05.chapter iii

Hanoi – Hochiminh city railway line Do Vang Bridge’s construction bridges safety improvement project technology of beam casted on scaffolding

CHAPTER III: MATERIAL REGULATIONS

I. GENERAL

All meterials for box girder and other items shall be in accordance with the

Specification of Project and shall be taken test sample according to quality controlling

plan. Sample for test and construction shall be supervised and approved by Engineer.

Just only use materials which are approved by Engineer according to Specification

and Quality Controlling Plan.

Materials which not satisfy the above requirement shall be rejected and removed out

from Site.

Approved material source shall be use for the entire Project. For a new source, it is

necessary to take sample and be approved by Engineer in accordance with Specification

if the source has any change.

During placing concrete for continuously voided slab beam segments, all materials

must be enough for mixing and providing not interupted.

II. MATERIALS

1. Reinforcement

a. High strength reinforcement

High strength strand with low relaxation shall be in accordance with ASTM416-99

standard of Grade 270 or equivalent, with the main parameters as follows:

+ Grade 270, low relaxation.

+ Breaking strength: fpu = 1860MPa

+ Yield limit: fpy = 1674 MPa

+ Modulus of elasticity: 195000 MPa

+ Relaxation after 1000h at 20C ≤ 2,5 %.

Construction regulations:

+ High strength strand shall be not welded.

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+ Each coil of cable must have Certificate of Producer. The Certificate shows

relative curve between load and elongation, measured area, elastic mudulus for each

lot.

+ High strength cable lots shall be checked before testing, taken sample to test for

each lot or taken a group sample for every 20T.

+ In any case, jacking force for each strand is not over 0, 80 of minimum ultimate

strength of cable.

+ Jack must be suitable with presstressed tendon about structure and tensioning

force. Jack and gauge shall be checked before using.

b. Non-prestressed reinforcement

The Subcontractor intends to use Viet Y Steel for construction Project.

Non-prestressed reinforcement must be in accordance with Specification of Project:

JISG 3112

SD345

2. Prestressed anchor

Pre-stressed anchor must be conformed to 22TCN 267-2000 Standard and the

following requirements:

+ All anchor devices must have enough capacity to keep prestressed cable with a

stress not less than 95% of ultimate tensile strength of prestressed cable showed on

Certificate of Producer and anchor, cable Test Result.

+ Anchor shall be checked to ensure type as submitted, geometric dimension,

mechanical defect to reject defected anchor.

3. Duct

The corrugated duct must be appropriate, synchronous with type, grade of prestressed

cable and anchor. Duct system shall be airproof, waterproof. Diameter of duct must be

greater at least 6mm than nominal diameter of tendon; cross section area must be greater

2.5 times than tendon area.

The minimum thickness of duct must be in accordance with approved design and

instruction of producer that be agreed by Engineer.

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4. Concrete

The girder concrete is B arccording to Specification of Project.

Mix design shall conform to Specifications of Project.

Material regulation is as follows:

a. Cement

Cement is Portland cement corresponding to JIS R5210 or ASTM-C150-98 (TCVN

PCB40, TCVN6260-1997) standard. Expiry date and Manufacturer Certificate shall be

submitted before using. Product lots brought into Site must have full bags, components.

Bagged cement shall be kept in a temporary depot and used on time since the material

has been delivered.

Bulk cement shall be kept in silo corresponding to manufacturer regulations.

b. Fine aggregate: Sand

Fine aggregate using for concrete shall be in accordance with JISA 1102 or equivalent

standard.

Aggregate shall be kept to avoid segregating or contaminating. The centre of depot

must be prevented from moisture excess.

To prevent different-size aggregates from mixing together, make a baffle between

them.

Only use uncontaminated, non-toxic mud, clean fine aggregate. The fineness modulus

must satisfy the Specification of Project as the following:

+ Granular composition (according to JISA 1102 standard):

Sieve number (mm) Percentage passing by weight

10 100

5 90~100

2.5 80~100

1.2 50~90

0.60 25~65

0.30 10~35

0.15 2~10A

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The Subcontractor has intention in using Mia Duong, Ha 12 – Bo Trach – Quang

Binh coarse sand for concreting works of Project.

Aggregate shall be checked with the above requirements before constructing.

c. Coarse aggregate: Rock 1x2

Coarse aggregate must respond to JISA 1102 or equivalent.

The Subcontractor intends to use stones Len Cut Tai - Quang Trach - Quang Binh for

concreting works of Project.

Coarse aggregate size is shown in the below table:

Sieve number (mm) Percentage passing by weight

30 100

25 95~100

20 -

15 30~70

10 -

5 0~10

2.5 0~5

d. Water

Water for mixing or curing concrete must be fresh water, uncontaminated with oil,

saline, acid, sugar, vegetable or other toxic materials. Excluding water approved as

potable water by competent authority, others shall be tested and satisfied AASHTO-T26

standard: Water for concrete and mortar. Water/concrete ratio is not over 0.40.

Water sources for constructing continuous box girder casted on scaffolding of Do

Vang Bridge shall be the source using for Sub-structure items of Project.

Check pH value at site before placing concrete or test water sample again if

necessary.

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e. Admixture

Admixture shall meet instructions JISA 6204.

Admixture that boots setting speed, increases mobility or retarding admixture, wetting

admixture, v.v… can be use but must be approved by Engineer before constructing.

Admixture may be one of the following types: SiKa Viscocrete 3000-10 to be in

accordance with real construction requirements at Site.

Admixture not the type as required shall be rejected and removed out of Site. Water

fixed content and admixture shall be put together at mixing plant.

Inspector shall check type, maintenance, and ratio of concrete admixture whether as

required or not.

5. Pumped grout

Grout made from Pooclang cement, water and admixture are accepted by Engineer.

Grout is mixed as follows:

Bleeding rate is not over 3%

Non-shrinkage

Swelling index is not over 10%. But this rate is always smaller than bledding rate after

atomizing up to bleed completely.

Compressive strength of cylinder (50x100mm) of 28 days is not smaller than 20 MPa.

The rate of water/cement is not over than 0.4

The content of Cl is not over 0.3kg/m3

Ecflux time is from 10-15 seconds according to Marsh Cone testing.

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05.chapter iii

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