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1. Introduction
The development of self-compacting concrete represents a big
step towards efficiency and working conditions at construction sites
and in the prefabricated buildings industry. Such material enables
shorter concreting times, better finish of the concrete surface, as
well as better characteristics in the hardened state, thus generat-
ing more durable structures (GRUNEWALD, 2004 [5]).
The benefits of SCC go beyond durability and resistance. Its use
reduces noise pollution, since it does not call for the use of vibra-
tors, which also contributes to lower electrical energy consump-
tion. The use of SCC also minimizes the risk of accidents caused
by an excessive number of people upon the slabs, since it requires
less manpower. It also reduces ergonomic problems which affect
workers, since the effort made in the launch and finish is smaller.
According to Tutikian (2007 [3]), the use of SCC steers construc-
tion services towards more industrialized production by reducing
manpower cost, increasing quality, durability, confidence in the
structure and workers’ security.
SCC can be considered the most significant achievement in con-
crete technology in decades, and it should gradually replace part
of the conventional concrete which is currently produced. SCC is a
material which boasts a unique combination of performance and uni-
formity, requirements which cannot be reached through the use of
regular conventional construction components (SONEBI 2004 [6]).
Tutikian (2007 [3]) states that the interest SCC has attracted in
Brazil is increasing, and it has been used in the prefabricated build-
ings industry as well as in current special constructions. However,
the main studies focus on its mechanical properties, durability and
possibility of use with specific types of local materials. Dosage,
which is one of the key aspects of this material, has only been
studied superficially.
SCC is more widely used in Japan and in Europe. In Brazil, howev-
er, a higher level of confidence in the methods of dosage is neces-
sary in order to make SCC more reliable and widespread, thus al-
lowing bigger possibilities for its application anywhere that proves
to be economically feasible (TÉCHNE MAGAZINE, 2008 [7]).
Several international and national procedures or recommendations
for SCC dosage have been issued as studies have become more
consistent. Such methods might differ in criteria for the definition
of granular composition, such as the amount of fine materials, the
setting of limits for the water/cement ratio, paste volume, amount
of superplasticizer admixture, the use of viscosity modifying ad-
mixture and separate studies of paste and mortar. Some methods
also consist of sequences of calculations, which translate into limit
intervals for each material in the mixture.
This study compares three existing methods of dosage for SCC with
local materials in order to determine which one is the most economi-
cal, sensible and durable, thus assisting the executor in making a
decision and providing economical and technical feasibility for prac-
tical applications, while also expanding the knowledge about SCC
as well as its use. The methods of dosage chosen were the one
proposed by Nan Su et al. [1], from 2001, for it is based on equations
and empirical calculations; the one by Repette-Melo [2], developed
in 2005, for it proposes a sequence of tests from the admixture in
the paste to the concrete for the adjustment of the components in
the mixture; the one by Tutikian & Dal Molin [3], developed in 2007,
for it studies the granular skeleton of concrete before making it self-
compacting. The self-compactibility of SCC in the fresh state was
compared through tests such as flow,
t500mm
, “L-box” and “V-funnel”
based on the limits defined by ABNT NBR 15823:2010 [4]. In the
hardened state, the characteristics analyzed were compressive
strength at 7, 28 and 91 days, the elasticity modulus at 91 days,
propagation velocity of ultrasound waves at 91 days, and chloride
ion penetration at 28 days, for all mixtures. This study also deter-
mined the cost based on market values of the concrete components.
2. Aims of research
The main aim of this study is to make technical and economical
comparisons between the methods of dosage for SCC proposed
by Nan Su et al. in 2001 [1], Repette-Melo in 2005 [2], and Tutikian
& Dal Molin in 2007 [3], through the use of materials available in
the state of Rio Grande do Sul (RS), Brazil.
3. Materials and experimental program
In view of the objectives laid out here, an experimental program was
created and developed which defines the tests conducted on the dif-
ferent concretes as well as the materials used in the research. The
experimental work was carried out at the Construction Materials Lab
(CML) at the Vale do Rio dos Sinos University (UNISINOS).
A vertical axis mixer was used in the manufacturing of all concretes,
and the placing of materials followed an established order. Firstly, the
coarse aggregate was placed, followed by 80% of the water, regular
sand, fine sand, cement, admixture and the remainder of the water.
In total, 8 mixtures of concrete were measured, with 11 samples mea-
suring 10 cm in diameter and 20 cm in height being manufactured for
each one of those mixtures, totaling 88 samples. These samples re-
mained at room temperature for 24 hours, the tops of which protected
by sheets of glass. Next, they were removed from their molds and
taken to a moist chamber, where they were kept until they reached the
relevant ages at which the tests should be performed.
3.1 Showcase of the methods of dosage used
3.1.1 Nan Su et al Method [1]
This method is divided into steps, as shown in Fig. 1. To deter-
mine the amount of aggregates, the volume ratio between the fine
501
IBRACON Structures and Materials Journal • 2012 • vol. 5 • nº 4
B. F. TUTIKIAN | M. PACHECO
Figure 1 – Flowchart of the Nan Su
et al., [1] method