Civil Engineering Reference
In-Depth Information
mixed concrete plant or jobsite. Tests have shown that the
effect of hot cement on the workability and strength devel-
opment of concrete is not significant (
Lerch 1955
). The
temperatures of the mixing water and aggregates play a
much greater role in establishing the final temperature of
the concrete as mixed.
Fig. 2-53. A small amount of cement is shipped in bags,
primarily for mortar applications and for small projects.
(59411)
stacked against outside walls. Bags to be stored for long
periods should be covered with tarpaulins or other water-
proof covering. Bags should be stored so that the first in are
the first out.
On small jobs where a shed is not available, bags
should be placed on raised wooden platforms (pallets)
above the ground. Waterproof coverings should fit over the
pile and extend over the edges of the platform to prevent
rain from reaching the cement and the platform (Fig. 2-54).
Rain-soaked platforms can damage the bottom bags of
cement.
Cement stored for long periods may develop what is
called warehouse pack. This can usually be corrected by
rolling the bags on the floor. At the time of use, cement
should be free-flowing and free of lumps. If lumps do not
break up easily, the cement should be tested before it is
used in important work. Standard strength tests or loss-on-
ignition tests should be made whenever the quality of a
cement is doubtful.
Ordinarily, cement does not remain in storage long,
but it can be stored for long periods without deterioration.
Bulk cement should be stored in weathertight concrete or
steel bins or silos. Dry low-pressure aeration or vibration
should be used in bins or silos to keep the cement flowable
and avoid bridging. Due to fluffing of cement, silos may
hold only about 80% of rated capacity.
Fig. 2-54. When stored on the job, cement should be
protected from moisture. (36052)
REFERENCES
Abrams, Duff A., “Effect of Hydrated Lime and Other
Powdered Admixtures in Concrete,”
Proceedings of the
American Society for Testing Materials,
Vol. 20, Part 2, 1920.
Reprinted with revisions as Bulletin 8, Structural Materials
Research Laboratory, Lewis Institute, June 1925, 78 pages.
Available through PCA as
LS008
,
http://www.portcement.
org/pdf_files/LS008.pdf
.
ACI Committee 223,
Standard Practice for the Use of
Shrinkage Compensating Concrete,
ACI 223, American Con-
crete Institute, Farmington Hills, Michigan, 1998, 28 pages.
ACI Committee 225,
Guide to the Selection and Use of
Hydraulic Cements,
ACI 225, ACI Committee 225 Report,
American Concrete Institute, Farmington Hills, Michigan,
1999.
Aspdin, Joseph,
Artificial Stone,
British Patent No. 5022,
December 15, 1824, 2 pages.
HOT CEMENT
When cement clinker is pulverized in the grinding mill
during cement manufacture, the friction generates heat.
Freshly ground cement is therefore hot when placed in
storage silos at the cement plant. This heat dissipates
slowly, therefore, during summer months when demand is
high, cement may still be hot when delivered to a ready
Auburn, Historical Timeline of Concrete, AU BSC 314, Au-
burn University,
http://www.auburn.edu/academic/
architecture/bsc/classes/bsc314/timeline/timeline.htm
,
June 2000.
