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- Title
Effect of fine fly ash and calcium hydroxide on air void structure in very-early-strength latex-modified concrete.
- Authors
Choi, Pangil; Jeon, Sung Il; Yun, Kyong-Ku
- Abstract
Very-early-strength latex-modified concrete (VES-LMC) was developed for rapid repairs of distresses in concrete bridge decks and pavements, with the emphasis on early-age strength gain so that the repaired bridges and pavements can be opened to traffic within the time frame required in the specifications. However, there are two main concerns in the use of VES-LMC - early-age cracking and poor air void structure. The main objective of this study was to further improve VES-LMC to minimize early-age cracking and improve freeze-thaw durability, which included the use of fine fly ash (FFA) and calcium hydroxide (CH). Laboratory experiments were conducted on VES-LMC materials with cement replaced with FFA as well as CH, and various tests performed. Early-age drying shrinkages of VES-LMC containing both FFA and CH in the amounts evaluated in this study were smaller than that of VES-LMC with no replacements. It is expected that the use of FFA and CH in the range evaluated in this study will reduce the cracking potential of VES-LMC. Overall, the replacement of cement with FFA and CH improved the characteristics of entrained air void system, which will enhance the durability of VES-LMC against freeze-thaw damage. Scanning electron microscope and energy dispersive spectroscopy analysis indicate the primary mechanism of the generation of small sized air voids in concretes containing adequate amount of FFA and CH is the gas formation reaction between citric acid solutions and CH during concrete mixing. It is expected that the inclusion of adequate amounts of FFA and CH in VES-LMC will improve the performance of repaired bridge decks and pavements in terms of reduced cracking and improved freeze-thaw durability.
- Subjects
FLY ash; CALCIUM hydroxide; LATEX; REINFORCED concrete; FREEZE-thaw cycles; CRACKING of concrete; ENERGY dispersive X-ray spectroscopy; SCANNING electron microscopy
- Publication
Canadian Journal of Civil Engineering, 2015, Vol 42, Issue 10, p797
- ISSN
0315-1468
- Publication type
Article
- DOI
10.1139/cjce-2015-0013