ABSTRACT – Usage of Ground granulated blast furnace slag(GGBS) and silica fume(SF) in the blended concrete alongside ordinary portland cement(OPC) has been in practice owing to low cost of production, denser microstructure leading to enhanced durability with satisfactory strength properties of concrete. The present study focusses on usage of GGBS and Silica Fume in ternary blended mortars. 1:4 and 1:6 mortars are studied for compressive strength at 3,7, and 28 days of age. Results indicated that compressive strength of mortar cubes was at par with that of control mix upto mixes with 30% GGBS and 10% Silica Fume. Cost analysis indicated a decrease in cost of binder from the mixes with 30% GGBS and 10% Silica Fume in comparison with control mix. Keywords- GGBS, M-Sand, Silica Fume, Blended Mortar, Compressive strength

1. Experimental investigation on ternary blended cement mortars
Abdul Razak B H1
and D L Venkatesh Babu2
1
Research Scholar, Department of Civil Engineering, ACS College of Engineering, Bengaluru,
Karnataka, India, Contact Number: 9743064727, Email: abdulrazak.b.h@gmail.com,
Orcid ID: 0000-0003-1874-3120
2
Research Supervisor, Department of Civil Engineering, ACS College of Engineering,
Bengaluru, Karnataka, India, Email: drdlvbabu@gmail.com
ABSTRACT – Usage of Ground granulated blast furnace slag(GGBS) and silica fume(SF) in
the blended concrete alongside ordinary portland cement(OPC) has been in practice owing to
low cost of production, denser microstructure leading to enhanced durability with satisfactory
strength properties of concrete. The present study focusses on usage of GGBS and Silica Fume in
ternary blended mortars. 1:4 and 1:6 mortars are studied for compressive strength at 3,7, and 28
days of age. Results indicated that compressive strength of mortar cubes was at par with that of
control mix upto mixes with 30% GGBS and 10% Silica Fume. Cost analysis indicated a
decrease in cost of binder from the mixes with 30% GGBS and 10% Silica Fume in comparison
with control mix.
Keywords- GGBS, M-Sand, Silica Fume, Blended Mortar, Compressive strength
INTRODUCTION
Supplementary cementitious materials such as GGBS, Silica Fume, Fly ash have become the
integral part of concrete and mortar over the decades. GGBS has been utilized in mortars to a
greater extent. GGBS along with Silica Fume and OPC have resulted in denser microstructure
along with satisfactory compressive strength of mortar[1]. Studies on effect of drying on blended
cement mortars containing Fly Ash/GGBS as binder with OPC have been carried out. Flexural
strength, fracture toughness were tested for the specimens. Drying was reported to increase
flexural strength and fracture toughness. Mineral admixtures had negligible influence on these
test parameters[2]. Mortars containing Silica Fume and slag exhibit higher autogenous
deformation in comparison with mortars containing Type F Fly ash[3]. Blended mortars exhibit
compressive and flexural strength than that of control mix due to their higher porosity[4].
Metakaoline and Silica Fume improve compressive strength in mortars before and after exposure
to elevated temperature[5]. Usage of incinerated bottom ash in mortars decreased compressive
strength and flowability properties. However the IBA manufactured from the process of melting
enhanced the properties of mortar in by decreasing capillary pores in mortar which are evident
from the microstructural study[6]. GGBS, Fly Ash and undensified silica fume were used as
replacement for OPC upto 50% in mortar. Results indicated that absorption and volume of
permeable pore space increased in blended mortar at 28 days with increasing Silica Fume
content. Water cured specimens showed increase in compressive strength with increase in curing
temperature. The drying shrinkage of all the blended mixes was lower than that of control mix.
However, the specimens containing higher silica fume and cured with plastic sealed and water at
250 C showed higher drying shrinkage in comparison with the control specimen[7]. Decrease in
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2. compressive and flexural strength of nano-metakaolin mortar specimens was observed when
exposed to temperatures above 2500 C[8].
Mortars containing nano-metakaolin indicated higher compressive strength in comparison with
fly ash blended cement mortar at 60 days of hydration[9]. Durability properties of mortars
partially exposed to sulfate attack indicated that upper part of the specimen which was not in
direct contact of chemical suffered physical attack. Fly ash in mortar contributed for resistance
for chemical attack better than GGBS[10].
