Page 25 - Riem-Vol6_nº2

196 IBRACON Structures and Materials Journal • 2013 • vol. 6 • nº 2
Ready mixed concrete: variability analysis of the compressive strength and physical properties along
the unloading of the truck mixer
Due the proposed of research, which aims to analyze mixtures of
ready-mix-concrete made in a mixer truck, the collection of sam-
ples was made outside the laboratory environment, with vehicles in
normal service, so we did not have control over weather aspects,
such as temperature and relative humidity, and about mixing time
and speed of the mixer.
The concrete used in research was specified with resistance to 35MPa
to 28 days, slump test of 120±20mm and coarse aggregate with Dmax:
9.5mm. The concrete recipe provided by concrete batch plant on in-
voice to 8m³ was: CPV-ARI RS - 2600kg, POZZOLAN - 468kg, FINE
SAND - 1472kg, MEDIUM SAND - 4552kg, COARSE AGGREGATE 0
- 8648kg, WATER - 1520l, ADDITIVE - 26kg. In unit proportion in order
cement, sand, gravel and w / c ratio, the recipe is: 1:1.964:2.819:0.495.
the compressive strength and physical properties. The topic of this
research contributes to studies on quality control of concrete and
shows the necessity for complementation in current normalization,
in order to improve confidence about the quality and safety of con-
crete structures.
2. Materials and experimental program
To analyze the uniformity of ready-mix-concrete was defined the vari-
ables of response to the research as the compressive strength, slump
test and coarse aggregate content. Was defined as controllable vari-
able, five sampling points along the discharge from the concrete mixer
truck, and was used conventional concrete to the research.
Table 1 – Data of slump test, compressive strength and coarse aggregate content