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International Concrete Abstracts Portal

Showing 1-3 of 3 Abstracts search results

Document: 

SP-338_04

Date: 

March 1, 2020

Author(s):

Jacob L. Borgerson and Woodward L. Vogt

Publication:

Symposium Papers

Volume:

338

Abstract:

ACI 347.3R-13 provides guidance on the measurement and classification of surface voids (i.e., bug holes) in as-cast formed concrete surfaces. This paper will provide perspective from a testing laboratory on the challenges encountered when asked to perform surface void ratio measurements. Measurements were performed by field technicians and an engineer using the method as described in ACI 347.3R-13, in addition to a modified approach. Based on measurements performed on test areas of a cast-in-place shear wall for a high-rise condominium, it was determined that the between-operator variation and the selected test area significantly impact the classification of the surface. Because the test method does not specify methods for test area location selection or the number of test areas to sample, test results can vary greatly. Specifically, two 24 in. x 24 in. (610 mm x 610 mm) areas that are within 12 in. (300 mm) of each other may possess the highest and lowest classification. Based on field test results, an alternative method is proposed that provides better repeatability between operators and is more time efficient. In addition, based on measuring several different test areas on the same concrete surface, the number of test areas needed to accurately represent the void area of a surface was estimated.

DOI:

10.14359/51724725

Document: 

SP-338_01

Date: 

March 1, 2020

Author(s):

Ward R. Malisch and Heather Brown

Publication:

Symposium Papers

Volume:

338

Abstract:

Bugholes on as-cast surfaces are an aesthetic issue, not a performance issue related to strength, durability, or serviceability. Because they are an aesthetic issue, attempts to evaluate bugholes objectively, with measurements, are not useful. Measuring bugholes using an evenly divided scale or other instrument can reveal their number, individual area, and total area as a percentage of a sample area. But there is no scale or instrument for aesthetic judgments. Thus, matching a mock-up surface with the as-cast surface, although subjective, is a better method for acceptance of surface appearance.

DOI:

10.14359/51724722

Document: 

SP154-15

Date: 

May 1, 1995

Author(s):

Y. Tsukinaga, M. Shoya, R. Sugawara, and H. Nonome

Publication:

Symposium Papers

Volume:

154

Abstract:

In this study, the use of a new permeable sheet was evaluated in making the surface layer of concrete denser, thus improving the performance and durability of the concrete. The application of permeable sheet was confirmed effective in the lowering of water-cement ratio corresponding to the decrease of pore volume; this resulted in the increase of pull-off of tensile strength, rebound number, pulse velocity, and pin penetration resistance in the surface layer. It was also observed that the air bubbles were likely to move from the internal portion to the surface with the expelled flow of water, remarkably reducing bugholes on the concrete surface. The use of new type of permeable sheet improved resistance to freezing and thawing cycling and reduced the depth of carbonation and the ingress of chloride ions. Furthermore, the water tightness was also improved.

DOI:

10.14359/959

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