International Concrete Abstracts Portal

Showing 1-5 of 7 Abstracts search results

Document: 

19-320

Date: 

July 1, 2020

Author(s):

Bruce Menu, Thomas Jacob-Vaillancourt, Marc Jolin, and Benoit Bissonnette

Publication:

Materials Journal

Volume:

117

Issue:

4

Abstract:

The experimental program reported in this paper sought to evaluate the efficiency of a range of curing methods in view of minimizing the evaporation rate at the surface of freshly placed shotcrete and preventing the detrimental consequences of early-age shrinkage. CSA A23.1-14 states that severe drying conditions should be considered to exist when the surface moisture evaporation rate exceeds 0.50 kg/m2/h (0.1 lb/ft2/h). In fact, the environmental conditions that lead to such evaporation rates are regularly experienced on construction sites, requiring that adequate protection of the concrete surface be carried out in a timely manner after placement. This research effort is aimed at quantifying the influence of selected curing methods upon the early-age moisture loss and the resulting shrinkage. The results show that early-age volume change of freshly sprayed shotcrete can be significantly reduced by adequate surface protection. Among the investigated methods, moist curing is found to be the most effective.

DOI:

10.14359/51724624


Document: 

91-M49

Date: 

September 1, 1994

Author(s):

Denis Beaupre, Caroline Talbot, Martin Gendreau, Michel Pigeon, and Dudley R. Morgan

Publication:

Materials Journal

Volume:

91

Issue:

5

Abstract:

ASTM C 672 deicer salt scaling tests were carried out on both dry- and wet-mix shotcretes. Twenty-jive dry-mix shotcretes and eleven wet-mix shotcretes were used to fabricate different test panels. The mix variables included cement type (Types 10 and 30), silica fume, latex (dry-mix process only), polypropylene and steel fibers, set-accelerating and air-entraining admixtures. All test panels were wet-cured for 7 days except two additional panels, one of which was not cured and the other of which was cured with a curing compound. Water containing 2.5 or 3 percent NaCl solutions was used for the scaling tests. The scaling residues were collected and weighed to evaluate deterioration. The mass of scaling residues was found to vary between 0. 1 and 24.0 kgm2. These tests indicate that the scaling resistance of both dry- and wet-mix shotcrete improves with an increase in the air content, and that the use of silica fume generally reduces the mass of scal-ing residues. These tests also indicate that the use of a set-accelerating admixture can significantly reduce the scaling resistance of shotcrete. The use of Type 30 cement and of an air-entraining admixture was found to markedly improve the scaling resistance of dry-mix shotcretes.

DOI:

10.14359/9759


Document: 

JL69-01

Date: 

January 1, 1972

Author(s):

ACI Committee 308

Publication:

Journal Proceedings

Volume:

69

Issue:

1

Abstract:

Curing is defined as the process of maintaining a satisfactory moisture content and a favorable temperature in concrete during hydration of the cementitious materials so that desired properties of the concrete are developed. Two systems of providing the required moisture are explained in detail: (I) main-taining a moist environment by application of water; and (2) prevention of IOSS of mixing water by use of sealing materials. Basic principles of successful curing are outlined, and commonly accepted methods, procedures, and materials are described. Recommendations are given for curing pavements and other slabs on ground; for structures and buildings: and for mass concrete. For each of these categories, methods, materials, time and temperature of curing are recommended. Brief sections comment on curing requirements for precast products, shotcrete, preplaced aggregate concrete, refractory concrete, plaster and other applications.

DOI:

10.14359/11244


Document: 

JL68-25

Date: 

April 1, 1971

Author(s):

ACI Committee 308

Publication:

Journal Proceedings

Volume:

68

Issue:

4

Abstract:

Curing is defined as the process of maintaining a satisfactory moisture content and a favorable temperature in concrete during hydration of the cementitious materials so that desired properties of the concrete are developed. Two systems of providing the required moisture are explained in detail: (1) main-taining a moist environment by application of water: and (2) prevention of loss of mixing water by use of sealing materials. Basic principles of successful curing are outlined, and commonly accepted methods, procedures, and materials are described. Recommendations are given for curing pavements and other slabs on ground; for structures and buildings: and for mass concrete. For each of these categories, methods, materials, time and temperature of curing are recommended. Brief sections comment on curing requirements for precast products, shotcrete, preplaced aggregate concrete, refractory concrete, plaster, and other applications.

DOI:

10.14359/11324


Document: 

JL66-55

Date: 

September 1, 1969

Author(s):

Francis X. Crowley

Publication:

Journal Proceedings

Volume:

66

Issue:

9

Abstract:

Construction of this 150 ft (46 m) diameter dome featured minimum investment in formwork and equipment for precasting and erection. The dome was made of 150 site-precast units, connected by cast-in-place slots of concrete. The slabs, cast on top of each other, used a minimum of formwork and no special curing or handling equipment was required. Steel falsework supported the dome during erection. The dome ring was then prestressed, lifting the dome off the falsework.

DOI:

10.14359/7391


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