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Home > Publications > International Concrete Abstracts Portal
Showing 1-5 of 26 Abstracts search results
Document:
SP148
Date:
September 1, 1994
Author(s):
Editor: V.M. Malhotra
Publication:
Symposium Papers
Volume:
148
Abstract:
In October, 1994, CANMET in association with the American Concrete Institute sponsored a fourth conference on the superplasticizers and chemical admixtures in Montreal. The objective of this conference was to bring to the attention of the concrete community the new developments in chemical admixtures since the last conference in 1989. A total of 25 papers were accepted for publication in this special proceedings from the conference. If you are involved with superplasticizers and chemical admixtures, this special publication is a must. Note: The individual papers are also available as .pdf downloads.. Please click on the following link to view the papers available, or call 248.848.3800 to order. SP148
DOI:
10.14359/14188
SP148-11
C. B. Skaggs, W. G. Rakitsky, and S. F. Whitaker
The impact of superplasticizers and water-soluble polymers, i.e., rheological modifiers, on the rheology and performance of cement-based systems has been investigated. Combinations of water-soluble polymers and superplasticizers can be used to formulate grouts, mortars, and concretes with properties tailored for specific applications. Cement-based systems studied ranged from highly fluid injection grouts to cohesive, flowable concretes suitable for underwater construction and repair applications. Paper demonstrates how the rheology and performance characteristics of cement-based systems can be manipulated using superplasticizers and rheological modifiers. Specifically, the performance properties of a high-molecular-weight polysaccharide produced to fermentation are compared and contrasted with cellulose derivatives. Combinations of water-soluble polymers and superplasticizers can be formulated to produce a continuum of properties ranging from highly fluid, nonseparating grouts to low-slump concretes with enhanced workability and water retention. Choice of the proper combination of superplasticizer and water-soluble polymer is determined by the functional demands of each application.
10.14359/4276
SP148-12
Y. Kasai, S. Hiraishi, K. Tobinai, and K. Osada
Flowing concrete with high flowability prepared with river gravel and crushed stone was investigated for mix proportioning, flowability, strength, shrinkage, carbonation, and freeze-thaw resistance. This concrete has proved highly feasible in terms of cost and performance. The main findings can be summarized as follows: 1) the slump of flowing concrete is capable of sufficiently filling with slight compaction ranges of 24 to 26 cm, corresponding to a flow from 50 to 60 cm, and a differential height less than 8 cm in the box test; 2) flowing concrete with a water-cement ratio from 30 to 60 percent can be made by using a new admixture and with a simple correction of the standard table of mix proportioning; 3) flowing concrete can be produced with specified concrete strengths ranging from 18 to 60 MPa; 4) strength and durability of flowing concrete showed no significant difference from that of AE concrete without any special admixtures.
10.14359/4278
SP148-13
N. Nishiyama, Y. Kasai, N. Yuasa, and Y. Nakata
Flowing concrete is characterized by high flowability, requiring only slight consolidation by vibrating and easy control in a plant. An experimental model structure using flowing concrete was made. Paper deals with placing capability on site and properties of hardened flowing concrete in the structure. Pumpability, flowability, and capability to fill forms were investigated for the fresh flowing concrete, and distribution of compressive strength, carbonation depth, cement content, air permeability, and water absorption were measured. Compressive strength of core samples taken from the model structure and standard cylinder specimens from the plant mixture were approximately 24 Mpa. The average estimated cement content was 333 kg/m 3 and the standard deviation was 15 kg/m 3 within a wall of 3 x 4.2 m. Measured carbonation depth was smaller in the freely flowed portions than in the upper portion of vibrated parts.
10.14359/4280
SP148-14
K. Yokoyama, S. Hiraishi, Y. Kasai, and K. Kishitani
Paper addresses shrinkage and cracking at early ages of highly flowable flowing concrete with a special admixture (unit amount of water of 185 kg/m 3) and of normal high-strength, viscous concrete with high-range AE water-reducing agents (unit amount of water of 170 kg/m 3) under constant air flow. Results are as follows: 1) shrinkage at early ages of flowing concrete and normal high-strength concrete increased with a decrease in water-cement ratio. Shrinkage of normal high-strength concrete varied according to the admixture composition; 2) cracking of both flowing concrete and normal high-strength concrete within a restricting steel frame initiated at an earlier age and became significant with decreasing water-cement ratio. Time and amount of crack initiation of normal high-strength concrete varied according to admixture composition.
10.14359/4282
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The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
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