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International Concrete Abstracts Portal

Showing 1-5 of 31 Abstracts search results

Document: 

SP68-13

Date: 

January 1, 1981

Author(s):

K. Kishitani, H. Kasami, M. lizuka, T. Ikeda, Y. Kazama, and K. Hattori

Publication:

Symposium Papers

Volume:

68

Abstract:

A series of laboratory and field studies were conducted to determine the engineering properties of concretes containing a sulphonated naphthalene formaldehyde condensate superplasticizer (MIGHTY). In laboratory studies, conventional and superplasticized concretes with slumps from 12 to 21 cm were placed into moulds for full-size, single-frame models of reinforced concrete structures for measurements of form pressures and response to internal vibration as well as tests on the strengths and drying shrinkage in finished structures. Superplasticized concrete indicated greater response to vibration than and equal form pressures to conventional low-slump concrete. Higher core strengths were obtained with superplasticized concrete than with conventional concrete, while no change was observed in drying shrinkage with addition of the admixture. Further studies were conducted on ordinary and lightweight aggregate concretes in the construction of a ten-storey, reinforced concrete structure. Higher fluidity was observed in super-plasticized concrete, while the same trends as in the laboratory were observed regarding form pressure and core strengths. The test results on pumpability indicated that superplasticized lightweight aggregate concrete can be pumped at a lower pressure to a height of fifty meters without adversely affecting concrete properties.

DOI:

10.14359/6474


Document: 

SP68-14

Date: 

January 1, 1981

Author(s):

Walter Lukas

Publication:

Symposium Papers

Volume:

68

Abstract:

Concretes display a chloride penetration which is dependent on several factors. The water-cement ratio exerts the most influence, the penetrated chloride content decreasing with a decrease in the ratio. High quality concrete with a low water-cement ratio has a considerably smaller chloride content than otherconcretes of the same consistency. Superplasticized concrete has a smaller tendency to absorb chloride than untreated concretes of the same water-cement ratio. Cements with pozzolanic additions show increased resistance to chloride diffusion into the concrete. If concretes are air entrained there is a considerable chloride concentration in the upper-most zone. This is due both to the greater segregation tendency and to the air voids themselves.

DOI:

10.14359/6475


Document: 

SP68-09

Date: 

January 1, 1981

Author(s):

M. Collepardi, M. Corradi, and M. Valente

Publication:

Symposium Papers

Volume:

68

Abstract:

Compressive strength and restrained expansion tests were carried out on concretes containing naphthalene sulphonic formaldehyde type superplasticizer and an expansive agent based on processed lime. At constant expansive agent content, the higher the early strength (1 day) the higher was the restrained expansion. Therefore, if the superplasticizer is used to increase the early strength by reducing the water/cement ratio, it is possible to reduce the content of the expansive agent to obtain the same de-gree of expansion. On the other hand, if the superplasticizer is used to reduce both water and cement, and therefore the drying shrinkage, less expansive agent would be required for shrinkage compensation purposes. The results of the present work indicate that the combination of a superplasticizer and an expansive agent may be more advantageous than the use of expansive agent alone.

DOI:

10.14359/6470


Document: 

SP68-27

Date: 

January 1, 1981

Author(s):

M. Collepardi, M. Corradi, and M. Valente

Publication:

Symposium Papers

Volume:

68

Abstract:

More than twenty naphthalene sulphonated formaldehyde condensates have been synthesized with various degrees of polymerization. This was evaluated by viscosity measurements of the polymer in water solution. Polymer adsorption, zeta potential, fluidity and compressive strength of cement mixtures have been examined as a function of the degree of polymerization and the polymer dosage. Polymer adsorption, zeta potential and fluidity increase by increasing the polymer dosage in the range of 0.25 -2.00 % by weight of cement. Polymer adsorption, zeta potential, fluidity increase by increasing the degree of polymerization. However, above a certain degree of polymerization all the above mentioned properties do not change further. Cement particles adsorb the polymer molecules and this causes an increase in the electrical charge on the cement surface. This results in a better dispersion of cement particles and a more fluid system. However, even if there is a certain interaction between fluidity and zeta potential, the latter is not the only parameter controlling the fluidity of the system. At the same water/cement ratio, by increasing the degree of polymerization the strength is, in general, slightly increased and this seems to be related to a better dispersion of cement particles.

DOI:

10.14359/6488


Document: 

SP68-12

Date: 

January 1, 1981

Author(s):

E. Okada, M. Hisaka, Y. Kazama, and K. Hattori

Publication:

Symposium Papers

Volume:

68

Abstract:

Freeze-thaw resistance in terms of the durability factor, DF, was investigated with concretes containing varying dosages of p-sodium naphthalene sulfonate formalin high condensate (p-NSFHC) superplasticizer (MIGHTY) at water-cement ratios from 0.25 to 0.55 and the addition of vinsol resin soap to obtain air contents up to 4 percent, with a view to to correlating these to the spacing factor, L. It was established that the failure boundary curve can be described as a function of water-cement ratio and air content in hardened concrete. The effect of the camp ressive strength of the volumes of water and ai r vo ids in concretes was examined. The effect of air volume on strength was found to be half that of the same volume of water. It was found that vinsol resin is a satisfactory air entraining agent for use in concretes superplasticized with B-NSFHC.

DOI:

10.14359/6473


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