







































Energy and Earth Science 
Vol. 2, No. 2, 2019 

www.scholink.org/ojs/index.php/ees 
ISSN 2578-1359 (Print)   ISSN 2578-1367 (Online) 

45 
 

Study on Effect of Superplasticizer on GGBS Blended 

Geopolymer Concrete 
Vahini M.1*, K. Manjunatha2, Venkatesh3 & Basappa Meti1**, 

1 Department of Civil Engineering, Government Engineering College, Haveri, India 
2 VTU Regional Office, Mysore, India 
3 Government Engineering College, Kushalnagara, India 
* Vahini M., E-mail: vahini_cta@yahoo.com;  

** Basappa Meti, E-mail: bsmeti@gmail.com 

 

Received: June 21, 2019   Accepted: July 9, 2019    Online Published: September 3, 2019 

doi:10.22158/ees.v2n2p45         URL: http://dx.doi.org/10.22158/ees.v2n2p45 

 
Abstract 

Geopolymer concrete is an alternate to conventional concrete with reduced carbon emission, embodied 

energy and global warming potential and transforming waste product into an useful material. 

Geopolymer concrete is produced by mixing highly alkaline activator solution with alumino silicate 

source materials. Geopolymer concrete is highly viscous or sticky in nature, to overcome this drawback, 

an attempt has been made to study the effect of naphthalene based superplasticizer on geopolymer 

concrete blended with GGBS. Fly ash was replaced by GGBS at 20% increment levels, keeping a 

constant superplasticizer dosage at 3% by weight of binding material. Workability and strength 

characteristics were compared with those of geopolymer concrete blended with GGBS without 

superplasticizer. Up to certain replacement level of fly ash with GGBS, results in decrease of strength 

parameters with increase in workability, further replacement results in increase of strength with 

reduced workability with the addition of superplasticizer. 

Keywords 

ground granulated blast furnace slag(GGBS), fly ash, superplasticizer, blended geopolymer concrete 

 

1. Introduction 

1.1 General 

Concrete is the widely used material in the world after water. Ordinary Portland cement has been used 

traditionally as a binding material for preparation of concrete. The world-wide consumption of concrete 

is believed to rise exponentially for the infrastructural development taking place in China and India. 

One tone of carbon dioxide is estimated to be released to the atmosphere when one ton of ordinary 

Portland cement is manufactured; also the emission by cement manufacturing process contributes 7% 



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to the global carbon dioxide emission. It is important to find an alternate binder which has less carbon 

footprint than cement. Geopolymer concrete is one such alternate binding material, wherein the cement 

is totally replaced by industrial byproducts such as fly ash, GGBS etc., with rich content of aluminium 

and silicon. Davidovits (1988; 1994) proposed that an alkaline liquid could be used to react with the 

Silicon (Si) and Aluminum (Al) in a source material of geological origin or in by product materials 

such as fly ash and GGBS to produce binders. Because the chemical reaction that takes place in this 

case is a polymerization process, he coined the term geopolymer to represent these binders. The final 

properties of geopolymer concrete is influenced by large number of factors like type of curing, water 

content, alkali concentration, solids content, silicate and aluminates ratio, pH and others. 

Geopolymer concrete is highly viscous or sticky in nature, which reduces the workability. To increase 

the workability, extra water or superplasticizer will be added. Therefore, the present work aims to study 

the effect of adding superplasticizer on workability and strength characteristics of GGBS blended 

geopolymer concrete. 

