Frost/salt scaling and ice formation of concrete: Effect of curing temperature and silica fume on normal and high strength concrete

1996 ◽  
pp. 103-116
Keyword(s):  
Silica Fume ◽  
High Strength Concrete ◽  
High Strength ◽  
Curing Temperature ◽  
Ice Formation ◽  
Strength Concrete ◽  
Salt Scaling

Effects of Nano-CaCO3 on the Compressive Strength and Microstructure of High Strength Concrete in Different Curing Temperature

2011 ◽  
Vol 121-126 ◽  
pp. 126-131 ◽  
Author(s):  
Qing Lei Xu ◽  
Tao Meng ◽  
Miao Zhou Huang
Keyword(s):  
Compressive Strength ◽  
Low Temperature ◽  
High Strength Concrete ◽  
High Strength ◽  
Curing Temperature ◽  
Test Results ◽  
Strength Concrete ◽  
Calcium Nitrite ◽  
Orientation Index ◽  
Early Strength

In this paper, effects of nano-CaCO3 on compressive strength and Microstructure of high strength concrete in standard curing temperature(21±1°C) and low curing temperature(6.5±1°C) was studied. In order to improve the early strength of the concrete in low temperature, the early strength agent calcium nitrite was added into. Test results indicated that 0.5% dosage of nano-CaCO3 could inhibit the effect of calcium nitrite as early strength agent, but 1% and 2% dosage of nano-CaCO3 could improve the strength of the concrete by 13% and 18% in standard curing temperature and by 17% and 14% in low curing temperature at the age of 3days. According to the XRD spectrum, with the dosage up to 1% to 2%, nano-CaCO3 can change the orientation index significantly, leading to the improvement of strength of concrete both in standard curing temperature and low curing temperature.

Effects of Silica Fume Addition on the Spalling Phenomena of Reactive Powder Concrete

2012 ◽  
Vol 174-177 ◽  
pp. 1090-1095 ◽  
Author(s):  
Kai Pei Tian ◽  
Yang Ju ◽  
Hong Bin Liu ◽  
Jin Hui Liu ◽  
Li Wang ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Vapor Pressure ◽  
Silica Fume ◽  
High Strength Concrete ◽  
High Strength ◽  
Reactive Powder Concrete ◽  
Spalling Resistance ◽  
Explosive Spalling ◽  
Strength Concrete ◽  
Reactive Powder

The explosive spalling of high-strength concrete due to fire is a problem that has garnered increasingly widespread attention, particularly the explosive spalling of reactive powder concrete (RPC). For years, based on the vapor pressure mechanism, the addition of fibers has been demonstrated to be somewhat effective in protecting against spalling. However, relevant experiments indicate that fibers are not effective for dense concrete, which is a challenge for the simple vapor pressure mechanism in providing spalling resistance for RPC. The authors found that silica fume plays an important role in the explosive spalling of RPC. Thus, four classes of RPCs with different ratios of silica fume were prepared, and the spalling phenomena and the inner temperature distribution during heating were investigated. The results show that silica fume content has a prominent effect on the spalling process of RPC.

Some characteristics of high-strength structural concrete

1991 ◽  
Vol 18 (5) ◽  
pp. 885-889 ◽  
Author(s):  
J. A. Bickley ◽  
J. Ryell ◽  
C. Rogers ◽  
R. D. Hooton
Keyword(s):  
Silica Fume ◽  
High Strength Concrete ◽  
High Performance ◽  
High Strength ◽  
Standard Test ◽  
Technical Note ◽  
Concrete Technology ◽  
Chloride Permeability ◽  
Strength Concrete ◽  
Low Humidity

The 68-storey Scotia Plaza tower in Toronto is an outstanding example of the use of concrete technology to achieve high-performance high-strength concrete. Cementitious hydraulic slag, silica fume, and a superplasticizer were combined with CSA type-10 Portland cement and high-quality aggregates to produce very workable high-strength concrete. During the course of construction, data were published suggesting the possibility of the strength regression of some silica fume concretes after long exposure to low humidity, the determinations being made on standard test cylinders. Tests were, therefore, made at ages of 1 year and 2 years on specimens drilled from columns in the structure. This technical note gives details of the laboratory examination and testing of these specimens. Key words: high strength, slag, silica fume, permeability, rapid chloride permeability, petrographic examination, superplasticizers.

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