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Home > Publications > International Concrete Abstracts Portal
Showing 1-5 of 46 Abstracts search results
Document:
CI4107DU
Date:
July 1, 2019
Author(s):
Chongjiang Du
Publication:
Concrete International
Volume:
41
Issue:
7
Abstract:
The article discusses the use of magnesium oxide-based shrinkage-compensating concrete (MgO concrete) in construction of roller-compacted concrete (RCC) dams. The delayed autogenous expansion of MgO concrete roughly matches the shrinking process of dam mass concrete as its temperature drops and helps to prevent thermal cracking. Using MgO concrete in RCC dams can result in simplification of temperature control measures as well as shorten the construction period.
CI4002Bass
February 1, 2018
Randall P. Bass and Gary Horninger
40
2
Key features of roller-compacted concrete (RCC) dams are highlighted, using various dam types as examples. Topics include lift interfaces, facing systems, spillways, intakes and outlets, internal galleries, and joints. Test sections are recommended for training and to demonstrate that the systems, methods, and equipment proposed for a project will meet project specifications.
CI3811Du
November 1, 2016
38
11
An arch-gravity roller-compacted concrete (RCC) dam on the Gomal River, Pakistan, was built from 2008 to 2012. Temperature control measures were required during construction to prevent thermal cracking of RCC in hot weather. The article provides detailed descriptions of these measures, specifically the precooling of aggregates and mixing water and post-cooling of the placed RCC.
CI3103Yang
March 1, 2009
Lei Yang and Jonathan J. Shi
31
3
Longtan Dam is a roller-compacted concrete (RCC) dam currently under construction in Guangxi Province, China. Due to its height and large volume, there are a great number of horizontal construction joints, and many of them may become cold joints during construction because weather conditions in the region often disrupt construction. In this study, different methods for treating layer joints in the Longtan RCC project were analyzed. The objective was to identify an efficient, easy-to-use treatment method that can meet the bonding requirements. The findings will help expedite construction and ensure high quality.
SP235-09
March 22, 2006
A.A. Ramezanianpour, A. Hassankhani, and A.M. Ramezanianpour
Symposium Papers
235
Heat of hydration of cement and resulting thermal gradient has a great influence on the quality of concrete and concrete structures particularly in the mass concrete for dams. In roller compacted concrete (RCC) method for dam construction, surface of concrete layers are very large in comparison with thickness of the layers. Therefore the thermal condition in the center of layers is almost adiabatic in horizontal direction. t means that, the generated heat of hydration mostly flows in the vertical direction and a great proportion of heat dissipates through the upper face of the layer before the next layer is placed. Low thermal conductivity of concrete layers has a great influence on the dissipation of generated heat. Thermal gradient induced by generated and remaining heat in the layers can cause thermal cracking in RCC dams which have no post-cooling system. In this investigation a laboratory model is set up to optimize the layer thickness and required time for dissipating of generated heat and controlling thermal cracking. The laboratory model consists of a 90x90 cm cylinder filled with 3 layers of concrete with 30cm thickness each layer. In this simulation the variables were the thickness of layers and the exposure time for each before placing the subsequent layer. Temperature variations were recorded at the center of each layer and at different distances from the center of the laboratory model. From the results of this research, the thickness of the layers and their related exposure time were determined for various concrete mixtures in order to minimize the heat problem and thermal crack prevention. The proposed guide for placing concrete in RCC dams seems to be beneficial for the construction of such dams under various conditions.
DOI:
10.14359/15860
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