ready mixed concrete (sni)

ASSALAMUALAIKUM, SELAMAT PAGI, SALAM SEJAHTERA BUAT KITA

SEMUA

Beton Siap Pakai(Ready-Mixed Concrete)

SNI 03-4433-1997/ ASTM C.94

Oleh:A. SUBAGDJA, MT

Maksud, Tujuan, Ruang Lingkup dan Pengertian

• Maksud: Spesifikasi Beton Siap Pakai dimaksudkan sebagai acuan dan pegangan dalam produksi dan penyerahan beton siap pakai dalam bentuk beton segar dari produsen kepada konsumen.

• Tujuan: Spesifikasi ini ialah untuk memberikan persyaratan kualitas beton siap pakai yang diproduksi.

• Ruang Lingkup: Spesifikasi ini memuat persyaratan dan ketentuan teknis beton siap pakai dalam bentuk beton segar.

• Pengertian: Beton siap pakai adalah beton yang dicampur dalam suatu mesin pengaduk staioner atau dalam truk pengaduk, dan diserahkan kepada konsumen beton dalam keadaan segar

Persyaratan Bahan• Semen: untuk campuran beton dapat memakai jenis-jenis semen

Portland yang memenuhi SII 0013 tentang Mutu dan Cara Uji Semen Portland, bila digunakan Semen Portland Pozolan harus memenuhi SNI 0129-1987-A tentang Kualitas dan Cara Uji Semen Portland Pozolan.

• Agregat: harus memenuhi SII 0052-80 tentang Agregat Beton, Mutu dan Cara Uji dan SNI 03-6861.1-2002 tentang Spesifikasi Bahan Bangunan Bagian A.

• Air: harus memenuhi SNI 03-6861-.1-2002 tentang Spesifikasi Bahan Bangunan Bagian A.

• Bahan Tambah: Jenis bahan tambahan dan penggunaannya harus memenuhi SNI 03-2495-1991 tentang Spesifikasi Bahan Tambahan untuk Beton, SNI 03-2460-1991 tentang Spesifikasi Abu Terbang sebagai Bahan Tambahan untuk Campuran Beton, dan SNI 03-2496-1991 tentang Spesifikasi Bahan Tambahan Gelembung Udara untuk Beton.

Informasi Yang perlu Diberikan Konsumen Kepada Produsen

Dalam pemesanan beton siap pakai, konsumen minimal harus memberikan informasi. Jenis dan kualitas beton yang dipesan serta persyaratannya diperinci dalam suatu formulir yang memuat penjelasan sebagai berikut :1) Campuran beton khusus untuk campuran beton yang ditentukan;2) Jenis semen;3) Jenis agregat normal, ringan atau berat;4) Maksimum besar butir agregat;5) Untuk campuran yang direncanakan, kualitas beton ditentukan

dengan kuat tekan beton yang disyaratkan;6) Untuk campuran yang ditentukan, harus diberikan susunan

perbandingan campuran dari bahan-bahan beton dalam satuan kilogram;

7) Kadar semen minimum, dinyatakan dalam kilogram per meter kubik beton segar yang dipadatkan.

Peralatan ProduksiPeralatan untuk produksi beton siap pakai harus memenuhi ketentuan sebagai berikut :1) Peralatan untuk menakar harus mempunyai ketelitian ± 3 %

terhadap berat semen, air atau seluruh agregat yang sedang ditakar dan ketelitian ± 5 % untuk bahan tambahan yang sedang ditakar;

2) Semua alat penakar harus dirawat baik agar selalu bersih dan siap pakai;

3) Semua alat penakar harus ditepatkan titik nolnya setiap ahri dan harus dikalibrasi setiap enam bulan;

4) Mesin pengaduk harus memenuhi persyaratan standar yang berlaku atau standar lain yang disepakati bersama.

Batching, Mixing, Transporting, and

Handling Concrete

Batching, Mixing, Transporting, and Handling Concrete

Ordering Ready Mixed Concrete

Specify:n Coarse aggregate sizen Slumpn Air contentn Basis for proportioning,

select Options A ,B, or C.

ASTM C 94

Batching, Mixing, Transporting, and Handling Concrete

Ordering Ready Mixed Concrete

Option A—performance based:

Purchaser specifies:n Compressive strength

Concrete producer selects mix proportions.

ASTM C 94

Batching, Mixing, Transporting, and Handling Concrete

Ordering Ready Mixed Concrete

Option B—prescription based:

Purchaser specifies mixture proportions including:

n Cement contentn Water contentn Admixture type and content

ASTM C 94

Batching, Mixing, Transporting, and Handling Concrete

Ordering Ready Mixed Concrete

Option C—mixed option:

Purchaser specifies:n Compressive strengthn Cement contentn Admixture type and content

Concrete producer selects mix proportions.

