Gap-Graded Mixes for Cast-in -Place Exposed Aggregate Concrete


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Title: Gap-Graded Mixes for Cast-in -Place Exposed Aggregate Concrete

Author(s): Albert Litvin and Donald W. Pfeifer

Publication: Journal Proceedings

Volume: 62

Issue: 5

Appears on pages(s): 521-538

Keywords: aggregate, architectural concrete, bushhammering, cast-in place concrete, exposed aggregate, field application, gap-graded aggregate, proporioning, sandblasting

Date: 5/1/1965

Attractive uniform exposed aggregate surfaces of cast-in- place concrete may be achieved by the use of low-slump, gap-graded aggregate mixes. These mixes required a high percentage of coarse aggregate and low water-cement ratio, resulting in excellent strength and elastic properties with low creep and drying shrinkage. laboratory tests and field experience indicate that con-cretes with matrix volumes (air, water, cement, and sand) of 45 to 50 percent can be satisfactorily consolidated and will possess excellent architectural characteristics. The importance of special care in such matters as taping of form joints, proper treatment of form ties, adequate vibration, etc., is stressed. Three typical structures are cited in which cast-in-place, gap-graded concrete was used to obtain ex-cellent exposed aggregate surfaces.