1.2 Constituents of Geopolymer Concrete 

Geopolymer concrete can be manufactured by using the low-calcium fly ash obtained from 

coal-burning power stations. Most of the fly ash available globally is low-calcium fly ash formed as a 

by-product of burning anthracite or bituminous coal. Although coal burning power plants are 

considered to be environmentally unfriendly, the extent of power generated by these plants is increasing 

due to the huge reserves of good quality coal available worldwide and the low cost of power produced 

from these sources. The energy returned-to-energy invested ratio of coal burning power plants is high, 

and second only to the hydro-power generation plants. (Lloyd, 2009) 

The main constituents of the geopolymer concrete are source materials and alkaline liquids. The source 

materials should be rich in silicon (si) and aluminum (Al), these could be natural materials such as 

kaolin, clays etc. Alternatively, by-product materials such as fly ash, silica fume, slag, rice husk ash, red 

mud etc. could be used as source materials. The choice of the source materials for making geopolymers 

depends on factors such as availability, cost, type of application, specific demand of the end users. The 

alkaline liquids are from soluble alkali metals that are usually sodium or potassium based. 

 

2. Literature Review 

Nuruddin et al. (2011) have studied the effect of superplasticizer (SP) dosage and molarity of NaOH 

solution on workability and compressive strength of Self-Compacting Geopolymer Concrete. The 

workability properties such as filling ability, passing ability and resistance to segregation were assessed 

using slump flow, T-50, V-funnel, L-Box and J-ring test methods. It was found that the essential 

workability requirements for self compactability were satisfied. Results show that low superplasticizer 

content 3, 4 and 5% had poor filling and passing ability and the workability results were not satisfied 

the limits of self compacting concrete. As the concentration of NaOH solution increased from 8M to 

12M, the compressive strength of geopolymer concrete has increased. They have concluded that 6% of 



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SP dosage and 12M of NaOH concentration as the optimum values.  

Laskar and Bhattacharjee (2012) have made an attempt to study variation of workability of fly ash 

based geopolymer concrete with the variation of lignin based plasticizer and polycarboxylic ether based 

superplasticizer. It has been observed that there exists a critical value of molar strength of sodium 

hydroxide beyond which superplasticizer and plasticizer have adverse effect on workability of fly ash 

based geopolymer concrete. Below the critical molar strength of sodium hydroxide, there is an increase 

in slump. Plasticizer and superplasticizer dosage improves workability of fly ash based geopolymer 

concrete for molar strength of NaOH solution less than 4M. Lignin based superplasticizer has been 

found to be more effective than PC based superplasticizer. 

Nematollahi and Sanjayan (2014) have presented a review on efficacy of available superplasticizers on 

geopolymers. The effect of SPs on workability, strength and rheological parameters (yield stress and 

plastic viscosity) of slag and fly ash based geopolymer paste, mortar and concrete was 

comprehensively reviewed in this study. In summary, research results reported in the literature ascertain 

that SPs do not work the same on geopolymer systems than in OPC systems. The effect of SPs on slag 

and fly ash based geopolymers directly depends on the type of binder and activators in addition to the 

type and dosage of the SPs as well as the pH of the alkaline solution. In general, the PC based SPs 

(latest generation) are the most effective type in the case of fly ash based geopolymer activated by 

NaOH +Na2SiO3 activators. Whereas, in the case of slag based geopolymers activated by NaOH 

solution, N based SPs (second generation) are the most efficient type. Moreover, in most cases using 

SPs might decrease the strength of the slag and fly ash based geopolymers with reference to the 

original geopolymers without using SP. 

Nematollahi and Sanjayan (2014) have evaluated the effect of different commercial superplasticizers 

(SPs) such as naphthalene, melamine and modified polycarboxylate based on the workability and 

strength of a class F fly ash geopolymer paste activated by two different activator combinations i.e., 8M 

sodium hydroxide solution and a multi-compound activator composed of 8M NaOH solution (28.6%) + 

Na2SiO3 (71.4%) with a SiO2/Na2O ratio of 2.0. These SPs at a dosage of 1% by mass of fly ash were 

added to the fresh paste and flowability of the activated fly ash paste measured via mini slump test and 

compared with that of paste without using any SP. The experimental results indicated that the effect of 

different SPs on the workability and strength of fly ash based geopolymer directly depends on the type 

of activator and the SP. In the case of using 8M NaOH solution as the activator, naphthalene based SP 

was an effective type; whereas modified polycarboxylate based SP was the most efficient type when the 

multi-compound activator was used. 