ASTM C 94

Batching, Mixing, Transporting, and Handling Concrete

Batching

Batching, Mixing, Transporting, and Handling Concrete

Stationary Mixing

n Stationary Mixersu Onsite or Central Mix R/M plantu Used for complete or shrink

mixingn Mixer Types ― up to 9m3

u Tilting or non-tilting drumu Open top revolving blade or

paddlen Typical complete mixing times

u Minimum of 1 min. for up to 1 yd3 or less mixer capacity plus 15 sec. for each additional yd3 or fraction thereof

Batching, Mixing, Transporting, and Handling Concrete

Ready Mixed Concrete

n Shrink-mixed concreteu mixed partially in a

stationary mixer and completed in a truck mixer

n Truck-mixed concrete u mixed completely in a

truck mixer

Batching, Mixing, Transporting, and Handling Concrete

Ready Mixed Concrete

n Central-mixed concrete u mixed completely in a

stationary mixer u delivered in

H a truck agitatorH a truck mixer operating

at agitating speed H a nonagitating truck

Batching, Mixing, Transporting, and Handling Concrete

Ready Mix Plant

Batching, Mixing, Transporting, and Handling Concrete

Truck Mixed Concrete

n 70 to 100 revolutions required for mixing,

mixing speed = 6 to 18 rpm

n After mixing, drum revolves at agitating speed, 2 to 6 rpm

n Discharge before exceeding 300 drum revolutions

n Discharge before 1½ hours

ASTM C 94

Batching, Mixing, Transporting, and Handling Concrete

Mobile Batcher Mixer

n Used for: Intermittent production of concrete at jobsite, or small quantities.

n Advantages: Combined materials transporter and batching and mixing system. One-man operation.

n Watch for: Good preventive maintenance program. Materials must be identical to those in original mix design.

Batching, Mixing, Transporting, and Handling Concrete

Nonagitating Truck

n Used for: Transport concrete on short hauls over smooth roadways.

n Advantages: Cost of nonagitating equipment is lower than that of truck agitators or mixers.

n Watch for: Slump should be limited. Possibility of segregation. Height upon discharge is needed.

Batching, Mixing, Transporting, and Handling Concrete

Agitator Trucks

n Used for: Transporting concrete for all uses. Haul distances must allow discharge of concrete within 1½ hours.

n Advantages: Operate usually from central mixing plants.

n Watch for: Timing of deliveries should suit job organization. Concrete crew and equipment must be ready onsite to handle concrete.

Batching, Mixing, Transporting, and Handling Concrete

Remixing Concrete (1)

Water may be added at jobsite provided:

n Spec. w/c-ratio is not exceededn Measured slump less than specifiedn Allowable mixing and agitating time

(or drum revolutions) are not exceeded

n Concrete is remixedu min. 30 rev. at mixing speedu until uniformity is within limits

ASTM C 94 (AASHTO M 157)

Batching, Mixing, Transporting, and Handling Concrete

Transporting and Handling

n Used for: Short flat hauls on all types of onsite concrete construction.

n Advantages: Versatile—ideal inside and on jobsites with changing placing conditions.

n Watch for: Slow and labor intensive.

Wheelbarrows and Buggies

Batching, Mixing, Transporting, and Handling Concrete

Belt conveyor

n Used for: Conveying concrete horizontally or higher/lower level.

n Advantages: Adjustable reach, traveling diverter, variable speed.

n Watch for: End-discharge arrangements needed to prevent segregation and mortar on return belt. Belt cover needed in hot and windy weather.

Transporting and Handling

Batching, Mixing, Transporting, and Handling Concrete

Truck mounted conveyors

n Used for: Conveying concrete horizontally or higher/lower level.

n Advantages: Conveyer arrives with concrete. Adjustable reach and variable speed.

n Watch for: End-discharge arrangements needed to prevent segregation and mortar on return belt. Belt cover needed in hot and windy weather.

Transporting and Handling

Batching, Mixing, Transporting, and Handling Concrete

Buckets

n Used with: Cranes, cableways, and helicopters.

n Advantages: Enables full versatility of cranes, cableways, and helicopters to be exploited. Clean discharge.

n Watch for: Select bucket capacity to conform to size of the concrete batch and capacity of placing equipment.

Transporting and Handling

Batching, Mixing, Transporting, and Handling ConcreteRear Discharge Front

Discharge

Transporting and Handling

Batching, Mixing, Transporting, and Handling Concrete

Cranes and Bucketsn Used for: Work above ground

level.n Advantages: Can handle

concrete, reinforcing steel, formwork, and sundry items.

n Watch for: Has only one hook. Careful scheduling between trades and operations is needed to keep crane busy

Transporting and Handling

Batching, Mixing, Transporting, and Handling Concrete

Pumps

n Used for: Conveying concrete from central discharge point to formwork.

n Advantages: Pipelines take up little space and can be readily extended. Delivers concrete in continuous stream. Pump can move.

n Watch for: Constant supply of freshly-mixed concrete is needed without any tendency to segregate.

Transporting and Handling

Batching, Mixing, Transporting, and Handling Concrete

Flexible Hose at End of Pump’s Rigid Pipeline

Transporting and Handling

Batching, Mixing, Transporting, and Handling Concrete

Screw Spreaders

n Used for: Spreading concrete over large flat areas.

n Advantages: Concrete can be quickly spread over a wide area to a uniform depth.

n Watch for: They are normally used as part of a paving train. They should be used for spreading before vibration is applied.

Transporting and Handling

Batching, Mixing, Transporting, and Handling Concrete

Work Above Ground Level

Transporting and Handling

Batching, Mixing, Transporting, and Handling Concrete

Videos 1/3

Stationary MixersBatching

Batching, Mixing, Transporting, and Handling Concrete

Videos 2/3

Nonagitating MixersTruck Mixer Types

Batching, Mixing, Transporting, and Handling Concrete

Videos 3/3

Agitators

Interpreting the specification

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