Kajian telah dijalankan untuk mengenalpasti kandungan optimum gentian keluli yang
perlu digunakan untuk mencapai keupayaan lenturan rasuk maksimum konkrit
berprestasi tinggi. Gentian keluli hujung bercangkuk yang mempunyai garispusat 0.75
mm dan panjang 60 mm telah digunakan. Kandungan gentian keluli sebanyak 0%, 1%,
2% dan 3% telah digunakan dalam campuran konkrit. Kekuatan mampatan konkrit yang
melebihi 70 MPa telah direka bentuk, kerana projek ini berfokus kepada konkrit
berprestasi tinggi. Sejumlah empat ujian telah dijalankan berdasarkan kepada BS1881.
Empat ujian tersebut adalan ujian meja aliran, ujian mampatan kiub, ujian ketegangan
pisah dan ujian lenturan rasuk. Daripada ujian meja aliran apabila kandungan gentian
keluli ditambah, aliran konkrit semakin berkurangan. Aliran konkrit untuk 0%, 1%, 2%
and 3% gentian keluli adalah 654 mm, 605 mm, 584 mm dan 556 mm. Semakin
bertambah kandungan keluli gentian, semakin itu dos superplastik perlu ditingkatkan
untuk mengekalkan aliran konkrit yang sama. Melalui ujian mampatan, didapati bahawa
tambahan gentian keluli meningkatkan kekuatan mampatan. Optimum gentian keluli
sebanyak 2% dapat mencapai kekuatan mampatan sebanyak 105.7 MPa (14.9%
peningkatan dalam kekuatan mampatan dari sampel kawalan). Selain itu, kekuatan
tegangan juga meningkat dengan tambahan gentian keluli. Optimum gentian keluli
sebanyak 2% dapat mencapai kekuatan tegangan 9.1% MPa (46.8% peningkatan dalam
kekuatan tegangan dari sampel kawalan). Empat rasuk bersaiz 100 mm x 300 mm x 2000
mm telah direka untuk diuji dalam ujian lenturan rasuk. Kekuatan lenturan maksimum
21.65 MPa dicapai apabila 2% gentian keluli diguna. Peningkatan selanjut melebihi 2%
gentian keluli akan mengurangkan kekuatan konkrit berprestasi tinggi. Kekakuan konkrit
berprestasi tinggi dengan gentian keluli lebih tinggi dari sampel kawalan sebelum gagal.
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A study was done to identify the optimum fibre content to achieve maximum flexural
capacity of high performance concrete beam. Hook end steel fibre of diameter 0.75 mm
and 60 mm length have been used. The proportion of steel fibre that have been used are
0%, 1%, 2% and 3% by mass, this is done by adding to concrete mixture. The targeted
compressive strength of concrete is more than 70 MPa since it is high performance
concrete. A total of four tests were conducted according to BS1881. The four tests
conducted are flow table test, cube compression test, tensile splitting test and flexural
test. From the flow test, as the steel fibre content increases the flow started to decrease.
The flow result for 0%, 1%, 2% and 3% steel fibre are 654 mm, 605 mm, 584 mm and
556 mm respectively. The superplasticizer dose should be increased as steel fibre content
increase to maintain the same flow. From the compressive test, the addition of steel fibre
increases the compressive strength of high performance concrete. The optimum steel
fibre of 2% able to achieve maximum compressive strength of 105.7 MPa (14.9% gain
in compressive strength than control sample). Other than that, addition of steel fibre also
improve the tensile strength of concrete. The optimum steel fibre of 2% able to achieve
maximum tensile strength of 9.1 MPa (46.8% gain in tensile splitting strength than
control sample). Four beams of 100 mm x 300 mm x 2000 mm size were casted for the
four-point flexural test. The highest flexural strength that was obtained is 21.65 MPa
which was achieved at 2% of steel fibre. Further increase of steel fibre more than 2%
reduced the respective strength of high performance concrete. The stiffness of high
performance concrete with steel fibre is high compared to control sample before failure.
Assessment of hook end steel fibre as a substitute material in high performance concrete beam / Jegathisan Manoharan