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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 71 Abstracts search results
Document:
SP126-40
Date:
August 1, 1991
Author(s):
A. J. Majumdar and P. L. Walton
Publication:
Symposium Papers
Volume:
126
Abstract:
Fiber cement composites developed commercially as replacements for asbestos cement have been under investigation at the Building Research Establishment for a number of years. These include composites containing fibers of glass, polyvinyl alcohol, and cellulose. The suitability of other fibers, including some natural vegetable fibers for cement reinforcement, has also been examined in the past. A summary of the results obtained in some of these studies is presented. Among the composites just mentioned, glass fiber reinforced cement has received the most attention at BRE for historical reasons. In this study, different types of cement--portland, high-alumina, supersulfated, etc.--as well as portland cement modified by pozzolans and polymers--were used. For some of these composites, important mechanical properties after natural weathering for up to 20 years have been determined recently. A review of this work is given, and the results are analyzed in terms of mechanisms that are considered to be important in determining the long-term durability of these materials. It has not been possible yet to devise realistic accelerated aging tests for many of the new fiber cement composites to predict their long-term properties.
DOI:
10.14359/2370
SP126-42
D J. Hannan
Natural weathering, dry air storage, and water curing for long periods of time will have different effects on matrix properties in most fiber reinforced cements. Changes in matrix properties are shown to effect the cracking stress of the composite that will change with time and curing conditions, regardless of changes in fiber properties. The reasons for the differences in the critical fiber volume in uniaxial tension and flexure are explained, and examples are given of 10-year tests on thin cement-based sheets containing networks of fibrillated polypropylene film in which the effects are demonstrated. It is shown that the manufacturer of the composite needs to have an understanding of these problems if the component is to remain ductile for many years in natural weathering conditions.
10.14359/2378
SP126-43
Mitsunori Kawamura and Shin-Ichi Igarashi
The long-term durability of glass fiber reinforced (GFR) mortars and concretes manufactured by the premixing method was investigated. Microhardness measurements and the quantitative back-scattered electron image (BSE) analysis were made in the regions around glass fiber strands embedded in the cement paste. Changes of flexural strength and toughness in the GFR mortars with age were found to be related to the features of microstructure in the interfacial regions. The toughness of the GFR mortars decreased with age in response to the increase in microhardness at the immediate vicinity of strands and around 70 to 100 æm from the interface. The solidification in the regions around 70 to 100 æm from interface, as well as the formation of the hydration products in the spaces among the glass filaments, appear to relate to reduction in toughness in GFRC composites.
10.14359/2388
SP126-67
F. Massazza and G. Oberti
Compared to portland cements, pozzolanic cements can better resist various aggressive agents, such as pre and acidic waters, chlorides, and sulfates. Furthermore, they can also prevent expansion caused by alkali-aggregate reactions. Provided that concretes of the same strength are compared, the carbonation depth of pozzolanic cements is similar to that of portland cements. In Italy, where they have extensively been used for the construction of buildings and civil engineering works, pozzolanic cements accounted for over 15,000,000 t of cement production in 1989. This is, however, indirect evidence of the durability associated with this type of cement. Direct evidence is actually provided by many Italian dams built over 40 years ago, which, despite the heavy and manifold environmental conditions that they have been subjected to yearly, still show good serviceability.
10.14359/3641
SP126-70
M. Marosszeky, J. G. Yu, and C. M. Ng
Discusses the findings from the study of bond that forms a part of a major laboratory evaluation of the characteristics of repair materials carried out in the Building Research Centre. The important properties of repair patching materials that can affect the bond of a repair, such as shrinkage, thermal movement, compressive, shear, and tensile strength, are evaluated. The importance of surface preparation is also discussed.
10.14359/3765
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