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Showing 1-5 of 942 Abstracts search results

Document: 

SP-355_32

Date: 

July 1, 2022

Author(s):

Vincenzo Romanazzi, Marianovella Leone, Francesco Tondolo, Alessandro Pasquale Fantilli, Maria Antonietta Aiello

Publication:

Symposium Papers

Volume:

355

Abstract:

The huge quantity of natural aggregates extracted every year and used in the concrete industry is causing harmful consequences on biodiversity, water turbidity, water table level and landscape, and global warming as well. In this context, many studies focused on the possibility to use waste tyre recycled aggregates as partial replacement for stone aggregates in concrete production. Generally, it has been observed that several mechanical properties, such as compressive strength and modulus of elasticity, significantly decrease when rubber content is increased. On the other hand, rubberized concrete (RuC) showed a more ductile behavior than ordinary Portland cement concrete, in addition to a greater damping and energy dissipation capacity. In this paper, the compressive and flexural strength, water permeability, and thermal conductivity of five concrete mixtures with increasing percentages of rubber particles as a partial replacement for natural aggregates have been investigated. As a result, a reduction in compressive strength has been observed only in RuC mixtures with substitutions greater than 12% of the total aggregates, whereas the flexural strength remained roughly constant. Moreover, the results of water permeability and thermal conductivity tests showed respectively a decrease in water penetration and an improvement of the concrete thermal isolation due to the presence of rubber particles.


Document: 

SP-355_24

Date: 

July 1, 2022

Author(s):

Daria Jóźwiak-Niedźwiedzka, Alessandro P. Fantilli

Publication:

Symposium Papers

Volume:

355

Abstract:

Various types of dispersed reinforcement in the form of thin fibers are known to improve the toughness of cement-based materials. In cement-matrix composites, the application of sheep wool, which is an ecological material, annually renewable and completely recyclable, perfectly fits into green and sustainable development. As the wool tends to be damaged by an alkaline environment, this paper describes the influence of the cement type on the performance of sheep wool reinforced mortars. Hence, ordinary Portland cement (CEM I 42.5R), limestone Portland cement (CEM II/B-LL 42.5R), and calcium sulfoaluminate cement (SL05 42.5) are analyzed. The latter is known to be low carbon compared to CEM I. Additionally, two conditions, differing in maturity in high or low humidity, at a constant temperature of 20°C, are used to cure the specimens. As a result, mechanical properties, and flexural toughness in particular, strongly depend on the type of cement and on the curing conditions. This is true both for the mortar specimens reinforced with sheep wool fibers and for those reinforced with polypropylene fibers, herein considered as reference fibers.


Document: 

SP355

Date: 

July 1, 2022

Author(s):

Sponsored by: ACI Committees 130, 201, 209, 212

Publication:

Symposium Papers

Volume:

355

Abstract:

