scholarly journals Residual expansion capacity and degradation of mechanical properties in alkali-silica reaction (ASR) damaged concrete

2019 ◽  
Author(s):  
Monica Ramsey ◽  
Stephanie Wood ◽  
Robert Moser
Keyword(s):  
Mechanical Properties ◽  
Alkali Silica Reaction ◽  
Degradation Of Mechanical Properties ◽  
Expansion Capacity

The Role of Alkalis in Hydraulic Mixtures

2019 ◽  
Vol 955 ◽  
pp. 62-67
Author(s):  
Lukáš Procházka ◽  
Jana Boháčová
Keyword(s):  
Mechanical Properties ◽  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Alkali Silica Reaction ◽  
Type Ii ◽  
Hydration Products ◽  
Experimental Part ◽  
Ph Values ◽  
Furnace Slag

Alkali substances are present in cements used as a binder in concrete only in a minimum content. The most known process that alkali causes is the alkali-silica reaction. In this reaction, the alkali contained in the cement or supplied from the outside with an inappropriately selected aggregate containing amorphous SiO2. This reaction results in the development of hydration products, resulting in an increase in the volume of the original components, which can cause a breakage of the concrete structure and subsequent disintegration. The range of alkali-silica reaction can be reduced by the use of a suitable aggregate or the use of Type II admixtures which are characterized by pozzolanic or latently hydraulic activity. These admixtures react with alkali and then no longer react with the amorphous SiO2 contained in the aggregate. Alkalis also affect other properties of concrete such as basic physical-mechanical properties, frost resistance and pH.In the experimental part the pH values were compared between mixtures of Portland cement and alkaline activated blast furnace slag using slag aggregate from the heap Koněv.

Mechanical properties of concrete with smeared cracking by alkali-silica reaction and freeze-thaw cycles

2020 ◽  
Vol 111 ◽  
pp. 103623
Author(s):  
Fuyuan Gong ◽  
Yuya Takahashi ◽  
Izuru Segawa ◽  
Koichi Maekawa
Keyword(s):  
Mechanical Properties ◽  
Alkali Silica Reaction ◽  
Freeze Thaw

Hydrogen-Related Degradation of Mechanical Properties of Titanium and Titanium Alloys

2009 ◽  
Vol 6 (1) ◽  
pp. 101853
Author(s):  
Kenzo Asaoka ◽  
Kunimitsu Maejima ◽  
Kenneth L. Jerina ◽  
Michael R. Mitchell ◽  
Terry O. Woods ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Titanium Alloys ◽  
Degradation Of Mechanical Properties

scholarly journals The degradation of mechanical properties in halloysite nanoclay–polyester nanocomposites exposed to diluted methanol

2016 ◽  
Vol 51 (11) ◽  
pp. 1653-1664 ◽  
Author(s):  
Mohd Shahneel Saharudin ◽  
Rasheed Atif ◽  
Islam Shyha ◽  
Fawad Inam
Keyword(s):  
Mechanical Properties ◽  
Impact Toughness ◽  
Degradation Of Mechanical Properties ◽  
Before And After ◽  
The Matrix ◽  
Methanol Exposure ◽  
The Impact ◽  
And Storage ◽  
Methanol System ◽  
Methanol Absorption

The degradation of mechanical properties in halloysite nanoclay–polyester nanocomposites was studied after an exposure of 24 h in diluted methanol system by clamping test specimens across steel templates. The glass transition temperature ( Tg) and storage modulus increased steadily with the increase of halloysite nanoclays before and after diluted methanol exposure. The addition of nano-fillers was found to reduce liquid uptake by 0.6% in case of 1 wt% reinforcement compared to monolithic polyester. The mechanical properties of polyester-based nanocomposites were found to decrease as a result of diluted methanol absorption. After diluted methanol exposure, the maximum microhardness, tensile, flexural and impact toughness values were observed at 1 wt% of halloysite nanoclay. The microhardness increased from 203 to 294 HV (45% increase). The Young’s modulus increased from 0.49 to 0.83 GPa (70% increase) and the tensile strength increased from 23 to 27 MPa (17.4% increase). The impact toughness increased from 0.19 to 0.54 kJ/m2 in diluted methanol system (184% increase). Surprisingly, the fracture toughness of all types of nanocomposites was found to increase after exposing to diluted methanol due to plasticization effect. Scanning electron microscope images of the fractured surfaces of tensile specimens revealed that the methanol increased the ductility of the matrix and reduced the mechanical properties of the nanocomposites.

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