INFLUENCE OF USING NON-STANDARD SPECIMEN ON COMPRESSIVE STRENGTH OF NORMAL AND HIGH STRENGTH CONCRETE EXPERIMENTAL AND SIMULATION
Abstract: Compressive strength
of concrete is one of the most important test for construction properties for
quality control of concrete and design new constructions, there are different
molds that are used for casting concrete specimen during the concrete works
according to various standards at different countries. On the other hand, it is
known that different shapes and sizes of concrete specimen can cause
differences in the results of compressive strength.In this research the
influence of specimen sizes and shapes on compressive strength of normal and
high strength concrete are investigated using experimental and simulation
study.
The experimental study was conducted for six different specimen types
cube 150 mm, cube 100 mm, cube 75 mm, cylinder Ø150×300 mm, Ø100×200 mm,
Ø75×150 mm. At six different concrete strength level was 20,30,40,50,60 and 70
MPa according to standard cube specimen and tested at 28 Days of age. For The
experimental study, hardened density, non-destructive tests (Rebound hammer and
UPV), compressive strength and splitting tensile strength for different
concrete strength level were performed and some analyses were done to obtain
conversion factors and some relations between these tests.
The simulation study was conducted by using ANSYS software for two
different specimen size cube 150 mm, cube 75 mm, At two different concrete
strength level was for normal compressive strength 20 MPa and for high
compressive strength 70 MPa. The analyses were done to know the influence of
size and shape on the compressive strength tests of normal and high strength
concrete.
The results of analyses indicate that for all testing, there is a bigger influence
of variation of size and shape of the specimens, by changing the compressive
strength level. The compressive strength increases as the specimen size
decreases.. Also The compressive strength of cube 150 mm is generally higher
than strength cylinder Ø150×300 mm and The conversion factors of compressive
strength between is varied from 0.76 to 0.88 for the designed cube compressive
strength of 20 to 70 MPa. The conversion factors of compressive strength
between standard and non-standard specimen at different concrete strength at 28
days to equivalent 150 mm standard cube specimen had been determined and
presented in table 4.7.
The correlation between (split tensile test / Schmidt hammer test/UPV
test) of standard specimen 150 x 150 mm cube to compressive strength of
non-standard specimen had been determined and presented in the tables 4.8 and
4.9.
The effect of size and shape on the compressive strength tests of normal
and high strength concrete had been analysis by using ANSYS software. This
affected decrease as compressive strength increase.
Keywords: compressive strength
level, influence of specimen sizes and shapes, conversion factors, splitting
tensile strength, Schmidt hammer test, UPV
Author: ABDULATI MOHAMED
ESBATA
Journal Code: jptsipilgg140012
