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  • 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.

International Concrete Abstracts Portal

Showing 1-5 of 50 Abstracts search results

Document: 

SP305-23

Date: 

September 1, 2015

Author(s):

Jinxia Xu; Yalong Cao; Hongyou Shan; Li Tang; Yi Xu

Publication:

Symposium Papers

Volume:

305

Abstract:

A novel technique to upgrade the mortar durability by surface coating layer formation and densification using an electrodeposition method is suggested here. In this technique, the SiO32- ions as key raw materials are applied. Under the applied electric field, they are transported into the pores to react with Ca(OH)2 to promote the additional C-S-H gel formation, which induces the densification of mortar. Besides, the accelerated hydrolytic reaction of SiO32- ions, and the reaction of SiO32- ions in the outer electrolyte with the leached Ca2+ promote C-S-H/silica gel precipitation on the mortar surface. Furthermore, by a comparative experiment, it has been found that this technique can moderately increase the compressive strength and flexural strength of electrodeposited mortar sample. Also, the chloride diffusion into the electrodeposited mortar sample is notably decreased, which demonstrates the effectiveness of this electrodeposition technique in upgrading the durability.


Document: 

SP305-27

Date: 

September 1, 2015

Author(s):

Lisa E. Burris; Prasanth Alapati; Robert D. Moser; M. Tyler Ley; Neal Berke; and Kimberly E. Kurtis

Publication:

Symposium Papers

Volume:

305

Abstract:

Cement production accounts for 1650 million metric tons of yearly global CO2 emissions [1], making it one of the largest contributors to worldwide CO2 emissions. One pathway to reducing CO2 emissions associated with concrete construction is through the use of alternative cementitious materials and binders (ACMs) such as calcium sulfoaluminate, calcium aluminate, and alkali-activated binders. These materials often require lower production temperatures than ordinary portland cements (OPC) and have lower calcium contents, reducing the emissions associated with CO2 released from calcium carbonate during calcination. Most ACMs are not new materials, but past uses have been primarily limited to small-scale applications such as pavement repairs and little field experience exists concerning their long-term durability in highly-trafficked structures such as pavements and bridge decks. This paper presents outcomes after the first year of a U.S. Department of Transportation effort to increase understanding of how to best utilize ACMs in new transportation infrastructure throughout the U.S. and presents the challenges in evaluating the durability of these materials using laboratory testing methods developed for use with OPC concrete. These concepts form the foundation for continued research and broader implementation of ACMs in transportation infrastructure.


Document: 

SP305-13

Date: 

September 1, 2015

Author(s):

Liberato Ferrara; Isaia Albertini; Ravindra Gettu; Visar Krelani; Simone Moscato; Francesco Pirritano; Marta Roig Flores; Pedro Serna Ros and Swathi M. Theeda

Publication:

Symposium Papers

Volume:

305

Abstract:

Self-healing cementitious composites are a broad category of smart construction materials to which strong and highly qualified research efforts are currently being devoted worldwide, with the aim of providing a sound scientific background to their consistent, and – design-wise – “consciously safe”, use in the engineering practice. Tailored additions can be employed to enhance the self-healing capacity, among which the so-called crystalline admixtures, play a prominent role. Crystalline admixtures consist of proprietary active chemicals, which, because of their hydrophilic nature, react with water and cement particles in the concrete to form calcium silicate hydrates, increasing the density of the CSH phase, and/or pore-blocking precipitates in the existing micro-cracks. The mechanism is analogous to the formation of CSH and the resulting crystalline deposits become integrally bound with the hydrated cement paste, thus contributing not only to a significantly increased resistance to water penetration but also to the healing of the existing damages and cracks. This paper summarizes the results of a wide experimental investigation jointly performed by Politecnico di Milano (Italy), Indian Institute of Technology Madras, Chennai (India) and Universitat Politecnica de Valencia (Spain) to assess the effectiveness of different commercially available crystalline admixtures on the self-healing capacity of cement based materials.


Document: 

SP305-03

Date: 

September 1, 2015

Author(s):

Francesca Albani

Publication:

Symposium Papers

Volume:

305

Abstract:

Architectural works by major architects from the twentieth century have often been subject to restoration campaigns intended to redeem them from decay (sometimes from neglect) in order to present them as “monuments” of the twentieth century. In particular, in architecture in which exposed reinforced concrete plays a key role in architectural, figurative, symbolic and cultural terms, the theme of repairing/replacing the concrete cover is a fundamental issue in the restoration project. Analyzing the methods, materials and techniques of intervention used in several campaigns of restoration of buildings built before World War II (the church of Notre-Dame du Raincy by Gustave and Auguste Perret in France and Rudolf Steiner’s Goetheanum at Dornach near Basel in Switzerland) or after the War (Figini and Pollini’s housing built in Milan and the Olivetti Factory in Crema by Zanuso) provides an opportunity to identify best practices, and also critical factors and weaknesses of the different approaches used in the restoration of these buildings from the 1980s to the present.


Document: 

SP305-02

Date: 

September 1, 2015

Author(s):

Federico M. Aguayo; Thano Drimalas; Kevin J. Folliard

Publication:

Symposium Papers

Volume:

305

Abstract:

In this paper, the carbonation resistance of various concrete mixtures incorporating supplementary cementitious materials exposed to atmospheric CO2 concentration in Austin, Texas, USA, was investigated. The paper provides a detailed description on the creation of an outdoor exposure site to place and monitor concrete specimens under ambient air exposure conditions. Two exposure conditions were investigated, including specimens that were placed outdoors unsheltered and in sheltered environments protected from direct rainfall. The depth of carbonation was measured after 730 days of exposures. Additionally, relative humidity (RH), temperature, and environmental CO2 concentrations in the air were also monitored at the site to provide a general indication of the conditions at the exposure site. Various factors were investigated including water-cementitious materials ratio, type and dosage of supplementary material, and cement type. The depth of carbonation of mixtures without supplementary material was moderate. The addition of supplementary material significantly increased the carbonation depth, especially when replacement levels exceeded 30% of cement by mass. The results were exacerbated for those concrete specimens that were placed outdoors but sheltered from direct rainfall.


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