Xie and Kayali (2015) have investigated the use of superplasticizers with enhanced dispersion 

capability for different geopolymer pastes. Two types of polycarboxylate based and one type of 

naphthalene based superplasticizer were investigated. Results showed that all the applied 

superplasticizers were considerably less effective with geopolymers, a higher than usual dosage of 

superplasticizer was needed for noticeable workability enhancements. Naphthalene based 



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superplasticizers caused higher instantaneous slump and larger spread than polycarboxylate based type. 

 

3. Materials and Methodology 

3.1 Materials 

The alumino silicate material used in this study is a combination of fly ash and ground granulated blast 

furnace slag (GGBS). Fly ash is procured from Bellary thermal power plant, Kudithini. GGBS is 

obtained from JSW, Bellary. Sodium silicate and Sodium hydroxide are procured from Shree Chem, 

Bangalore and locally available coarse and fine aggregates are used. Table 1 shows the physical 

properties of materials used. Sodium hydroxide used is in flakes form with 97% purity, concentration of 

sodium silicate solution is 47.50% with Na2O 14.7% and SiO2 32.8%. Conplast SP 430 is used as 

Naphthalene based superplasticizer. 

 

Table 1. Physical Properties of Materials Used  

Material Fly ash GGBS Fine aggregate Coarse aggregate 

Specific Gravity 2.20 2.79 2.42 2.5 

 

3.2 Mix Proportions 

As there are no codal provisions for the mix design of geopolymer concrete, the geopolymer concrete 

mix was prepared as per the procedure given by Patankar et al. The alkaline liquid to fly ash ratio is 

kept as 0.35. The ratio of sodium hydroxide to sodium silicate is taken as 1.00 Concentration of sodium 

hydroxide solution is maintained as 13M. Mix design is carried out for M30 grade of geopolymer 

concrete. Quantity of materials required is shown in Table 2. 

 

Table 2. Quantity of Ingredients of M30 Geopolymer Concrete 

Ingredient of 

geopolymer 

concrete 

Fly 

ash 
NaOH Na2SiO3 Sand 

Coarse 

aggregate 

Total 

water 

Content 

Extra 

Water 

Quantity ( kg/m3) 405 70.875 70.875 686.81 1261.56 110 31.48 

 

3.3 Casting and Curing 

Fine aggregate, coarse aggregate, fly ash are mixed in dry condition for 3-4 minutes and then the 

alkaline solution, which is a combination of sodium hydroxide solution and sodium silicate solution 

with superplasticizer dosage of 3% by weight of binding material is added to the dry mix. Figure 1 

shows the casting of specimens. Specimens are demoulded after 24 hrs of casting and kept in ambient 

condition for curing as shown in Figure 2. 

 



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       Figure 1. Casting of Specimens        Figure 2. Specimens at Ambient Curing  

 

4. Results and Discussions 

The specimens are designated as FA100 for 100% fly ash and FGn for fly ash and GGBS blends at n% 

of fly ash. Fly ash is replaced at an increment of 20% by weight with GGBS. Workability and strength 

characteristics are studied for GGBS blended geopolymer concrete with and without SP. 

 

 

Figure 3. Slump for GGBS Blended Geopolymer Concrete with and without Superplasticizer 

 

Workability in terms of slump is shown in Figure 3. It is observed that the slump for geopolymer 

concrete with superplasticizer is more when compared with geopolymer concrete without 

superplasticizer, for all replacements of fly ash with GGBS. Slump for geopolymer concrete without 

superplasticizer, reduces with increase in GGBS level but for geopolymer concrete with 

superplasticizer, slump increases up to 40% replacement of fly ash with GGBS and then it decreases 

which may be due to the presence of calcium in GGBS. 

Strength properties such as compressive strength, split tensile strength and flexural strength are 

conducted for GGBS blended geopolymer concrete with and without superplasticizer and the results 

are shown in Table 3. 



