UFC 3-260-02
30 June 2001
(3) Durability.
(a) Seasonal frost exposure. Cycles of freezing and thawing can damage cement-
stabilized materials so TM 5-822-14/AFJMAN 32-1019 has specific testing criteria and limits based on
ASTM D 560 that must be met if the cement-stabilized material is to be exposed to freezing and thawing.
Adequate curing time in the field must also be available prior to the onset of freezing. Additional
assistance on problems with cement-stabilized materials under seasonal frost exposure is available from
the Army Cold Regions Research and Engineering Laboratory, 72 Lyme Road, Hanover, NH 03755.
(b) Carbonation. As with lime, atmospheric carbon dioxide can react with portland cement
to form calcium carbonate which can adversely affect portland cement-stabilization reaction products.
Proper and prompt mixing, compaction, and curing procedures that minimize the exposure of the
stabilized soil to atmospheric carbon dioxide avoid the problem. Reported problems have been with
highly weathered materials in Africa that were poorly compacted and cured.
(c) Sulfate attack. Cement-stabilized materials are susceptible to sulfate attack if sulfates
are present in the soil or water in contact with the stabilized material or if sulfates are present in
materials that are being stabilized. The sulfate attack reactions are expansive and highly disruptive. If
the soils or aggregates being stabilized contain clay minerals, sulfate resistant cements (Type II and V)
will not prevent sulfate attack. If cement-stabilization is contemplated where sulfates are present, the
HQUSACE (CEMP-ET), appropriate Air Force MAJCOM pavements engineer, or Naval Facilities
Engineering Service Center should be consulted for up-to-date guidance on this issue.
(4) Suitable Soils. The most economical materials for cement stabilization will generally be
well-graded sandy gravels or gravelly sands with a spectrum of particle sizes. Fine materials, coarse
materials, or poorly-graded materials will often require uneconomically high cement contents to achieve
adequate stabilization. Sticky materials such as CH clays may be difficult or impossible to mix
adequately with the cement stabilizer. Organic soils and some acidic sands respond poorly to cement
stabilization.
l. Pozzolan and Slag Stabilization. ASTM C 618 classifies pozzolans as Type N (natural
pozzolans), Type C (high-lime-content fly ash, a byproduct of burning lignite or subbituminous coal), or
Type F (low-lime-content fly ash, a by product of burning bituminous or anthracite coal). These materials
are not normally cementitious by themselves, but when combined with calcium hydroxide (lime), they will
form cementitious, pozzolanic bonds. Granulated blast furnace slag is a by-product of iron production
which can be ground to produce a slag cement. ASTM C 989 provides requirements and grade
classifications for this material. Neither material has been used extensively as a stabilizer by the
military, but their use is expanding in the construction industry. TM 5-822-14/AFJMAN 32-1019 provides
guidance on fly ash (the most commonly available pozzolan) stabilization. Slag is not addressed in the
manual, and HQUSACE (CEMP-ET), appropriate Air Force MAJCOM pavements engineer, or Naval
Facilities Engineering Service Center should be consulted for current guidance on use of this material in
military construction.
(1) Mechanisms. Pozzolans and ground granulated blast furnace (GGBF) slag react with
hydroxides to form cementitious bonds. Lime or occasionally portland cement are mixed with these
materials to provide the hydroxide activator. Some Class C fly ashes contain sufficient free lime (calcium
hydroxide) to be self-cementing, but the military has no experience at present using these materials as a
stabilizer without the addition of lime or portland cement. Properly cured lime-fly ash mixes often have
compressive strengths of 3.45 to 6.89 MPa (500 to 1,000 psi) with appreciably higher long-term
9-6
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