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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 14 Abstracts search results
Document:
19-442
Date:
November 1, 2020
Author(s):
Thuc Nhu Nguyen, R. Emre Erkmen, Leandro F. M. Sanchez, and Jianchun Li
Publication:
Materials Journal
Volume:
117
Issue:
6
Abstract:
Alkali-silica reaction (ASR) is one of the most harmful distress mechanisms affecting concrete infrastructure worldwide. ASR is a chemical reaction that generates a secondary product, which induces expansive pressure within the reacting aggregate material and adjacent cement paste upon moisture uptake, leading to cracking, loss of material integrity, and functionality of the affected structure. In this work, a computational homogenization approach is proposed to model the impact of ASR-induced cracking on concrete stiffness as a function of its development. A representative volume element (RVE) of the material at the mesoscale is developed, which enables the input of the cracking pattern and extent observed from a series of experimental testing. The model is appraised on concrete mixtures presenting different mechanical properties and incorporating reactive coarse aggregates. The results have been compared with experimental results reported in the literature. The case studies considered for the analysis show that stiffness reduction of ASR-affected concrete presenting distinct damage degrees can be captured using the proposed mesoscale model as the predictions of the proposed methodology fall in between the upper and lower bounds of the experimental results.
DOI:
10.14359/51728125
17-317
May 1, 2019
Sergio Botassi dos Santos, Kennedy Leandro de Souza Neves, and Estevão Alencar Bandeira
116
3
This paper presents a real case study concerning the analysis of the cracking risk of a large reinforced concrete slab-on-ground with 9.84 in. (250 mm) of thickness and approximately 9257 ft2 (860 m2) of area. It was designed to prevent effects of severe environment conditions over the life span as thermal and drying shrinkage. This slab is a pool floor without expansion joint—jointless—to avoid leakage and early deterioration of the structure. The main properties were initially estimated based on the thermal structure behavior to evaluate the volume change effect from early ages to long-term effects. The proposed solutions to reduce the volume change effects of concrete were carried out in three parts: improvements in structural design; optimization of the concrete mixture; and adjustments in the construction process. After the concrete placement, the solutions proved to satisfactorily prevent cracks, thus ensuring proper performance of the pool.
10.14359/51712267
15-347
November 1, 2016
Yannick Vanhove and Kamal Henri Khayat
113
Ensuring adequate stability is critical in flowable and lean concrete prone to bleeding and segregation. This paper proposes a forced bleeding test method that can be used to determine the ability of fresh concrete to retain some of its mixing water under a pressure gradient across a drainage surface. The investigated concrete was proportioned with a water-cement ratio (w/c) of 0.55 to 0.65 with slump values varying between 70 and 240 mm (2.75 and 9.45 in.). The proposed forced bleeding test has an overhead pressure of 138 kPa (20 psi) with the pressure maintained for 1 minute. This short test duration and relatively low overhead pressure yielded better results than higher testing pressure gradients or longer test durations. Forced bleeding test results showed good correlations between the rate of forced bleeding at 1 minute and physical tests to evaluate stability. Physical tests included the determination of external bleeding for 2 hours, the measurement of coarse aggregate distribution along hardened concrete samples, as well as the variation in electrical conductivity along concrete sample height during the dormant period of cement hydration to evaluate homogeneity.
10.14359/51689240
14-276
July 1, 2016
Cameron D. Murray, Richard A. Deschenes Jr., and W. Micah Hale
4
Alkali-silica reaction (ASR) is a reaction that occurs over time in concrete between the highly alkaline cement paste and reactive noncrystalline amorphous silica, which is found in many common aggregates. The reaction can lead to expansion and severe damage in concrete members. One method to mitigate ASR expansion is to use a penetrating sealer such as silane. A set of columns located in a food preparation facility was treated with silane and a complimentary laboratory study was performed. A cleaning regimen involving application of an alkaline cleaner was employed at the facility, followed by rinsing with hot, pressurized water. The purpose of this research is to evaluate the effectiveness of silane when used in this alkaline environment. The research shows that silane was effective at reducing expansion in new concrete, less so when the pH of the environment is high; other measures will be needed for previously cracked concrete.
10.14359/51688982
107-M45
July 1, 2010
Jose F. Munoz, M. Isabel Tejedor, Marc A. Anderson, and Steven M. Cramer
107
Deleterious clay minerals often enter concrete as coatings on aggregates; the impacts of the certain clays introduced by this mechanism is the subject of this study. The effects of different clay properties, including cation exchange capacity (CEC) and the nature of the exchangeable cations on concrete, were measured. The material selected for this research was an igneous clean coarse aggregate which, for purposes of repeatability and experimental control, was lab-coated with four different clay suspensions (kaolin, illite, sodium montmorillonite, and calcium montmorillonite). The coated aggregate was then used to make concrete test specimens. The results clearly show that the impact of the clays is not only a function of the CEC of the clay but also of the nature of the exchangeable cation.
10.14359/51663865
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