International Concrete Abstracts Portal

International Concrete Abstracts Portal

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.

Showing 1-5 of 34 Abstracts search results

Document: 

SP119-21

Date: 

September 1, 1989

Author(s):

T. Nawa, H. Uchi, and Y. Fukaya

Publication:

Symposium Papers

Volume:

119

Abstract:

The influence of alkali sulfate on the viscosity of cement paste containing a superplasticizer was studied by using rotational viscometer. The mechanism of the action of superplasticizer on the fluidity of cement paste was also investigated. A larger amount of superplasticizer was rapidly adsorbed onto C3A and C4AF compared to that on C3S and C2S. The presence of alkali sulfate inhibited the adsorption of superplasticizer on C3A and C4AF, thus permitting increased adsorption on C3S and C2S. The reduction of viscosity of cement paste by superplasticizer is dependent mainly on its adsorption onto C3S and C2S. Therefore, an increase in alkali sulfate leads to an increase in the adsorption of superplasticizer on C3S and C2S, and results in reduced viscosity of cement paste. Excessive amount of alkali sulfate, however, compressed the electric double layer, providing an increase in viscosity of cement paste. Based on the results, it was concluded that there was an optimum alkali sulfate level with respect to the fluidity of cement paste containing the superplasticizer.

DOI:

10.14359/2541


Document: 

SP119-22

Date: 

September 1, 1989

Author(s):

M. Collepardi, S. Monosi, and M. Valenti

Publication:

Symposium Papers

Volume:

119

Abstract:

Purpose was to optimize the type and dosage of superplasticizer in concretes incorporating ASTM Class F fly ash, so that compressive strengths as high as those of superplasticized silica fume concretes could be obtained. Two types of high-range water reducers based on sulfonated naphthalene polymer (SNP) and sulfonated melamine polymer (SMP) both as 40 percent aqueous solution have been used in the presence of fly ash or silica fume to manufacture superplasticized flowing concretes containing ASTM Type I or Type III portland cements. The superplasticizer dosage and the pozzolan addition ranged from the 2 to 4 percent and from 12 to 20 percent, respectively, by weight of cement. The cement factor varied from 255 to 400 kg/m3. The results of the investigation work indicate that only in the presence of ASTM Type III portland cement, superplasticized fly ash concrete can be as strong as the corresponding silica fume concrete, particularly at relatively high cement factors ( ò 300 kg/m3).

DOI:

10.14359/2543


Document: 

SP119-23

Date: 

September 1, 1989

Author(s):

S. Nishibayashi, A. Yoshino, S. Hideshima, M. Takada, and T. Chikada

Publication:

Symposium Papers

Volume:

119

Abstract:

Describes an experimental study of mix designs and characteristics of fresh and hardened superplasticized concrete containing high volumes of blast furnace slag. Results show that using superplasticized concrete in a mix design with a large amount of blast furnace slag allows a lower water content than that of the base concrete, a lower superplasticizer dosage to attain the same increase in slump, and a somewhat lower percentage of fine aggregate. Also, the compressive strength of the hardened concrete was as high as that of the nonsuperplasticized concrete.

DOI:

10.14359/2545


Document: 

SP119-24

Date: 

September 1, 1989

Author(s):

C. Atzeni, G. Mantegazza, L. Massidda, and U. Sanna

Publication:

Symposium Papers

Volume:

119

Abstract:

Results of tests on modified cement mortars admixed with naphthalenesulfonate and acrylic latex used for repairs are presented. Theological and mechanical properties as well as durability have been measured. The combined use of polymer latex and naphthale

DOI:

10.14359/2546


Document: 

SP119-25

Date: 

September 1, 1989

Author(s):

M. Collepardi, R. Khurana, and M. Valente

Publication:

Symposium Papers

Volume:

119

Abstract:

Describes the construction of San Marco dry dock in Italy. Approximately 82,000 m3 of superplasticized concrete with a slump of 250 mm was placed, of which 40,000 m3 were underwater at a depth of 16 m using a tremie system. The concrete was mixed at a central plant and transported to the site where it was pumped for 250 m from a fixed station to the hopper of the tremie located on a floating barge. The presence of heavy reinforcement (steel trestles) made the positioning of the tremie pipe and inspection by divers very difficult. To limit the number of shiftings of the tremie pipe, concrete had to have a very high workability and had to be very cohesive to prevent washing by seawater. Moreover, the specification required an impermeable, sulfate-resistant concrete with a strength of 25 MPa. In the first stage, a slab of 4 m thickness was created by placing overlapping "pizzas" of 45 m3 volume and 15 m diameter. If the concrete was not superplasticized, then the size of the "pizzas" would have been much smaller (approximately 20 m3 volume and 3 to 4 m diameter). After dewatering, the slab was completed with a second pour of self-levelling concrete of 1 m thickness. The use of a superplasticizer helped the contractor complete the job 3 months ahead of schedule.

DOI:

10.14359/2548


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