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International Concrete Abstracts Portal

Showing 1-5 of 49 Abstracts search results

Document: 

SP305-24

Date: 

September 1, 2015

Author(s):

Yuanyuan Wan and Yonghao Fang

Publication:

Symposium Papers

Volume:

305

Abstract:

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.

DOI:

10.14359/51688584


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:

Symposium Papers

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.

DOI:

10.14359/51688604


Document: 

SP305-01

Date: 

September 1, 2015

Author(s):

Maurizio Acito; Fabio Cavagnera; Claudio Chesi; Vito Lavermicocca; Valentina Sumini

Publication:

Symposium Papers

Volume:

305

Abstract:

In relation to reinforced concrete high-rise buildings built in the Fifties and Sixties of the 20th Century, it has acquired importance, in the last few years, the analysis of the capabilities to withstand various kinds of environmental risks, defined according to actual parameters. The provisions prescribed by new structural design codes practiced today, indeed, have substantially changed both design actions and verification procedures as well, if compared to the building criteria in use in the past. This kind of analysis gives evidence to specific design performances which are seen as prevalent nowadays but were not considered in older versions of the codes, as the earthquake loads. In the present work this problem is discussed with reference to the case study offered by the Milan Municipality 25 story r.c. building erected in Milano in the ‘60s. Typically, this kind of buildings were designed for the effect of vertical loads and wind lateral loads only. At present, after being recognized of strategic importance for the society, they have to be verified also for the seismic resistance. Although the seismic hazard is classified as low in the area of Milano, design seismic forces are a little more severe than wind actions for this building, due to the limited ductility resources available in the structural elements, mainly in the shear walls. Consequently, the value which can be assigned to the load reduction factor is extremely low.

DOI:

10.14359/51688561


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.

DOI:

10.14359/51688583


Document: 

SP305-31

Date: 

September 1, 2015

Author(s):

Bartolomeo Coppola; Luciano Di Maio; Luc Courard; Paola Scarfato and Loredana Incarnato

Publication:

Symposium Papers

Volume:

305

Abstract:

In recent years the increasing interest for eco-sustainable building materials and the rising issue of plastic waste disposal are leading to the engineering of new composite construction materials incorporating post-consumer recycled plastics, able at the same time to meet new standard requirements, in terms of energy efficiency, and to reduce the consumption of natural resources. In the context of these issues, we have performed investigations on the effects of the addition of foamed artificial aggregates deriving from recycled plastic materials to a cementitious mortar. For this purpose, several mortar samples containing natural sand and different amounts (10, 25 and 50 % by volume) of foamed recycled plastic wastes were produced. The foaming of the recycled plastic waste was performed in laboratory by a foam extrusion process using a blowing agent (2 wt.%). An artificial aggregates particle size distribution similar to standard sand was used. Rheological and physical properties of lightweight mortar were studied. The improved surface roughness of foamed plastic aggregates ensures a more continuous interface and the presence of surface pores provides interlocking effect with cement paste. Replacement of natural sand by artificial aggregates produces a lightweight mortar but reduces mechanical properties.

DOI:

10.14359/51688591


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