MATERIALS AND METHODOLOGY
The materials used in the study include Ordinary Portland cement (C), GGBS(S), and Silica
Fume(SF).
Table 1 Chemical analysis and properties of cement and mineral additives
Cement GGBS Silica fume
Moisture 0.26 0.51 -
L.O.I. 1.22 2.80 -
SiO2 20.90 37.90 96.90
CaO 61.65 38.75 0.50
Al2O3 5.20 6.90 0.20
Fe2O3 3.30 1.10 -
MgO 2.60 8.70 0.38
SO3 2.90 2.40 -
Density (kg/m3
) 3100 2750 2145
Specific surface area:
BET (m2
/ kg) 14500
BLAINE (m2
/ kg) 370 202 -
Table 2 Specific Gravity of mortar ingredients
Ingredient Specific Gravity
OPC 3.10
GGBS 2.85
Silica Fume 2.2
Manufactured Sand 2.50
Methodology
1.Study on characteristics mortar ingredients.
2.Mix design of ternary blended mortars.
3.Study on strength properties of ternary blended mortars
EXPERIMENTAL WORK
The following experimental works have been carried out:
1. Tests on concrete ingredients such as specific gravity test.
2. Chemical analysis and properties of cement and mineral additives
3. Mix Design of ternary blended mortar mixes.
4. Determination of compressive strength of ternary blended mortar mixes at 3,7, and 28
days of curing.
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3. Table 3 Mix codes for the mortar mixes
Binders Mix Designation
100% OPC C100
80% OPC + 10% GGBS + 10% SF C80G10S10
70% OPC + 20% GGBS + 10% SF C70G20S10
60% OPC + 30% GGBS + 10% SF C60G30S10
50% OPC + 40% GGBS + 10% SF C50G40S10
40% OPC + 50% GGBS + 10% SF C40G50S10
30% OPC + 60% GGBS + 10% SF C30G60S10
Fig 1 Cost Analysis of binder
RESULTS AND DISCUSSIONS
A. Compressive strength of mortar blocks (1:4)
Sl.No. Mix
Weight of
Specimen, kg
Average 3-Days
Compressive
Strength, N/mm²
Average 7-Days
Compressive
Strength, N/mm²
Average 28-Days
Compressive
Strength, N/mm²
1 C100 778 28.30 42.40 65.20
2 C80G10S10 758 23.50 35.20 63.20
3 C70G20S10 746 21.10 31.60 62.2
4 C60G30S10 752 19.00 28.50 60.8
5 C50G40S10 738 17.10 25.60 39.40
6 C40G50S10 748 15.40 23.10 35.50
7 C30G60S10 755 13.80 20.70 31.80
0 100 200 300 400 500
C100
C80G10S10
C70G20S10
C60G30S10
C50G40S10
C40G50S10
C30G60S10
Cost of Binder, Rs./50 kg
Mortar
Mix
Cost Analysis of Binder
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4. B.Compressive Strength of Mortar blocks (1:6)
Sl.No. Mix
Weight of
Specimen, kg
Average 3-Days
Compressive
Strength, N/mm²
Average 7-Days
Compressive
Strength, N/mm²
Average 28-Days
Compressive
Strength, N/mm²
1 C100 801 27.30 40.90 62.90
2 C80G10S10 782 23.50 38.50 63.1
3 C70G20S10 793 21.50 35.10 62.80
4 C60G30S10 771 16.60 27.30 42.00
5 C50G40S10 747 12.30 20.10 31.00
6 C40G50S10 763 10.80 18.40 28.30
7 C30G60S10 740 8.50 14.80 22.80
CONCLUSION
 Reduction in cost of mortar can be achieved at replacement of OPC beyond 30%.
 Compressive strength of 1:4 mortar blocks upto 40% replacement of OPC shows very
less reduction in comparison with control mix at 28 days. Strength decreases for mortar
blocks thereafter.
 Compressive strength of 1:6 mortar blocks decreases with increase in GGBS content at 3
and 7 days strength.
28-day compressive strength of 1:6 mortar blocks with 10% and 20% GGBS with 10%
Silica Fume exhibit similar value in comparison with control mix. For mixes with OPC
replacement beyond 30%, the compressive strength of mortar deceases by 33%.
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