Specification Part 3 - Road & Bridge Works - Urban Administration ...

601. DRY LEAN CEMENT CONCRETE SUB-BASE
601.1. Scope
601.1.1. The work shall consist of construction of dry lean concrete sub base for cement concrete
pavement in accordance with the requirements of these Specifications and in conformity with the
lines, grades and cross-sections shown on the drawings or as directed by the Engineer, The work
shall include furnishing of all plant and equipment, materials and labour and performing all
operations, in connection with the work, as approved by the Engineer.
601.1.2. The design parameters of dry lean concrete sub-base, viz., width, thickness, grade of
concrete, details of joints, if any, etc. shall be as stipulated in the Contract drawings.
601.2. Materials
601.2.1. Source of Materials: The Contractor shall indicate to the Engineer the source of all
materials with relevant test data to be used in the lean concrete work sufficiently in advance and
the approval of the Engineer for the same shall be obtained at least 45 days before the scheduled
commencement of the work. If the Contractor later proposes to obtain the materials from a
different source, he shall notify the Engineer for his approval at least 45 days before such
materials are to be used.
601.2.2. Cement: Any of the following types of cement may be used with prior approval of the
Engineer:
(i) Ordinary Portland cement IS: 269
(ii) Portland Slag cement IS: 445
(iij) Portland Poziolana cement IS: 1489
If the sub grade is found to consist of soluble sulphates in a concentration more than 0.5 per cent,
cement used shall be sulphate resistant and shall conform to IS: 6909, cement to be used may
preferably be obtained in bulk form. It shall be stored in accordance with stipulations contained in
Clause 1014 and shall be subjected to acceptance test prior to its immediate use.
601.2.3. Aggregates:
601.2.3.1. Aggregates for lean concrete shall be natural material complying with IS: 383. The
aggregates shall not be alkali reactive. The limits of deleterious materials shall not exceed the
requirements set out in IS: 383. In case the Engineer considers that the aggregates are not free
from din, the same may be washed and drained for at least 72 hours before batching, as directed
by the Engineer.
601.2.3.2. Coarse aggregate: Coarse aggregate shall consist of clean, hard, strong, dense, non
-porous and durable pieces of crushed stone or crushed gravel and shall be devoid of pieces of
disintegrated stone, soft, flaky, elongated, very angular or splintery pieces. The maximum size of
the coarse aggregate shall he 25 mm. The coarse aggregate shall comply with Clause 602.2.4.2.
601.2.3.3. Fine aggregate: The fine aggregate shall consist of clean, natural sand or crushed
stone sand or a combination of the two and shall conform to IS : 383. Fine aggregate shall be free
from soft particles, clay, shale, loam, cemented particles, mica, organic and other foreign matter.
The fine aggregate shall comply with Clause 602.2.4.3.
601.2.3.4. The coarse and fine aggregates may be obtained in either of the following manner:
(i) In separate nominal sizes of coarse and fine aggregates and mixed together intimately before
use.