Literature Review
Sustainable Concrete: Investigating the utilization of industrial by-products in Cement kiln dust (CKD)
Ronald E. McNair Program
Dr. Sulapha Peethamparan
Clarkson University, Potsdam NY, 13699
Due to the production of cement a large amount of 𝐶𝑂2 is generated. The environmental effect of
manufacturing cement has become a leading concern of the construction industry and society as a whole.
A great emphasis has been place on producing concrete mixtures that incorporate industrial by-products
such as High volume fly ash (HVFA), Ground granulated blast furnace slag (GGBFS),and Cement kiln
dust (CKD). Fly ash (FA) is a waste material produced from combustion of coal in thermal power plants.
GGBFS is a by- product of the steel industry and CKD is a by-product of cement industry. A significant
amount of research has been conducted on the development of a binding material that can reduce the
production of cement as whole. Many researchers have focus on the use of CKD as an activator for
GGBFS or FA [1-5].
As a result, of the relatively high alkaline content in CKD it is not recycled in cement production.
However, it was observed that depending on the water-soluble alkali and sulfate compounds, CKD could
activate materials such as GGBFS. Since there are different sources of slag and CKD all were
characterized and compared in terms of the rates of heat evolution and strength development, hydration
products, and time of initial setting. A study of the effects of the influencing factors in terms of soluble
alkali content, particle size, and free lime content was undertaken. The results confirmed that CKD can
be successfully utilized to activate GGBFS. Since the binding material had an overall good performances
in temperature rise, setting time and mechanical [3].
Another type of research was conducted using CKD with the addition of NaOH and FA at different
curing temperatures over a study period of 100 days. Binding material were composed of 50% CKD and
50% FA, having 0, 2, and 5% NaOH addition, and cured at temperatures of 24, 38, and 50 °C were
evaluated. The binders were examined by Thermogravimetric analysis (TGA) and X-ray diffraction
(XRD) tests which indicate that the major crystalline hydration product of the CKD and FA binders is
ettringite. Ettringite is a mineral composed of hydrous basic calcium and aluminum sulfate. Ettringite is
stable in the CKD and FA system at age over 100 days. Results also show that curing at elevated
temperature is more effective for CKD and FA binder strength improvement than NaOH addition. At a
proper curing temperature of 38 °C, with a small addition of 2% NaOH there is increase in CKD and FA
binder strength. However, at a high curing temperature 50 °C and addition of 2% NaOH a reduction in the
binder strength occurred [4].
Although, research has been providing great alternatives then the used of cement; problems have
occurred with the setting time of the new binding materials. This persistent problem results in long
delays in finishing the concrete in the field. One researcher has discovered that the addition of (5%)
calcium hydroxide power or (5-10%) rapid set cement can significantly reduce the setting time using a
high volume fly ash (HVFA). HVFA concretes can be designed and produced to meet 28 days strength
requirements and often even exceed the durability performance of conventional concretes. Rheological
measurements and conventional Vicat setting time studies were conducted to verify that these powder
additions do indeed reduce setting times in paste systems based on both ASTM Class C and ASTM Class
F fly ashes. The reductions depend on the class of fly ash and suggest that trial mixtures would be a
necessity to apply these technologies to each specific fly ash/cement/admixture combination being
employed in the field. Potentially, for such screening studies, the rheological measurement of yield stress
may provide a faster indication of setting than conventional Vicat needle penetration measurements on
pastes [5].
Sustainability is a leading concern of society and research is conducted to change the environmental
effects caused by the production of cement. Research had proven that the used of industrial by- products
can reduce the production of cement. The use of CKD as an activator in FA or GGBFS along with other
chemical powders to produce a alternative non conventional cement, can help reduce the carbon footprint.
References:
[1] Piyush Chaunsali and Sulapha Peethamparan, Evolution of strength,
microstructure and mineralogical composition of cement kiln dust activated
ground granulated blast furnace slag Transp. Res. Rec.
[2] S. Peethamparan, J. Olek and J. Lovell, Influence of chemical and physical
characteristic of cement kiln dusts (CKDs) on their hydration behavior and
potential application in soil stabilization, Cem. Concr. Res. 38 (2008) 803-815.
[3] M. S. Konsta-Gdoutos and S. P. Shah, Hydration and properties of novel blended
cements based on cement kiln dust and blast furnace slag, Cem. Concr. Res. 33
(2003) 1269-1276.
[4] Kenji Wang, Surendra P. Shah, and Alexander Mishulovich, Effect of curing
temperature and NaOH addition on hydration and strength development of
clinker- free CKD_ fly ash binders, Cem.Concr. Res. 34 (2004) 299-309.
[5] Dale Bentz, and Chiara F. Ferraris, Rheology and setting of high volume fly ash
mixtures,Cem. Concr. Comp. 32 (2010) 265-270.
[6] ASTM C 191-1, Standard Test Methods for Time of Setting of Hydraulic Cement
by Vicat Needle, ASTM International, Pennsylvania.