ACI Global Home Middle East Region Portal Western Europe Region Portal
Email Address is required Invalid Email Address
In today’s market, it is imperative to be knowledgeable and have an edge over the competition. ACI members have it…they are engaged, informed, and stay up to date by taking advantage of benefits that ACI membership provides them.
Read more about membership
Learn More
Become an ACI Member
Topics In Concrete
Home > Publications > 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 90 Abstracts search results
Document:
SP132-40
Date:
May 1, 1992
Author(s):
J. Ambroise, S. Martin-Calle, and J. Pera
Publication:
Symposium Papers
Volume:
132
Abstract:
After calcination at 650 to 850 C, kaolinitic clays show an interesting pozzolanic property. Thermal activation leads to metakaolin, an amorphous phase which is very reactive. In this study, different clays were tested with various granular sizes and calcination parameters. The pozzolanic properties were investigated using metakaolin-lime mixtures by the evaluation of both the mechanical strength and combined lime. The mineralogical composition, particle size distribution, and degree of amorphousness were the main factors affecting the pozzolanic activity of calcined clays. Influence of the pozzolanic activity on the mechanical and durability properties of concrete was established from test results on blended portland-metakaolin cements.
DOI:
10.14359/2133
SP132-42
T. Marwan J. Pera, and J. Ambroise
When heated at 800 C for 5 hr, Indonesian laterites showed good pozzolanic activity. The kaolin content of the material is the main cause of pozzolanicity, as indicated by the lime reactivity. Blended portland cements containing 20, 30, 40, and 50 percent of calcined laterite admixture were studied. Concretes were made with such cements and placed in aggressive solutions: seawater, acetic acid, and sulfuric acid. The best results were obtained with a cement containing 30 percent of calcined laterite admixture.
10.14359/2144
SP132-55
G. G. Carette and V. M. Malhotra
Presents results of an investigation dealing with the long-term strength of silica fume concrete. Three series of concrete mixtures with and without silica fume were made with water-cementitious ratios from 0.25 to 0.40. The replacement level of portland cement with silica fume was kept constant at 10 percent. Test specimens were cast from each mixture to determine the compressive and flexural strengths of concrete at up to 3.5 years under both water-curing and air-drying conditions. The test specimens were also subjected to the determination of microstructure, carbonation, and weight changes with time. It is concluded that, under water-curing conditions, both the control and silica-fume concretes show gain in strength with age, with both concretes reaching similar strength levels after 3.5 years. However, continuous air-curing adversely affects the long-term compressive strength development of both types of concrete. This effect is considerably more marked for silica-fume concrete than for the control concrete, especially at w/c + sf of 0.30 and 0.40.
10.14359/2383
SP132-56
P. H. Laamanen, K. Johansen, B. P. Kyltveit, and E. J. Sellevold
It is well known that curing concrete at elevated temperatures reduces the final compressive strength. The reduction depends on the temperature regime as well as the concrete composition. This program was based on recent data indicating that concrete containing condensed silica fume suffers less strength loss if a strength of about 10 MPa is reached at 20 C before heating. In this investigation, concrete characteristics were w/c + s = 0.30, 0.45, and 0.60 with and without 8 percent condensed silica fume. The temperature regime was to transfer specimens at 40 and 60 C, after delay times at 20 C. The delay times corresponded to strengths of about, 0, 3, 6, 9, 12, and 16 MPa. After 6 days, all specimens were cooled to 20 C and tested at 28d. The results show that the delay period had no significant influence on the final strength, except for the specimens with zero delay. The rest suffered some strength reduction compared to 20 C references, about 15 percent for w/c + s = 0.60, and less than 10 percent for the others. The reductions at 60 C were slightly greater than at 40 C. Concretes containing condensed silica fume generally suffered the smallest strength reductions.
10.14359/2394
SP132-57
J. Lindgard and S. Smeplass
In normal strength concretes, the compressive strength is limited by the strength of the binder and the binder-aggregate bond. In high-strength concretes, however, the binder strength and the bond may be fully comparable to the strength of the aggregate. This fact may lead to the conclusion that the strength of high-strength concretes may be improved by replacing an ordinary aggregate type with a high-strength aggregate. A number of aggregate types have been combined with high-strength binders to evaluate the impact of the aggregate strength on concrete compressive strength. The significance of the aggregate strength has been compared with the effect of the cement type and the use of silica fume. According to the obtained results, the impact of the aggregate strength on the strength of high-strength concrete is limited, compared to the binder type, while the difference in E-moduli between the different aggregate types is fully reflected in the concrete E-moduli. This contradiction is explained by a hypothesis based on stress concentrations due to the difference in rigidity between the binder and aggregate.
10.14359/2404
Results Per Page 5 10 15 20 25 50 100
Edit Module Settings to define Page Content Reviewer