International Concrete Abstracts Portal

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

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.

The effects of substituting 5-20% fly ash for slag and adding 0.10~0.30% polypropylene fiber on the physical and mechanica1 properties, shrinkage and cracking behaviors, water permeability and porosity of alkali-activated ground granulated blast furnace slag cement paste and mortar are studied. The results show that replacing 5-15% fly ash for slag in the alkali-activated slag cement paste and mortar increased the flexural strength, though the compressive strength were slightly decreased. When the replacement of fly ash for slag was increased to 20%, both the flexural and compressive strengths of the paste and mortar begin to decrease. The early shrinkage and cracking were reduced by the fly ash replacement. Adding 0.10~0.30% polypropylene fiber decreased both the flexural and compressive strengths, whereas the shrinkage, especially the cracking of the alkali-activated slag cement was greatly reduced.

The research aims at studying an innovative construction system (called S.E.Con. System1 - Sustainable Ecological Construction System) to realize sustainable buildings, having both acoustic and thermal high performance, in which the seismic-resistant structural elements are small reinforced concrete walls widely spread on the perimeter of the building and where all vertical structural and secondary elements (infill panels) are constructed using shotcrete. The results of experimental tests on a single story sample building and on structural walls, aimed to assess the structural, acoustic, and thermal insulation performances of the devised system, demonstrate that the system appears suitable for high seismicity areas, and that thermal and acoustic criteria set for passive constructions are met. Finally, an evaluation of the carbon footprint (CFP) has also been carried out, demonstrating a reduction of about 30% in the CFP of the construction system with respect to traditional construction systems.

The demand for the development of a more efficient and durable transportation infrastructure is among the top priorities of highway authorities worldwide. In the United States, the economic impact of steel corrosion for concrete highway bridges is estimated to exceed 15 percent of total annual costs. Degradation affecting steel reinforced concrete (RC) bridge superstructures exposed to harsh environmental conditions is not limited to decks, but includes railings and barriers and can significantly compromise their crashworthiness. Glass fiber reinforced polymer (GFRP) is highly suitable for reinforcing concrete structures subjected to corrosive environments and a number of projects have demonstrated its viability as an alternative reinforcement for bridge decks. Until recently, most traffic barriers using GFRP bars were vertical-faced systems. However, the impact time duration of vertical-faced barriers is shorter causing higher peak forces to be transferred to vehicle occupants. Nowadays, GFRP manufacturers can produce standard bar bends which can be used for the reinforcement of safety-shaped concrete railings and barriers. The implementation of GFRP bar bends requires some changes in the current design philosophy for railings and barriers. Whereas the overall goal of the research program is to make the technology of concrete bridge reinforcement with composites available to bridge owners and professionals, this paper provides the principles for the design of safety-shaped GFRP-reinforced concrete railings/barriers.