. Using a resistance test and water permeability test, four series of concrete specimens containing fly ash and copper slag, each containing 49 concrete mixing designs, were evaluated. After obtaining the results, eight samples with the highest electrical resistance were selected and the specimens were again tested in different environmental conditions. The results show that the environmental conditions of sulfate and carbonate have the least and most impact on reducing durability and there is a power relationship, with good precision, between the water penetration of the test specimens and the electrical resistance of the test specimens.

scholarly journals In situ XRD measurements to explore phase formation in the near surface region

2019 ◽  
Vol 126 (20) ◽  
pp. 200901 ◽  
Author(s):  
Darina Manova ◽  
Stephan Mändl
Keyword(s):  
Phase Formation ◽  
Surface Region ◽  
Near Surface ◽  
In Situ Xrd
Sign in / Sign up

Export Citation Format

Share Document