Gabion,Geo Textile & Renomatress

SPECIFICATION FOR GABIONS, GEO TEXTILE AND RENO MATRESS Gabions Description This work shall consist of the construction of protection walls and mattresses to embankment slopes, canal banks and canal beds, using rock filled wire mesh baskets known as gabions. Materials Materials used shall meet the requirements of the following unless otherwise specified. a). Gabions shall be PVC coated galvanised steel wire woven into a not more than 82x122 mm HEXAGONAL mesh and strength should be not less than 47 KN/m or equivalent. Gabions longer than 1.5 m shall have partition panels at 1.0 m centers. b).Broken rock for filling baskets shall be of sizes varying from about 100 mm in minimum dimension to 200 mm in maximum dimension and they shall be hard and durable, free from weathered pieces and extraneous matter. The rock shall be reasonably well graded between the two limiting sizes. Construction Requirements The canal banks against which gabions are to be placed shall be suitable trimmed and the ground shall be levelled and compacted as required by the Engineer. The baskets for the gabions shall be constructed to regular box shapes with rectangular sides of dimensions as shown on the drawings and assembled and erected strictly in accordance with the manufacturer’s instructions. The baskets shall be constructed out of 2.7 mm or more dia. wire to BS 1052/1980 having a tensile strength not less than 380 N/mm2 and not exceeding 500 N/mm2 or equivalent and shall be heavily (at least 275 gm/sq.m) hot dip galvanised to B.S. 443 /1982 or equivalent. The wire shall be coated with 0.5 mm thick uv stabilized PVC which shall be extruded onto the wire to limit air moisture, contaminants, and the lime coming in contract with the steel in the event the PVC is penetrated by damage. After coating the wire shall be woven with one and a half twists and edges shall be reinforced with heavier coated wire not less than 3.4 mm dia. core diameter, 4.4 mm overall diameter (Selvedge wire). Assembly shall be securely tied with PVC coated tie wire 2.2/3.2 mm 5% of Gabion weight of the same specification as the mesh wire. All tolerances limits to be as per specified in BS 1052/1980. The product should be ISO 9002 certified or equivalent. The tender should submit a certificate from a recognized independent testing authority confirming the offered gabions possesses the above values. The report should separately show the values of each and every detail stated above. The filling of baskets shall be carried out in-situ, unless otherwise directed. This requires that the empty baskets, open at the top, be positioned on the base or on top of the gabions and in filled with the rock pieces in such a manner as to completely fill up the baskets leaving only the minimum of voids prior to closing and securely tying the lid using wire of approved gauge. In building the walls the gabions shall be placed with scattered joints and they shall be tied together using strands of wire. In the event of this not being as the manufacturer’s requirements, the manufacturer’s requirements shall apply. The space just behind the gabion walls shall be protected by a geotextile filter in accordance with given below. All work to be done in accordance with the drawings and directions of the Engineer.

Backfill behind Gabions

After placing the geotextile filter, the backfilling behind gabions shall be carried out with approved sandy-gravel material in accordance with sub-Section 3.5. Measurement and Payment (a)

Measurement i) ii) iii) iv) V)

(b)

The gabion walls shall be measured in cubic metres, completed and accepted. The backfill material shall be measured. As per Section 3.5.2 Geotextile filter material shall be measured in square metres of material laid in place and accepted. The stone packing below foundation of gabion shall be measured in cubic metres as placed in position. Any excavation required, not included in canal excavation shall be measured in cubic metres.

Payment The quantities determined for gabion walls, geotextile filter material, and backfill material as provided above , shall be paid separately for at the contract unit rates in the Bill of Quantities and shall be full compensation for all labour, materials, tools and incidentals necessary for completion of the work including cutting and shaping the slopes and beds on which the walls are built. Any excavation required and rubble packing for the base shall be paid separately at the Contract unit rate for the items as per the bill of quantities.

Geotextile Filter Material (a)

General The level of the water table under construction such as roads, retaining walls, embankment etc. has to be limited to protect their stability. Drainage water will filter through the geotextile filter in to the gabion box and finally escape in to the canal.

(b)

Materials (i). The geotextile filter cloth shall be of approved filter fabric composed of polyester, polypropylene, polyethylene, polyamide non woven type or a combination of the above.

The Geotextile should be resistant to ultraviolet degradation and to biological and chemical environment normally found in soil. Further the offer Geotextile should conform to the property values listed below. Property

g/m2

Typical Roll Values 280

mm

2.5

Mechanical Grab Tensile Strength

N

1090

(Elongation @ Break) Wide Width Tensile Strength

% KN/m

60 17.5

Physical Mass per Unit Area

Test Method ASTM D526I ISO 9864 AS 3706-1 ASTM D5 199 AS 3706-1

Unit

BS6906-1 (Elongation @ Break) Trapezoidal Tear Mullen Burst Puncture Strength CBR Burst

Cone Drop Hydraulic Pore Size (O95) Permeability Permittivity Water flow rate

ASTM D4533 AS 3706-3 ASTM D3786 AS2001.2.4. method B ASTM D4833 GRI-GSI BS 6906-4 AS 3706-4 DIN 54307 BS 6906-6 AS 3706-5 ASTM D4751 (Dry) ASTM D4491 BS 9606-3 ASTM D4491 ASTM D4491 BS 9606-3

% N

50 445

Kpa

3030

N N

620 3780

mm

16 2450

mm cm/s S-1 1/min/m

0.150 0.48 0.41 1.8 4885 9370

2

Endurance UV Resistance (%retained & 500 hours)

ASTM D4355

%

70

The product should be ISO 9002 certified or equivalent. The tenderer should submit a certificate from a recognized independent testing authority confirming the offered Geotextile possesses the above stated values. The report should separately show the values of each and every detail stated above.

Reno Mattress The Reno mattress is a gabion where the depth is small in proportion to its length and width. It is divided in to several cells by transverse diaphragms and is fabricated from woven hexagonal steel wire netting. The netting used shall have the same specifications as for the gabions. The base, sides and ends are formed from one single panel of netting on which the diaphragms are fixed at 1 m centres. Lid is supplied as a separate panel of mesh. Typical unit would be 6 m X 2 m X 300 mm divided in to 6 cells. After joining together of the units the Reno mattress is filled up with stones which are hard, durable and 100-300 min in size of specific gravity not less than 2.0. The sequence of operations in the assembly and fitting of the Reno mattress is summarised as follows: (a) (b) (c) (d) (e)

assembly of mattress unit place geotextile filter behind the mattress placing in position and lacing together of units filling with stone and fitting the lids filling of the boxes shall be done as described in sub section 9.5.3.

Measurement and Payment (a)

Measurement (i) (ii)

(b)

The geotextile filter material for placing Reno mattress shall be measured in square metres of material. The Reno mattress of thickness 300 mm shall be measured on the area of the mattress laid in square metres.

Payment Payments for above items will be based on the contract unit rate for the items and shall include full compensation for all materials, labour, tools, equipment and preparation of surface for placing Reno mattress and any other incidentals necessary to complete the work to the specifications.