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

519. BITUMINOUS COLD MIX (INCLUDINGGRAVEL EMULSION) 1
519.1. The Design Mix
(i)Bituminous Cold Mix consists of a mixture of unheated mineral aggregate and emulsified or
cutback bitumen.
(ii)This Specification deals only with plant mix (as opposed to mixed- in-place).
(iii)Two types of mix are considered, namely Designed Cold Mix and Recipe Cold Mix. (iv)The
Design Mix procedure shall be used unless the Recipe Mix procedure is specifically approved by
the Engineer in charge.
519.2. Designed Cold Mix
(i)This Specification is based on The Asphalt Institute Manual MS-14, which contains additional
information for guidance.
(ii)These mixes are considered suitable for use as base course, appropriate to their stability, in
new work or major repair work.
519.2.1. Materials
519.2.1.1. Binder: (i)The binder shall be a bituminous emulsion as specified in AASHTO M 140
(ASTM D977)* or AASHTO M 208 (ASTM D2397)*, namely MS-2, MS-2h, HFMS-2, HFMS-2h,
HFMS-2s, SS-1, SS-lh, CMS-2, CMS-2h, CSS-1 and CSS-In.
(ii)Alternatively, a cutback bitumen as specified in AASHTO M 82 (ASTM D2027) or ASTM D
2026, namely MC 70, 250, 800 & 3000 and SC 250, 800 and 3000 may be used, or, if approved
by the Engineer in charge, an equivalent material which conforms with 1S:8887 and 18:217.
(iii)A general guide for the use of these binders is given in Table 500-35 and in the Manual for
Construction and Supervision of Bituminous Works. However the final selection shall be made
only after laboratory evaluation
TABLE 500-35.
USES OK BITUMEN IN COLD MIX
Type of Construction
Emulsified Bitumen
Anionic
Cationic
Cutback Bitumen
Medium
Curing
(MC)
Slow
Curing
(SC)
Cold-Laid Plant Mix
Pavement Base and
Surfaces
Open-Graded Aggregate
Well-Graded Aggregate
Patching, Immediate Use Patching
Stockpile
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
with the aggregates to be used.
(iv)The binder with the highest residual viscosity at ambient temperatures that can reasonably be
handled by the mixing and laying equipment proposed shall be used.
519.2.1.2. Aggregates:
(i)The aggregates shall comply with the requirements of Clause 504.2.2. and 504.2.3.
(ii)If the aggregates are not properly coated with anionic emulsion or cutback bitumen, a small
amount of hydrated lime, approved antis tripping agent (see Appendix 5) or a change to cationic
emulsion shall be proposed by the Contractor, for the approval of the Engineer in charge.