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ASSIGNMENT-IV

Properties of Structural Materials

Submitted to Dr. M. Burhan Sharif

Sajjad Qaiser

2010-MS-CES-15

Civil Engineering DepartmentUniversity of Engineering & Technology Lahore


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SAJJAD QAISER 2010-MS-CES-15

QUALITIES OF FLY ASH BEING USED IN CONCRETE AS INVESTIGATED

BY DIFFERENT RESEARCHERS IN THE RECENT PAST

One of the Journals presents the results from expansion tests on concrete prisms and mortar bars

containing reactive aggregate and different types and levels of fly ash. Eighteen fly ashes

representing those commercially available in North America were tested. The results showed that

the chemical composition of fly ash provided a reasonable indication of its performance in

physical expansion tests but could not be used to predict accurately, the degree of expansion or

the minimum safe level of fly ash required to suppress expansion to an acceptable limit. [1]

A study has been undertaken to investigate the effects of replacing large volumes of cement

(up to 75% by weight) on the properties of foamed concrete, with both graded and ungraded fly

ash. This brought out the conclusion that, only on the results of the compressive strength of

concrete cured under sealed conditions showed that, up to 67% of the cement could be replaced

without any significant reductions in the strength of concrete. There appeared to be an

insignificant difference in the performance of ungraded and the graded fly ashes used in this

investigation. [2]

A research presents study on the mechanical properties and durability of concrete made with a

high-volume fly ash (HVFA) blended cement using a coarse fly ash that did not meet the

fineness requirement of ASTM C 618. The sorted out results were compared with those of the

HVFA concrete in which un-ground fly ash had been added to the concrete. The properties of the

fresh concrete as well as that of the hardened concrete were investigated. The results showed that

the concrete made with this blended cement was superior to the concrete in which the un-ground

fly ash and the cement had been added separately at the mixer. The production of HVFA blended

cements, therefore, offered an effective way for the utilization of coarse fly ashes that did nototherwise meet the fineness requirements defined by standards. [3]

The performance of the concrete made with high-volume fly ash (HVFA) blended cements using

fly ashes from Canada and USA was evaluated. The investigated parameters comprised of the

compressive strength of concrete and its resistance to chloride ion penetration. Regardless of the


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type of the fly ash used, the concrete made with the HVFA blended cements developed higher

compressive strength at all ages than that of the HVFA concrete in which un-ground fly ashes

and laboratory produced portland cements had been added separately at the concrete mixer. The

increase in the compressive strength was more significant for the HVFA blended cements

produced with the cement without a super-plasticizer and made with coarse fly ash. The use of

HVFA blended cements improved the resistance of the concrete to chloride ion penetration and

the improvement in the resistance increased with an increase in the inter-grinding time of fly ash

and cement. Also the diffusion coefficient of chloride ion increased with the rise of the water to

binder ratio and decreases with the rise of quantity of fly ash. [4, 5]

The addition of fly ash and an expansive agent to the concrete of CFTs or a thin layer of fly ash

to the interface between steel tube and concrete (CFTFCs) to improve the compressive strength

and the bond strength of CFTs was experimentally investigated. The results showed that the

expansive concrete-filled steel tubular columns (CFETs) have the highest bond strength and

compressive strength at the age of 7 days and CFTFCs have higher bond strength and

compressive strength than fly ash concrete-filled steel tubular columns (CFFTs), which in turn

are higher than CFTs. However, both bond strength and compressive strength of CFTFCs

become the highest at the age of 28 days. [6]

The carbonation, corrosion of steel reinforcement in concrete and corrosion resistance of

concrete, incorporating large volumes of low quality fly ash (LVLQFA), were studied. The effect

of concentration of carbon dioxide used in the experiment on estimating the carbonation

resistance of LVLQFA concrete was also investigated. Test results showed that the LVLQFA

concrete with an activator had good carbonation and corrosion resistances to steel reinforcement.

The corrosion resistance of LVLQFA concrete was better than that of the control concrete. [7]


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REFERENCES

[1] Medhat H. Shehata, Michael D.A. Thomas, The effect of fly ash composition on the expansion of concrete

due to alkali silica reaction, Department of Civil Engineering, University of Toronto. Received 27 July

1999; accepted 13 April 2000.

[2] E.P. Kearsley, P.J. Wainwright, The effect of high fly ash content on the compressive strength of foamedconcrete, Department of Civil Engineering, University Pretoria, South Africa. Received 26 June 2000;

accepted 18 September 2000.

[3] N. Bouzoubaa, M.H. Zhang, V.M. Malhotra, Mechanical properties and durability of concrete made with

high-volume fly ash blended cements using a coarse fly ash, International Centre for Sustainable

Development of Cement and Concrete (ICON), CANMET/Natural Resources Canada. Received 2 August

1999; accepted 25 June 2001.

[4] N. Bouzoubaa, M.H. Zhang, V.M. Malhotra, Laboratory-produced high-volume fly ash blended cements

Compressive strength and resistance to the chloride-ion penetration of concrete, International Centre for

Sustainable Development of Cement and Concrete (ICON), CANMET/Natural Resources Canada.

Received 2 June 1999; accepted 21 April 2000.

[5] Faguang Leng, Naiqian Feng, Xinying Lu, An experimental study on the properties of resistance to

diffusion of chloride ions of fly ash and blast furnace slag concrete, Department of Civil Engineering,

Tsinghua University, China. Received 25 October 1999; accepted 6 March 2000.

[6] Gengying Li, Xiaohua Zhao, Liqiang Chen, Improve the strength of concrete-filled steel tubular columns

by the use of fly ash, Department of Civil Engineering, Shantou University, China. Received 1 May 2002;

accepted 24 October 2002.

[7] Linhua Jiang, Zhenqing Liu, Yiqun Ye, Durability of concrete incorporating large volumes of low quality

fly ash, Department of Materials Science and Engineering, Hohai University, China. Received 8 August

2003; accepted 30 December 2003

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