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Sedikit latar belakang bagaimana besi beton dibuat

Besi beton diproduksi secara umum terdiri dari 3 jenis: besi beton permukaan polos (round bar), besi beton ulir (deformed bar) dan besi beton kanal u (shape). Bahan baku besi beton adalah billet, yang juga merupakan balok baja berukuran 100 x 100 mm, 110 x 110 mm, 120 x 120mm dengan panjang masing-masing sekitar 170 mm. Bahan baku dari billet sendiri adalah besi-besi tua, skrap, serta bahan penolong seperti kokas, grafit, lime, ferro alloys yang dilebur dengan berbagai metode. Bahan penolong tadi digunakan untuk mendapatkan unsur carbon (C), Si (silicon), Mn (Mangan) yang akan sangat berpengaruh pada qualitas besi beton.
 
Mutu besi beton yang baik adalah yang telah memiliki kekuatan tarik (standard yield strength / Ys) minimal 24 kg / mm2. Kadar carbon berpengaruh besar kepada sifat mekanik dari besi beton. Kadar carbon yang terlalu besar akan membuat besi beton menjadi lebih getas dan akan meningkatkan kekerasan dan kekuatan tarik tetapi keuletannya cenderung menurun. Kadar unsur silikon berpengaruh terhadap struktur mikro besi beton. Kadar silikon yang rendah mengakibatkan besi menjadi kropos. Kadar unsur mangan berpengaruh besar pada keuletan besi beton. Unsur mangan yang terlalu banyak dapat meningkatkan keuletan tetapi mengurangi kekerasan.

Cara menghitung berat besi beton SNI (Standard Nasional Indonesia)
 
Polos dengan grade U24 (Standard Yield Strength: 24 kg / mm2)

Ulir dengan grade U40 (Standard Yield Strength: 40 kg / mm2)

Berat (dalam kg) = diameter (mm) * diameter (mm) * panjang (m) * 0.006165

0.006165 merupakan coefisien dalam mencari berat besi beton.

Sebagai contoh besi dengan diameter 10mm dan panjang 12m mempunyai berat

10*10*12*0.006165 = 7.398 kg

Untuk daerah bali dan sekitarnya, besi yang banyak dipasarkan adalah besi dari PT Hanil Jaya Steel - Surabaya. Hal ini dikarenakan biaya transportasi yang lebih murah dan kualitas besi beton yang baik. Besi beton SNI dari pabrik Hanil mempunyai toleransi 0.2mm dengan panjang 12m. Besi beton jenis ini mempunyai marking seperti "HIJ SNI 16mm" untuk ukuran 16mm.

Besi Beton Ulir/Sirip SNI 13mm

Besi Beton Polos SNI 10mm

Contoh diatas adalah besi beton ulir SNI 13mm (S13 = Sirip 13) dan besi beton polos SNI 10mm (P10 = Polos 10)

Selain besi beton jenis SNI, terdapat juga besi beton NON-SNI atau sering kali disebut BANCI. Kekuatan tarikan atau yield strength dari besi beton jenis ini tidak dapat dipastikan. Untuk besi beton dengan marking HJ menurut informasi dari pabrik mempunyai kekuatan U19-20 untuk yang jenis polos dan untuk jenis ulir mempunya kekuatan U25-30. Toleransi untuk besi beton jenis ini biasanya lebih besar sampai 0.3mm dengan panjang 12m dan terdapat marking dengan berbagai tanda salah satunya HJ.

Besi Beton NON SNI Ulir/Sirip 13mm

Besi Beton NON SNI Ulir/Sirip 13mm (Ukuran Sket 12.5mm)
 
Terdapat lagi jenis besi beton tarikan. Besi beton jenis ini biasanya tidak mempunyai panjang 12m dan tidak terdapat marking atau tanda.
 
Perhatian!

Terdapat fenomena belakangan ini banyak penjual menjual kawat baja dan bukan besi beton. Besi beton dengan diameter ukuran 6-10mm yang sering kali menjadi korban. Fungsi dari kawat baja sangat berbeda dengan besi beton. Kawat baja berfungsi untuk pengikat dan besi beton berfungsi untuk penyangga. Sehingga kekuatan tarikan kawat baja jauh dibawah kekuatan besi beton. Hanya saja diameter kawat baja ini sama besar dengan besi beton ukuran tertentu. Hal ini sering kali digunakan untuk mendapatkan pasar atau pun mengeruk keuntungan maximal.
 
Anda dapat mempercayakan supplier besi anda kepada kami. Kami hanya menjual besi dari PT Hanil Jaya Steel - Surabaya dengan marking HIJ untuk besi beton SNI dan marking HJ untuk besi beton NON-SNI.