The Canada Centre for Mineral and Energy Technology (CANMET) of Natural Resources of Canada, Ottawa, ON, Canada, has played a significant role for more than 40 years in the broad area of concrete technology in Canada. In recent years, CANMET has become increasingly involved in research and development dealing with supplementary cemen¬titious materials, high-performance normalweight and lightweight concretes, and alkali-aggregate reactions. As part of CANMET’s technology transfer program, an international symposium on Advances in Concrete Technology was sponsored jointly with the American Concrete Institute (ACI) and other organizations in Athens, Greece, in May 1992. In June 1995, CANMET, in association with ACI and other organizations in Canada and the United Staes, sponsored the Second CANMET/ACI Symposium on Advances in Concrete Technology in Las Vegas, NV, USA. For the Athens symposium, the CANMET publication “Advances in Concrete Technology,” constituted the proceedings of the symposium. The proceedings from the Las Vegas symposium were published by ACI as SP-154. In August 1997, CANMET, in association with ACI and other organizations in Canada and New Zealand, sponsored the Third CANMET/ACI Symposium on Advances in Concrete Technology in Auckland, New Zealand. The main purpose of the symposium was to bring together representatives from industry, universities, and government agencies to present the latest information on concrete technology, and to explore new areas of research and development. Thirty-three refereed papers from 15 countries were presented and distributed at the symposium. The proceedings were published as ACI SP-171. In June 1998, CANMET, in association with ACI, Japan Concrete Institute (JCI), and several other organizations in Canada and Japan, sponsored the Fourth CANMET/ACI Conference on Recent Advances in Concrete Technology in Tokushima, Japan. More than 80 papers from 20 countries were received and reviewed in accordance with the policies of ACI. Sixty-one refereed papers were accepted for presentation at the conference and for publication as ACI SP-179. In addition to the refereed papers, more than 30 papers were presented and distributed at the conference. In July-August 2001, CANMET, in association with ACI and several organizations in Singapore, sponsored the Fifth CANMET/ACI Conference on Recent Advances in Concrete Technology in Singapore. More than 100 papers from 25 countries were received and reviewed in accordance with the policies of ACI. Forty-six refereed and more than 25 additional papers were accepted for presentation at the conference. The proceedings of the conference were published as ACI SP-200. In June 2003, CANMET, in association with ACI and several organizations in Romania, sponsored the Sixth CANMET/ACI Conference on Recent Advances in Concrete Technology in Bucharest, Romania. More than 40 papers presented at the conference were distributed “as received,” and no formal ACI special publication was published. In May 2004, CANMET, in association with ACI and several other organizations in the United States, sponsored the Seventh CANMET/ACI Conference on Recent Advances in Concrete Technology in Las Vegas, NV. Seventeen refereed papers from more than 10 countries were presented and distributed at the conference. The proceedings of the conference, consisting of the refereed papers, were published as ACI SP-222. In addition to the refereed papers, 20 additional papers were presented and distributed at the conference. In May 2006, CANMET, in association with ACI and several other organizations in Canada and the United States, sponsored the Eighth CANMET/ACI Conference on Recent Advances in Concrete Technology in Montreal, QC, Canada. The proceedings of the conference, consisting of 17 refereed papers, were published as ACI SP-235. In addition to the refereed papers, more than 30 additional papers were presented and distributed at the conference. In May 2007, CANMET, in association with ACI and several other organizations in Canada, Europe, and the United States, sponsored the Ninth CANMET/ACI Conference on Recent Advances in Concrete Technology in Warsaw, Poland. The proceedings of the conference, consisting of 10 refereed papers, were published as ACI SP-243. More than 20 additional papers were presented and distributed at the conference. In October 2009, ACI, in association with several organizations in Canada, Europe and the United States, sponsored the Tenth ACI Conference on Advances in Concrete Technology in Seville, Spain. The proceedings of the conference, consisting of 20 refereed papers, were published as ACI SP-261. In addition to the refereed papers, more than 20 additional papers were presented at the conference and published in a supplementary papers volume. In May 2010, the Committee for the Organization of International Conferences (COIC) (formerly CANMET/ACI Conferences), in association with the Chinese Ceramics Society (CCS) and several other organizations in China, sponsored the Eleventh International Conference on Advances in Concrete Technology and Sustainability Issues in Jinan, China. More than 40 papers were presented at the conference. The proceedings of the conference were published by the CCS, Beijing, China. In October 2012, the COIC, in association with ACI, sponsored the Twelfth International Conference on Advances in Concrete Technology and Sustainability Issues in Prague, Czech Republic. The proceedings of the conference, consisting of more than 30 refereed papers, were published as ACI SP-288. In addition to the refereed papers, more than 40 other papers were presented at the conference and published in a supple¬mentary papers volume. In July 2015, the COIC, in association with ACI, sponsored the Thirteenth International Conference on Advances in Concrete Technology and Sustainability Issues in Ottawa, ON, Canada. The proceedings of the conference, consisting of 28 refereed papers, were published by ACI as SP-303. In addition to the refereed papers, more than 40 other papers were presented at the conference and published in a supplementary papers volume. In October 2018, the CCS and the China Academy of Building Research (CABR), Beijing China, in association with the COIC sponsored the Fourteenth International Conference on Recent Advances in Concrete Technology and Sustainable Issues in Beijing, China. The proceedings of the conference, consisting of 19 refereed papers, were published by ACI as SP-330. In addition to the refereed papers, more than 52 other papers were presented at the conference and published in a supplementary papers volume. In July 2022, after a postponement for the Covid-19 pandemic, the ACI Italy Chapter and the University of Bergamo, Italy, sponsored the Fifteenth International Conference on Recent Advances in Concrete Technology and Sustainable Issues in Milan, Italy. The proceedings of the conference, consisting of 44 refereed papers, were published by ACI as SP-355. In addition to the refereed papers, about 20 other papers were presented at the conference and published in a supplementary papers volume. The main topics of the papers presented at the conference include: the deterioration of concrete structures; the corrosion of metallic reinforcement; the repair techniques of damaged concrete structures by using shrinkage-compensating cement-based mixtures; the protection of concrete structures by special materials to obtain watertight concrete; the reduction of the damage caused by alkali-silica reaction; the use of mineral additions such as fly ash, silica fume, and ground-granulated blast-furnace slag to improve the durability of concrete structures; and the production of concrete by reducing gas emissions and energy consumption such as the use of binders alternative to portland cement (alkali activated materials, geopolymers, sulphoaluminate cement) and recycling of wastes coming from different sources. Thanks are extended to the reviewers for the valuable efforts in reviewing all the manuscripts published in the conference proceedings and in the supplementary volume. The guidance from Dr. V. M. Malhotra and Prof. M. Collepardi, the Honorary Chairpersons of the conference, is sincerely appreciated. Also, acknowledged is the support the American Concrete Institute for the publication of the proceedings (ACI SP-355). The Editors Dr. Denny Coffetti Prof. Luigi Coppola Dr. Terence Holland