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Table 3. Strength Properties of Geopolymer Concrete Blended with GGBS with and without 

Superplasticizer 

 

Specimen 

description 

Compressive Strength 

(MPa) 

Split Tensile Strength 

(MPa) 
Flexural Strength (MPa) 

Without 

Superplast

icizer 

With 

Superplast

icizer 

Without 

Superplast

icizer 

With 

Superplasti

cizer 

Without 

Superplasti

cizer 

With 

Superplasti

cizer 

FA 100 45.04 42.67 5.19 4.01 7.60 7.53 

FG 80 50.37 48.89 5.19 4.95 8.40 7.73 

FG 60 60.37 54.22 5.38 5.00 9.40 8.00 

FG 40 47.33 60.44 3.21 5.19 5.40 8.67 

FG 20 21.56 55.70 2.50 4.95 1.33 7.47 

 

Figure 4. Compressive Strength for GGBS Blended Geopolymer Concrete with and without 

Superplasticizer 

 



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Figure 5. Split Tensile Strength for GGBS Blended Geopolymer Concrete with and without 

Superplasticizer 

 

 
Figure 6. Flexural Strength for GGBS Blended Geopolymer Concrete with and without 

Superplasticizer 

 

Compressive strength, split tensile strength and flexural strength for GGBS blended geopolymer 

concrete with and without superplasticizer are shown in Figure 4 to 6 respectively. Upto 40% 

replacement of fly ash with GGBS, all strength parameters such as compressive strength, split tensile 

strength and flexural strength reduce with the addition of superplasticizer, when compared to 

geopolymer concrete without superplasticizer, due to unstability of superplasticizer in highly alkaline 

activator condition. Beyond 40% replacement, all strength parameters increase with the addition of 

superplasticizer due to reduced activator to slag ratio, which agrees with the past research. 



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5. Conclusions 

In this study the effect of naphthalene based superplasticizer on GGBS blended geopolymer concrete 

has been made. Based on the experimental results, following conclusions are drawn. 

• Workability increases with the addition of superplasticizer for all replacement levels of 

GGBS. Maximum of 40% increase in workability is observed for 40% replacement of fly ash 

with GGBS. 

• Strength properties are decreased by 20% upto 40% replacement level when superplasticizer 

is added. 

• Strength properties such as compressive strength reduces by 10%, split tensile strength 

reduces by 20% and flexural strength reduces by 20%, when fly ash is replaced upto 40% 

with GGBS with the addition of superplasticizer. 

• Strength properties are increased by 100 to 450% with the addition of superplasticizer beyond 

40% replacement level of fly ash with GGBS. 

• FG60 i.e., 60% fly ash + 40% GGBS is the optimum blend without superplasticizer and FG40 

i.e., 40% fly ash + 60% GGBS is the optimum blend with superplasticizer. 

 

References 

Carabba, L., Manzi, S., & Bignozzi, M. C. (2016). Superplasticizer Addition to Carbon Fly Ash 

Geopolymers Activated at Room Temperature. Materials, 9, 586. 

https://doi.org/10.3390/ma9070586 

Fadhil, N. M., Demie, S., Fareed, A. M., & Shafiq, N. (2011). Effect of Superplasticizer and NaOH 

Molarity on Workability, Compressive Strength and Microstructure Properties of Self-Compacting 

Geopolymer Concrete. International Journal of Civil and Environmental Engineering, 3(2), 

122-129. 

Laskar, A. I., & Bhattacharjee, R. (2012). Effect of Plasticizer and Superplasticizer on Workability of 

Fly Ash Based Geopolymer Concrete. Proceedings of International Conference on Advances in 

Architecture and Civil Engineering (AARCV 2012), 21st-23rd June 2012. 

Lloyd, N., & Rangan B. V. (2009). Geopolymer Concrete; Sustainable Cementless Concrete (pp. 

