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Showing 1-5 of 49 Abstracts search results

Document: 

SP305-39

Date: 

September 1, 2015

Author(s):

Patricia Kara and Giacomo Moriconi

Publication:

Symposium Papers

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.

DOI:

10.14359/51688600


Document: 

SP305-38

Date: 

September 1, 2015

Author(s):

Deniz Hamzacebi and Ozkan Sengul

Publication:

Symposium Papers

Volume:

305

Abstract:

The main objective this study was to investigate the effect of waste steel fibers on the mechanical properties of concrete. The steel fibers obtained from waste tires were used, and physical and mechanical properties of these fibers were determined as a first step of the study. Fibers having different aspect ratios were used in concretes at various amounts. A concrete without any fibers was also cast. Compressive, flexural and splitting tensile strengths of the concretes were obtained. Fracture energies were also obtained using a closed-loop testing machine. Results showed that post-cracking strength and toughness of the concretes containing waste steel fibers were significantly increased. Flexural and splitting strength of the concretes were also improved. The experimental results showed that the waste steel fibers recovered from waste tires could be used for the production of steel fiber reinforced concretes. Utilization of waste steel fibers can help to protect environment by reducing the need for steel fiber production. Thus, the reuse of waste fibers in concrete contributes to a more sustainable fiber reinforced concrete production. Since the costs of the waste steel fibers are substantially lower than the commercial steel fibers, more economical steel fiber reinforced concretes can also be obtained.

DOI:

10.14359/51688598


Document: 

SP305-37

Date: 

September 1, 2015

Author(s):

Satoshi Fujimoto

Publication:

Symposium Papers

Volume:

305

Abstract:

Estimation of energy and material input-output during the production and other lifecycle stages is the most basic and repeated procedure to evaluate the environmental impact. Therefore, it is important to develop an accurate, convincing and field-verified model for estimating the material and energy input-output at each lifecycle stages and at each plant or site. With this background, we have been developing energy-use estimation model at concrete production stage. In this paper, we firstly present the unique characteristics of concrete production process in Japan based on our previously proposed model. With this model, we statistically estimate three factors through the field questionnaire survey on ready-mixed concrete plants. The estimation has shown the following characteristics in electric consumption; 1) major manufacturing machineries such as mixer, belt conveyer and blowers are less electric consuming than facilities in constant operation (ex. air compressor), 2) around half of the constant electric consuming facilities can be stopped (at least in some conditions) when concrete shipping is not in queue, which may imply possible options for the reduction of electric energy-use.

DOI:

10.14359/51688597


Document: 

SP305

Date: 

September 1, 2015

Publication:

Symposium Papers

Volume:

305

Abstract:

Editors: Mario Alberto Chiorino, Luigi Coppola, Claudio Mazzotti, Roberto Realfonzo, Paolo Riva

With the dawn of twenty-first century, the world has entered into an era of sustainable development. The main challenge for concrete industry is to serve the two major needs of human society, the protection of the environment, on one hand, and - on the other hand - meeting the infrastructural requirements of the world growing population as a consequence of increase in both industrialization and urbanization. In the past, concrete industry has satisfied these needs well. Concrete is an environmentally friendly material useful for the construction of vast infrastructures. Skyscrapers, highway bridges, roads, water retaining structures and residential buildings are all testimonials to concrete’s use and versatility. However, for a variety of reasons the situation has changed dramatically in the last years. First of all, the concrete industry is the largest consumer of natural resources. Secondly, portland cement, the binder of modern concrete mixtures, is not as environmentally friendly. The world’s portland cement production, in fact, contributes to the earth’s atmosphere about 7% of the total CO2 emissions, CO2 being one of the primary greenhouse gases responsible for global warming and climate change. As a consequence, concrete industry in the future has to face two antithetically needs. In other words how the concrete industry can feed the growing population needs being – at the same time - sustainable?

ACI Italy Chapter has been playing a significant role in the last years in the broad area of concrete technology in Italy and, in particular, in the field of concrete durability and sustainability. ACI Italy Chapter has become increasingly involved in research and development dealing with durability and sustainability issues such as reduction in CO2 emissions, use of recycled materials and innovative products, design of durable structures and maintenance, repair and refurbishment of concrete infrastructures.

In October 2015, the American Concrete Institute Italy Chapter (ACI IC) and the Department of Civil, Chemical, Environmental, and Material Engineering (DICAM) of the University of Bologna sponsored the First International Workshop on “Durability & Sustainability of Concrete Structures” in Bologna (Italy). The workshop was co-sponsored by the American Concrete Institute and ACI Committee 201. The proceedings of the workshop were published by ACI IC as SP305. The proceedings consist of forty-eight refereed papers concerning reduction in green house gases in cement and concrete industry, recycled materials, innovative binders and geopolymers, Life Cycle Cost Assessment in concrete construction, reuse and functional resilience of reinforced concrete structures, repair and maintenance, testing, inspection and monitoring.

Many thanks are extended to the members of the technical paper review panel. Without their dedicated efforts it would not have been possible to publish the proceedings. The cooperation of the authors in accepting reviewers’ comments and suggestions and in revising the manuscripts accordingly is greatly appreciated.

Note: The individual papers are also available. Please click on the following link to view the papers available, or call 248.848.3800 to order. SP-305

DOI:

10.14359/51688467


Document: 

SP305-12

Date: 

September 1, 2015

Author(s):

Liberato Ferrara; Luca Cortesi and Omar Ligabue

Publication:

Symposium Papers

Volume:

305

Abstract:

Advances in concrete technology have led to a widespread use of High Performance Concretes (HPC) with a low water/binder ratio. Those concretes are prone to early age cracking because of the increased autogenous shrinkage, which is normally insignificant for w/b greater than 0.4 and appears mostly in the first days after setting, when the concrete has not reached its full tensile strength, and so it’s one of the principal causes of early age cracking impairing the structure durability. This study aims at quantifying the efficiency of Internal Curing with pre-saturated Light Weight Aggregates (LWA) on the reduction of autogenous shrinkage in HPC. A standard mixture (w/c = 0.3) was tested together with an Internal Cured one, in which a fraction of the normal weight aggregate was replaced by a pre-wetted LWA, to evaluate the differences in the mechanical properties (compressive and tensile strength, elastic modulus) and shrinkage behavior (plastic, autogenous, drying free and restrained shrinkage). In face of a slight decrease of the strength (about 9%) which did not compromise the structural use of the concrete, the pre-wetted LWA led to a 30% decrease of autogenous shrinkage, and a roughly 50% reduction in cracking potential.

DOI:

10.14359/51688572


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