Document: 

SP-354_21

Date: 

July 1, 2022

Author(s):

Ricarda Sposito, Matthias Maier, Nancy Beuntner and Karl-Christian Thienel

Publication:

Symposium Papers

Volume:

354

Abstract:

The use of calcined clays as clinker replacement requires the addition of effective superplasticizers. Phyllosilicates in clays are known for their contribution to the pozzolanic reactivity after calcination. Previous investigations on single components of clays identified metaphases of phyllosilicates as the challenging minerals, whereas quartz can promote a proper workability and effectiveness of superplasticizers. It is still under discussion which type of calcined phyllosilicate (1:1 or 2:1), namely metakaolin or metamuscovite/metaillite is more challenging regarding their interaction with superplasticizers. A comparison of these single phyllosilicates among each other and with calcined clays relevant to the cement industry is limited due to physical properties differing too significantly. The study focuses on the question of whether calcined clays with 1:1 or 2:1 phyllosilicates interact better with polycarboxylate ether-based superplasticizers (PCEs) in cementitious systems under the consideration of their physical properties. Five calcined common clays originating from German clay pits are used. The clays differ significantly in their mineralogical composition before calcination, especially regarding their amount of kaolinite, muscovite, and quartz. A Portland limestone cement is replaced by 30% by weight of calcined clay. Two PCEs are used that exhibited good compatibilities with calcined clays in investigations beforehand. Measurements with a rotational viscometer determine the flow resistance each 5, 30, 50, and 105 minutes after water addition. In combination with the adsorption behavior analyzed via zeta potential measurements, the results give fundamental knowledge about the efficiency of superplasticizers depending on the type of calcined clay.


Document: 

SP-355_37

Date: 

July 1, 2022

Author(s):

Mario Collepardi, Silvia Collepardi, Roberto Troli

Publication:

Symposium Papers

Volume:

355

Abstract:

The present paper shows the study of a mixture design of the concrete used in the reinforced foundations of the bridge on the Straits of Messina in Italy. A cube compressive characteristic strength of 35 MPa (5,075 psi) is required for the foundation concrete. Due to the peculiar shape of the concrete foundations (completely embedded in the excavated ground), the damages caused by the thermal stress, the steel corrosion, and the alkali-silica reaction cannot be monitored and repaired. Therefore, a concrete structure must be designed without any damage for at least 200 years due to the very important role of this structure from a social point of view. In order to guarantee this long-term durability, there are two problems to be faced and solved: 1) the heat of cement hydration could cause cracks inside the foundation due to thermal gradients between the hotter nucleus of the massive structure and the colder peripheral areas; 2) the corrosion of the metallic reinforcements caused by the reaction between the metallic iron and the oxygen (O2) present in the air to an extent of about 20%; 3) the alkali-silica reaction causing a local disruption in the concrete. All these problems can be solved using a blast-furnace slag cement such as CEM III B 32.5 R characterized by a very small heat of hydration and adopting a ground coarse aggregate with a maximum size as large as 32 mm (1.28 in): the choice of this aggregate produces a reduction in the amount of mixing water and then of the cement content and reduces the volume of the entrapped air at about 1.3% by concrete volume. This amount of O2 would cause the corrosion of a negligible amount of iron corresponding to only 10 to 13 g (0.4 to 0.5 oz) of steel in 1 m3 (1.31 yd3) of concrete of each foundation. In order to prevent any ingress of air from the environment, the top of the foundation should be protected by self-compacting, self-compressing, and self-curing concrete.


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