Microstructural Study of Different Types of Very High Strength Concretes

1986 ◽  
Vol 85 ◽  
Author(s):  
Pierre-Claude Aitcin ◽  
Shondeep L. Sarkar ◽  
Yaya Diatta
Keyword(s):  
Silica Fume ◽  
High Strength Concrete ◽  
High Strength ◽  
Surface Cracks ◽  
Cement Type ◽  
Normal Concrete ◽  
Microstructural Study ◽  
Different Types ◽  
Early Strength ◽  
Very High

ABSTRACTVery high strength concretes with water-cement ratios ranging from 0.21 to 0.27, having compressive strengths varying between 73 and 118 MPa, were prepared. One series was made with only high early strength cement (Type III), and the other series contained 6% to 11% silica fume.In general, the microstructure of very high strength concrete is very dense and is composed mainly of C-S-H in the gel and crystalline phases. Mg, Al, S, Cl, K and Fe were detected in a number of C-S-H locales. The Ca/Si ratio was variable. In concretes without silica fume, the CH content is much lower than in normal concrete, and in the silica fume concretes it is still lower and not well crystallized. A few large, partly reacted and unreacted silica fume particles with surface cracks were present.Strong cement-aggregate bonding is seen in concretes with silica fume containing limestone aggregates, whereas the gravel concretes show microcracks and a weaker bonding.

Synergistic Roles of Slag and Silica Fume in Very High-Strength Concrete

1990 ◽  
Vol 12 (1) ◽  
pp. 32 ◽  
Author(s):  
PK Mehta ◽  
S Sarkar ◽  
P-C Aitcin ◽  
H Djellouli
Keyword(s):  
Silica Fume ◽  
High Strength Concrete ◽  
High Strength ◽  
Strength Concrete ◽  
Very High

Microstructural Study of Aggregate/Hydrated Paste Interface in Very High Strength River Gravel Concretes

1987 ◽  
Vol 114 ◽  
Author(s):  
Shondeep L. Sarkar ◽  
Yaya Diatta ◽  
Pierre-Claude Aïtcin
Keyword(s):  
Compressive Strength ◽  
Silica Fume ◽  
High Strength ◽  
Hydrated Lime ◽  
Excellent Correlation ◽  
Correlation Index ◽  
Microstructural Study ◽  
Weakest Link ◽  
Very High ◽  
Microstructural Examination

ABSTRACTThe aggregate/hydrated paste interface represents the weakest link in very high strength river gravel concrete, due to the surface smoothness of these aggregates.Microstructural examination of the aggregate/hydrated paste interface in four different (very low W/C ratio) very high strength concretes with and without silica fume shows major differences in the nature of the transition zone at the interface level. In the non-silica fume concretes, hydrated lime and ettringite are found quite exclusively at the interface, while in silica fume concretes, only C-S-H is observed.The modulus of elasticity can be correlated to the compressive strength by the equation, , with a low correlation index (78%) for non-silica fume concrete, whereas in silica fume concrete it becomes MPa, with excellent correlation in ex of 95%.These results can be explained by the nature of the aggregate/hydrated paste interface, which is stronger in silica fume concrete.

scholarly journals REACTIVE POWDER CONCRETE DENGAN SUMBER SILIKA DARI LIMBAH BAHAN ORGANIK

Teras Jurnal ◽  
2017 ◽  
Vol 3 (2) ◽  
pp. 157
Author(s):  
Yulius Rief Alkhaly
Keyword(s):  
Silica Fume ◽  
High Strength Concrete ◽  
High Performance ◽  
High Strength ◽  
Reactive Powder Concrete ◽  
Normal Concrete ◽  
Green Concrete ◽  
Strength Concrete ◽  
Reactive Powder

<p>Reactive powder concrete (RPC) merupakan varian baru dari beton mutu ultra tingggi (ultra high strength concrete) yang diperkenalkan kepada umum pertama kali pada tahun 1994. Beton modern ini memiliki beberapa keunggulan dibandingkan beton konvensional (normal concrete) atau beton kinerja tinggi (high performance concretes). Penelitian tentang RPC di Indonesi masih sangat terbatas, RPC pertama bermaterial lokal Indonesia dikembangkan tahun 2009, dengan sumber silika berasal dari silica fume. Sebagai bagian dari berbagai penelitian lanjutan tentang RPC, hasil akhir dari riset ini diharapkan dapat menghasilkan RPC yang benar-benar sesuai dengan karakteristik material di Indonesia. Sumber silika yang digunakan berasal dari limbah bahan organik sehingga dapat menekan biaya produksi dan menghasilan green concrete yang dapat mengurangi dampak negatif limbah terhadap lingkungan.</p><p><strong>Kata kunci:</strong> Reactive Powder Concrete, Silika, Limbah Bahan Organik</p>

Very High Strength Cement for Very High Strength Concrete

1984 ◽  
Vol 42 ◽  
Author(s):  
Pierre-Claude Aftcin ◽  
Claude Bédard ◽  
M. A. Sc. Marc Plumat ◽  
Gilbert Haddad
Keyword(s):  
Portland Cement ◽  
Silica Fume ◽  
High Strength Concrete ◽  
Coarse Aggregate ◽  
High Strength ◽  
Concrete Column ◽  
Ordinary Type ◽  
High Building ◽  
Very High

AbstractDuring 1984 summer, an experimental concrete column was cast in a 26-story high-building using a 100 MPa silica fume concrete. Only the coarse aggregate was selected specifically for this concrete. The cement used was an ordinary type 1 Portland cement. The superplasticizer was a naphthalene base. The field conditions were among the most unfavourable, the transportation was about 3/4 of an hour. The placing lasted 15 minutes. However, after 1 h 00 the slump of this concrete having a water/cementitious ratio of 0.25 was still higher than 100 mm so that the concrete was placed without any problems.

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.

Cropped Steel Fiber Reinforced Chemically Bonded Ceramic (CBC) Composites

1987 ◽  
Vol 114 ◽  
Author(s):  
Sean Wise ◽  
Kevan Jones ◽  
Claudio Herzfeld ◽  
David D. Double
Keyword(s):  
Silica Fume ◽  
Steel Fiber ◽  
High Strength ◽  
Cement Matrix ◽  
Metal Fiber ◽  
Morphological Form ◽  
The Matrix ◽  
Compressive And Flexural Strengths ◽  
Equivalent Properties ◽  
Very High

ABSTRACTVery high strength castable chemically bonded ceramic (CBC) materials have been prepared which consist of finely chopped steel fibers and steel aggregate in a silica modified portland cement matrix. This paper examines the effect of metal fiber addition on compressive and flexural strengths. The overall chemistry of the matrix is held constant but the morphological form of silica used and the cure conditions are altered to examine their effect. Compressive strengths in excess of 500 MPa and flexural strengths in excess of 80 MPa can be obtained.It is found that flexural strength increases proportionally with fiber content over the range of 0 to 10% by volume. Compressive strengths are not affected. Use of silica fume in the mixes produces higher strengths at low temperatures than mixes which contain only crystalline silica. High temperature curing/drying (400°C), which produces the highest strengths, produces equivalent properties for formulations with and without silica fume. Higher water/cement ratios are found to reduce compressive strengths but have relatively little effect on the flexural properties.

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