International Concrete Abstracts Portal

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International Concrete Abstracts Portal

Showing 1-10 of 50 Abstracts search results

Document: 

SP305-48

Date: 

September 1, 2015

Author(s):

Colombo Zampighi

Publication:

Special Publication

Volume:

305

Abstract:

The existing assets need maintenance actions (assessment, repairs and prevention) and related construction works share is increasing in Europe; ISO International Organization for Standardization through its competent Technical Committees has then recently carried out an important activity on reliability, durability and maintenance of concrete structures publishing basic, fundamental Standards concerning these subjects. CEN is planning the revision of the Eurocodes with the same objectives. Italy shows risky contexts, synthetically analyzed, which strongly suggest to improve planning, design, construction and maintenance practices for new and existing concrete structures. Designing for durability and maintenance planning are strictly correlated. This paper, focusing on the above subjects, analyzes specific issues: design guidelines, briefing, maintenance procedure and design validation.


Document: 

SP305-47

Date: 

September 1, 2015

Author(s):

Davide Sirtoli; Sergio Tortelli; Paolo Riva; Maurizio Marchi; Roberto Cucitore; Mankaa Nangah

Publication:

Special Publication

Volume:

305

Abstract:

Calcium-sulphoaluminate cement (CSA) represents an eco-friendly alternative to ordinary portland cement (OPC), thanks to its lower energy consumption, special production process and raw materials. Life-Cycle Analysis (cradle-to-gate) according to ISO 14040 standard series showed a potential for substantial reduction of the environmental impacts, as well as natural resource use. Nowadays, CSA cement is being used more in construction industry thanks to its high early-age compressive strength and shrinkage-compensating behavior. This paper presents concrete mixtures with pure CSA and with OPC-CSA blends both in terms of environmental impact indicators from Environmental Product Declarations, and in terms of mechanical and rheological performance focusing on workability, compressive and flexural strength development, drying shrinkage and dynamic elastic modulus evolution from very early ages.


Document: 

SP305-46

Date: 

September 1, 2015

Author(s):

Federica Selicato; Mauro Moro; Luca Bertolini; and Antonio Nanni

Publication:

Special Publication

Volume:

305

Abstract:

This work is part of a project aiming at investigating a new design approach for sustainable and durable concrete structures, which is based on the use of corrosion-resistant reinforcements in order to allow the use of chloride-contaminated raw materials (especially seawater and recycled concrete aggregate (RCA)). Changes in plain concrete properties, as well as the effects on embedded reinforcement (i.e., black steel and glass fiber reinforced polymer (GFRP)) have been studied. Three types of concrete mixes were produced: the first, a standard one, used as the benchmark; the second where freshwater was substituted with seawater; and, the third where chloride-contaminated RCA and seawater were used. For each mix, features of fresh concrete and mechanical properties of hardened concrete were studied. Further information was obtained by microstructural and chemical analyses. Additionally, durability was studied in terms of concrete and reinforcement resistance to aggressive environments. Results show that concrete is not negatively affected by the introduction of seawater in the mix while RCA plays a more important role in concrete properties. As already well established, the use of corrosive reinforcement, such as black steel, is discouraged in chloride-contaminated concrete because of the high corrosion rates due to pitting phenomena.


Document: 

SP305-45

Date: 

September 1, 2015

Author(s):

Adriano Reggia; Sergio Tortelli; Maurizio Marchi; Massimo Borsa and Giovanni A. Plizzari

Publication:

Special Publication

Volume:

305

Abstract:

Concrete floor on ground represents an important application for concrete use in Italy. Despite their widespread use, a large percentage of concrete floors does not meet the performance requirements in terms of functionality and durability for various reasons; among them, restrained shrinkage cracking and curling represent one of the most important causes of defects. Cracking is mainly due to the drying shrinkage in presence of internal and external restraints, while curling is due to the shrinkage gradient due to the floor thickness. An analytical approach to shrinkage cracking and curling is often overlooked by designers in lieu of the design of contraction joints that allow the cracking of concrete under controlled conditions. Nowadays, the growing needs of concrete floors purchasers in terms of durability and functionality suggests the use of special concretes for flooring. For instance, the use of shrinkage-compensating concretes reduces the number of contraction joints and enhances the concrete slab performances. This study presents the non-linear finite element analysis of a jointless floor made with a shrinkage-compensating concrete obtained with the use of a blend of calcium sulpho-aluminate cement and ordinary Portland cement.


