05-07-2014, 10:56 AM
MODIFIED GUIDELINES FOR GEOPOLYMER CONCRETE MIX DESIGN USING INDIAN STANDARD
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ABSTRACT
This experimental study is intended to identify the mix ratios for different grades of
Geopolymer Concrete by trial and error method. A new Design procedure was formulated for
Geopolymer Concrete which was relevant to Indian standard (IS 10262-2009). The
applicability of existing Mix Design was examined with the Geopolymer Concrete. Two kinds
of systems were considered in this study using 100% replacement of cement by ASTM class
F flyash and 100% replacement of sand by M-sand. It was analyzed from the test result that
the Indian standard mix design itself can be used for the Geopolymer Concrete with some
modification.
INTRODUCTION
Geopolymers are inorganic polymeric materials with a chemical composition similar to zeolites but
possessing an amorphous structure. Geopolymers may be seen as man-made rocks. They can be
produced by reacting solid aluminosilicates with a highly concentrated aqueous alkali hydroxide or
silicate solution. The chemistry and terminology of inorganic polymers was first discussed in detail
by Davidovits [1]. Since the first mention of the term ‘geopolymer’ by Davidovits [1],
Geopolymers form three-dimensional disordered frameworks of the tecto-aluminosilicate type with
the general empirical formula Mn[-(SiO2)z-AlO2]n.wH2O, in which n is the degree of
polycondensation, and M is predominantly a monovalent cation (K+, Na+), although Ca2+ may
replace twomonovalent cations in the structure [2].
The present work is carried out in the framework of a project aims to produce the
geopolymeric Mix procedure of different grade of geopolymer concrete matrices, stronger and
denser equal to the cement concrete obtained by using Portland Cement binders, that can be
MATERIALS USED
Cementitious material used in this Experimental programme was low calcium Flyash (ASTM
type F) [2]. The specific gravity Fly Ash was 2.3. The Specific gravity and Fineness modules
for manufactured sand were 3.1 and 2.15 respectively. The chemical composition for
cementitious material is shown in table 3. Locally available crushed granite stone aggregate of
size 20 mm passing and retained in 10 mm, was used and the specific gravity and fineness
modulus for the same are 2.6 and 6.4 as per IS: 2386- 1968 Part III. Both the Aggregates
compiled with the requirements of IS: 383-1970.Specific gravity of NaoH and Na2Sio3
solutions were 1.47 and 1.6 respectively.
DESIGN OF GEOPOLYMER CONCRETE MIXTURES
Data for mix design
The following basic data are required to be specified for design of a concrete mix:
a) Characteristic compressive strength of Geopolymer Concrete at 24 hours curing at the
temperature of 60ºC (fck).
b) Maximum size and Type of Fine aggregate and Coarse Aggregate to be used.
c) Specific gravity of ingredients of concrete.
d) Selection of Alkaline liquid, Flyash Ratio to the Compressive ratio.
Aggregates size, grading, surface texture, shape and other characteristics may produce
secretes of different compressive strength for the same tiled ratio, the relationship between
strength and free Alkaline liquid, Extra Water, Fly ash Ratio should preferably be established
for the materials [7,8,9].
3.2 Estimation of air content
Approximate amount of entrapped air to be expected in normal (non-air-entrained) concrete is
given in Table 6
ILLUSTRATIVE EXAMPLE FOR GEOPOLYMER CONCRETE MIX DESIGN
An example illustrating the mix design for a Geopolymer concrete of M 30 grade is given
below:
4.1 Design stipulations
a) Characteristic compressive strength required at age of
36hours at the temperature of 60ºC
= 30MPa
b) Maximum size of aggregate (angular) = 10mm
c) Specific gravity of fly ash = 2.3
d) Specific gravity of coarse aggregate = 2.6
e) Specific gravity of fine aggregate = 3.1
f) Sand conforming = zone III
g) Specific gravity of NaOH = 1.47
CONCLUSION
With the generic information available on geopolymers, a rigorous trial-and-error method
was adopted to develop a process of manufacturing fly ash-based geopolymer concrete
following the technology currently used to manufacture Ordinary Portland Cement
concrete. After some failures in the beginning, the trail-and-error method yielded
successful results with regard to manufacture of low-calcium (ASTM Class F) fly ashbased
geopolymer concrete.
· Geopolymer concrete is an excellent alternative solution to the CO2 producing port land
cement concrete.
· Low-calcium fly ash-based geopolymer concrete has excellent compressive strength
within a day and is suitable for structural applications [10].
· The price of fly ash-based geopolymer concrete is estimated to be about 10 to30
percent cheaper than that of Portland cement concrete.
· In this study it is observed that Compressive strength results obtained for M-sand was
nearly equal when compared to control concrete.