33-54). Proceeding of the 10th ACI International Conference on Recent Advances in Concrete 

Technology and Sustainability Issues , Seville, ACISP-261. 

Nematollahi, B., & Sanjayan, J. (2013). Effect of Superplasticizers on Workability of Fly Ash Based 

Geopolymer (pp. 713-719). In CIEC 2013, Proceedings of the International Civil and Infrastructure 

Engineering Conference. https://doi.org/10.1007/978-981-4585-02-6_61 

Nematollahi, B., & Sanjayan, J. (2014). Effect of different superplasticizers and activator combinations 

on workability and strength of fly ash based geopolymer concrete. Materials and Design, 57, 

667-672. https://doi.org/10.1016/j.matdes.2014.01.064 

https://doi.org/10.3390/ma9070586
https://doi.org/10.1007/978-981-4585-02-6_61
https://doi.org/10.1016/j.matdes.2014.01.064


www.scholink.org/ojs/index.php/ees                      Energy and Earth Science                     Vol. 2, No. 2, 2019 

53 
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Nematollahi, B., & Sanjayan, J. (2014). Efficacy of Available Superplasticizers on Geopolymers. 

Research Journal of Applied Sciences, Engineering and Technology, 7(7), 1278-1282. 

https://doi.org/10.19026/rjaset.7.420 

Patankar, S. V., Ghugal, Y. M., & Jamkar, S. S. (2015). Mix Design of Fly Ash Based Geopolymer 

Concrete. In Advances in Structural Engineering (pp 1619-1634). Springer India. 

https://doi.org/10.1007/978-81-322-2187-6_123 

Xie, J. T., & Kayali, O. (2015). Effect of superplasticizer on workability enhancement of class F fly 

ash- based geopolymers. 2015 world of coal ash(WOCA) conference in Naschille, TN- May 5-7. 

 

https://doi.org/10.19026/rjaset.7.420
https://doi.org/10.1007/978-81-322-2187-6_123

	Study on Effect of Superplasticizer on GGBS Blended Geopolymer Concrete
	Abstract
	Geopolymer concrete is an alternate to conventional concrete with reduced carbon emission, embodied energy and global warming potential and transforming waste product into an useful material. Geopolymer concrete is produced by mixing highly alkaline a...
	Keywords

	ground granulated blast furnace slag(GGBS), fly ash, superplasticizer, blended geopolymer concrete
	1.1 General
	Concrete is the widely used material in the world after water. Ordinary Portland cement has been used traditionally as a binding material for preparation of concrete. The world-wide consumption of concrete is believed to rise exponentially for the inf...
	Geopolymer concrete is highly viscous or sticky in nature, which reduces the workability. To increase the workability, extra water or superplasticizer will be added. Therefore, the present work aims to study the effect of adding superplasticizer on wo...
	1.2 Constituents of Geopolymer Concrete
	Geopolymer concrete can be manufactured by using the low-calcium fly ash obtained from coal-burning power stations. Most of the fly ash available globally is low-calcium fly ash formed as a by-product of burning anthracite or bituminous coal. Although...
	The main constituents of the geopolymer concrete are source materials and alkaline liquids. The source materials should be rich in silicon (si) and aluminum (Al), these could be natural materials such as kaolin, clays etc. Alternatively, by-product ma...
	3.1 Materials
	3.2 Mix Proportions
	As there are no codal provisions for the mix design of geopolymer concrete, the geopolymer concrete mix was prepared as per the procedure given by Patankar et al. The alkaline liquid to fly ash ratio is kept as 0.35. The ratio of sodium hydroxide to s...
	Table 2. Quantity of Ingredients of M30 Geopolymer Concrete
	3.3 Casting and Curing
	Fine aggregate, coarse aggregate, fly ash are mixed in dry condition for 3-4 minutes and then the alkaline solution, which is a combination of sodium hydroxide solution and sodium silicate solution with superplasticizer dosage of 3% by weight of bindi...

	References