 

BELAKANG BAGAIMANA BESI BETON DIBUAT

Public perceptions of race relations in America have grown substantially more negative in the aftermath of the death of a young black man who was injured while in police custody in Baltimore and the subsequent unrest, far eclipsing the sentiment recorded in the wake of turmoil in Ferguson, Mo., last summer.

Americans are also increasingly likely to say that the police are more apt to use deadly force against a black person, the latest New York Times/CBS News poll finds.

The poll findings highlight the challenges for local leaders and police officials in trying to maintain order while sustaining faith in the criminal justice system in a racially polarized nation.

Sixty-one percent of Americans now say race relations in this country are generally bad. That figure is up sharply from 44 percent after the fatal police shooting of Michael Brown and the unrest that followed in Ferguson in August, and 43 percent in December. In a CBS News poll just two months ago, 38 percent said race relations were generally bad. Current views are by far the worst of Barack Obama’s presidency.

The negative sentiment is echoed by broad majorities of blacks and whites alike, a stark change from earlier this year, when 58 percent of blacks thought race relations were bad, but just 35 percent of whites agreed. In August, 48 percent of blacks and 41 percent of whites said they felt that way.

Looking ahead, 44 percent of Americans think race relations are worsening, up from 36 percent in December. Forty-one percent of blacks and 46 percent of whites think so. Pessimism among whites has increased 10 points since December.

Continue reading the main story
Do you think race relations in the United States are generally good or generally bad?
60
40
20
0
White
Black
May '14
May '15
Generally bad
Continue reading the main story
Do you think race relations in the United States are getting better, getting worse or staying about the same?
Getting worse
Staying the same
Getting better
Don't know/No answer
All adults
Whites
Blacks
44%
37
17
46
36
16
41
42
15

The poll finds that profound racial divisions in views of how the police use deadly force remain. Blacks are more than twice as likely to say police in most communities are more apt to use deadly force against a black person — 79 percent of blacks say so compared with 37 percent of whites. A slim majority of whites say race is not a factor in a police officer’s decision to use deadly force.

Overall, 44 percent of Americans say deadly force is more likely to be used against a black person, up from 37 percent in August and 40 percent in December.

Blacks also remain far more likely than whites to say they feel mostly anxious about the police in their community. Forty-two percent say so, while 51 percent feel mostly safe. Among whites, 8 in 10 feel mostly safe.

One proposal to address the matter — having on-duty police officers wear body cameras — receives overwhelming support. More than 9 in 10 whites and blacks alike favor it.

Continue reading the main story
How would you describe your feelings about the police in your community? Would you say they make you feel mostly safe or mostly anxious?
Mostly safe
Mostly anxious
Don't know/No answer
All adults
Whites
Blacks
75%
21
3
81
16
3
51
42
7
Continue reading the main story
In general, do you think the police in most communities are more likely to use deadly force against a black person, or more likely to use it against a white person, or don’t you think race affects police use of deadly force?
Police more likely to use deadly force against a black person
Police more likely to use deadly force against a white person
Race DOES NOT affect police use of deadly force
Don't know/No answer
All adults
Whites
Blacks
44%
37%
79%
2%
2%
1%
46%
53%
16%
9%
8%
4%
Continue reading the main story
Do you favor or oppose on-duty police officers wearing video cameras that would record events and actions as they occur?
Favor
Oppose
Don't know/No answer
All adults
Whites
Blacks
92%
93%
93%
6%
5%
5%
2%
2%
2%

Asked specifically about the situation in Baltimore, most Americans expressed at least some confidence that the investigation by local authorities would be conducted fairly. But while nearly two-thirds of whites think so, fewer than half of blacks agree. Still, more blacks are confident now than were in August regarding the investigation in Ferguson. On Friday, six members of the police force involved in the arrest of Mr. Gray were charged with serious offenses, including manslaughter. The poll was conducted Thursday through Sunday; results from before charges were announced are similar to those from after.

Reaction to the recent turmoil in Baltimore, however, is similar among blacks and whites. Most Americans, 61 percent, say the unrest after Mr. Gray’s death was not justified. That includes 64 percent of whites and 57 percent of blacks.

Continue reading the main story
As you may know, a Baltimore man, Freddie Gray, recently died after being in the custody of the Baltimore police. How much confidence do you have that the investigation by local authorities into this matter will be conducted fairly?
A lot
Some
Not much
None at all
Don't know/No answer
All adults
Whites
Blacks
29%
31
22
14
5
31
33
20
11
5
20
26
30
22
In general, do you think the unrest in Baltimore after the death of Freddie Gray was justified, or do you think the unrest was not justified?
Justified
Not justified
Don't know/No answer
All adults
Whites
Blacks
28%
61
11
26
64
11
37
57
6

Negative View of U.S. Race Relations Grows, Poll Finds

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