Document: 

SP305-44

Date: 

September 1, 2015

Author(s):

Marco Pepe; Romildo Dias Toledo Filho; Eduardus Koenders and Enzo Martinelli

Publication:

Special Publication

Volume:

305

Abstract:

With the adoption of a policy encouraging the use of recycled aggregates in concrete production, the EU is pursuing the twofold objective of reducing both the demand of natural resources and the environmental impact of the construction industry, that is characterized, as it is well-known, by a significant demand for both energy and raw materials. Therefore, recycling is the main action that can be implemented for turning waste into eco-friendly materials and constituents of newly produced concrete. Particularly, waste concrete can be processed and reused as coarse aggregate, leading to particular kinds of “green concretes” often referred to as Recycled Aggregates Concretes (RACs), in which ordinary coarse aggregates are partially or totally replaced by Recycled Concrete Aggregates (RCAs), while at the same time reducing the so-called Construction and Demolition Waste. However, no well-established theoretical models are capable nowadays of predicting the relevant properties of RACs depending on the actual mixture composition. This paper summarizes the key aspects of a novel physically-based conceptual approach aimed at “designing” RAC mixtures. The formulations proposed in this study are based upon the results achieved from several experimental and numerical investigations carried out for various types of RCAs.


Document: 

SP305-43

Date: 

September 1, 2015

Author(s):

Tarun R. Naik; Fethullah Canpolat and Giacomo Moriconi

Publication:

Special Publication

Volume:

305

Abstract:

Concrete durability-related properties are known to be negatively affected due to expansion and cracking that result from factors such as freezing and thawing actions, alkali-aggregate reactions, sulfate attack, corrosion of the reinforcement, shrinkage, and other similar factors. Durability, and, therefore, sustainability of properly designed and constructed concrete structures depends primarily upon the quality of the materials of construction and other simple, but critical, steps. Concrete construction can last 100 years or more if five simple "steps" are followed: (1) materials selection; (2) structure design; (3) construction; (4) quality management; and, (5) timely evaluation, maintenance, and repairs. This is a holistic approach. Most mistakes are made in not satisfactorily following Steps 4 and 5. Conventional mixture proportioning technique used for production of high-strength concrete does not guarantee long-term durability of concrete. Concrete mixtures must be proportioned to attain desired workability, high-dimensional stability, high-strength, and high-durability related properties; i.e., high-quality concrete (HQC). However, mixture proportioning requirements for HQC must be varied according to the type and expected use of the concrete construction. HQC mixtures must have high-quality constituent materials: durable aggregates, low heat of hydration cement, mineral additives, and chemical admixtures. Furthermore, the mixing water must be minimized (i.e. a low water to cementitious materials ration, W/Cm). A strict quality control is also needed in various aspects of the production of HQC. Research activities conducted at the UWM Center for By-Products Utilization (UWM-CBU), CANMET, and elsewhere, have demonstrated that HQC mixtures can be proportioned to obtain strength in excess of 100 MPa (14,000 psi) and service life of 100 plus years.


Document: 

SP305-42

Date: 

September 1, 2015

Author(s):

Tarun R. Naik; Rakesh Kumar; and Giacomo Moriconi

Publication:

Special Publication

Volume:

305

Abstract:

The need to develop greener concrete is increasing day-by-day with the desire to develop sustainable infrastructures, resource conservation, and contribution to the reduction in the causes of global climate change by reducing carbon footprint of concrete and concrete-making materials, through environmentally-friendly techniques of concrete manufacturing by using recyclable materials, for example post-consumer products. This paper describes the possible roles of post-consumer products namely: used tires, plastics, and glass in the manufacture of greener concrete. Extensive research findings from the studies carried out at University of Wisconsin-Milwaukee Center for By-Products Utilization (UWM-CBU) and elsewhere describing the technology for beneficial use of recycled materials obtained from post-consumer materials in the manufacturing of greener concrete has been presented in this paper. The goal is to not waste such materials because waste is wasted if you waste it; otherwise, it is a resource for a society to be beneficially recycled.


Document: 

SP305-41

Date: 

September 1, 2015

Author(s):

Enzo Martinelli; Joaquim A.O. Barros; Guillermo Etse; Liberato Ferrara; Paula C. Folino; Eduardus A.B. Koenders; and Romildo D. Toledo Filho

Publication:

Special Publication

Volume:

305

Abstract:

Since concrete is the most widely utilized construction material, several solutions are currently being developed and investigated for enhancing the sustainability of cementitious materials. One of these solutions is based on producing Recycled Concrete Aggregates (RCA) from existing concrete members resulting by either industrial processes or demolitions of existing structures as a whole. Moreover, waste resulting from industrial processes other than the building construction (i.e., tire recycling, production of steel, powders resulting from other depuration processes) are also being considered as possible low-impact constituents for producing structural concrete and Fiber-Reinforced Cementitious Composites (FRCC). Furthermore, the use of natural fibers is another option for producing environmentally-friendly and cost-effective materials, depending on the local availability of raw materials. To promote the use of concretes partially composed of recycled constituents, their influence on the mechanical and durability performance of these concretes have to be deeply investigated and correlated. This was the main goal of the EnCoRe Project (www.encore-fp7.unisa.it), a EU-funded initiative, whose activities and main findings are summarized in this paper.


Document: 

SP305-40

Date: 

September 1, 2015

Author(s):

Koji Sakai

Publication:

Special Publication

Volume:

305

Abstract:

The Industrial Revolution in the middle of the 18th century determined mankind’s destiny. The mass production of goods increased the population at an accelerated rate, and, consequently, mankind is facing the risk of natural resources and energy depletion. The greatest challenge to mankind in this century is to ensure the sustainability of the “inhabitants” of the Earth. The basis of mankind’s social and economic activities is infrastructure and buildings. As a result, the construction industry has a far greater influence on the sustainability of mankind and the Earth. Unfortunately, the construction industry has little appreciation of these facts. In order to change from the “old” industry to a “new” industry, the concept of “sustainability” should be introduced as a fundamental idea. The fundamental aspects for considering the sustainability of mankind and the Earth are society, economy, and environment. The essence of the construction industry can be appreciated from these views. There exists interconnection among safety, cost, and environmental impact. In the existing “old” construction engineering, this interconnection is not dealt with systematically. This paper outlines the background on the necessity to introduce a “sustainability” philosophy into the construction sector and proposes a basic framework for sustainability design as a “new” design system


Document: 

SP305-39

Date: 

September 1, 2015

Author(s):

Patricia Kara and Giacomo Moriconi

Publication:

Special Publication

Volume:

305

Abstract:

Advances in concrete technology have led to the development of a new class of cementitious composites with improved mechanical and durability properties, named high performance concrete (HPC). Along with improved performance of HPC there is high cement consumption in the production of this type of concrete which leads to certain increases in CO2 emissions. Ecological and environmental benefits support the use of waste glass powder as supplementary cementing material by decreasing the necessity for landfills, by the reduction of non-renewable natural resource consumption, by the reduction of energy demand for cement production (less cement is needed), and by reducing the greenhouse gas emissions. The present research is focused on design of an HPC using different glass waste cullet ground along with sand into powders which have the most promising effect on the properties of concrete and the effectiveness of application of new generation poly-phosphonic superplasticizers blended with PCE based superplasticizer for HPC concrete. Portland cement is substituted at a level of 20% by mass with glass waste powder which gives the improvement of workability and mechanical properties of the concrete what makes glass powder a valuable Portland cement substitute.


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