Papers

Surface treatments of recycled aggregates for the preparation of an all-waste based concrete

J. Branquinho1, Agnese Attanasio2, Alessandro Largo 2, Paulo Ramos1, Dora Coelho 1

1CeNTI – Centre for Nanotechnology and Smart Materials, Rua Fernando Mesquita, 2785, 4760-085 Vila Nova de Famalicão, Portugal

2CETMA - Engineering, Design & Materials Technologies Centre, s.s. 7 Appia Km 706+030, c/o Cittadella della Ricerca - 72100 Brindisi – ITALY
 

Abstract (150 words)

Energy consumption and CO2 emission on the construction sector has been a major concern worldwide, leading to the development of new and more energy and environmental friendly technologies. This project aims the development of new technology routes to integrate waste materials in the production cycle of concrete, resulting in an innovative light-weight, eco-compatible, energy efficient and cost-effective construction material.

The presented work focused on the development of physic-chemical superficial treatments to properly calibrate the hygroscopicity (water absorption) of recycled foamed aggregates, as well as to improve their adhesion to the binder paste. Water absorption is an important parameter in the mix-design and it influences the characteristics of concrete in the fresh and hardened state. Also, the adhesion between the aggregates and the cement-matrix is a significant issue, since it affects the mechanical behavior of the resulting concrete. In both cases, performed superficial treatments were properly evaluated and showed promising results.

-          R&D Polymers Team Leader at CeNTI since 2012

-          Researcher at CeNTI since 2009

-          McS Biochemical Engineering

-          Degree in Chemistry – Organic Chemistry

-          Main areas of interest – Polymers, materials chemistry, nanotechnology

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Designing sustainable concrete on the basis of equivalence performance: assessment criteria for safety

Visser, J.H.M., Bigaj-van Vliet, A. J.
Department of Structural Reliability, TNO, Postbox 49, 2600 AA Delft, The Netherlands
 

Abstract

In order not to hamper innovations, the Dutch National Building Regulations (NBR) allow an alternative approval route for new building materials. It is based on the principles of equivalent performance which states that if the solution proposed can be proven to have the same level of safety, protection of health, energy efficiency and protection of the environment, it is accepted as well.

The framework of equivalence performance has been worked out in this paper with respect to safety. Three types of assessment criteria have been derived: for individual vales, for characteristic values and for relationships. More than one assessment criteria can apply at the same time. An example for a new material containing 50 % of recycled concrete and 50 % of recycled sand-lime brick aggregates illustrates the consequence of the assessment for two properties: compressive strength and tensile strength.

The assessment procedure provides a new route for fast incorporation of new concrete-like materials in construction without compromising the safety of the structures. This will not only stimulate innovations. Since it is expected to be applicable for many newly developed green materials, it also makes a significant contribution to reduction in CO2 and energy consumption as well as raw materials in a relatively short time. 

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Study on the suitability of volcanic amorphous aluminosilicate rocks (perlite) for the synthesis of geopolymer- based concrete

M. Taxiarchou, D. Panias, Ch. Panagiotopoulou, A. Karalis, C. Dedeloudis

Abstract

Geopolymerisation is a low cost, low energy demanding, green technology that can transform a variety of silicate and aluminosilicate raw materials and industrial by- products to useful, high added value products. Due to their excellent mechanical properties, the application of geopolymeric materials for the replacement of traditional construction materials is gaining ground. The most commonly used raw materials for geopolymer synthesis include metakaolin, fly ash, Ground Granulated Blast Furnace Slag (GGBFS) and their mixtures. In this work, an amorphous aluminosilicate rock (perlite) was selected as raw material, in order to determine its ability to synthesize new Portland cementless binders for concrete. The effect of the following synthesis parameters on the development of the mechanical properties of the geopolymeric formulations were studied:

  • The curing conditions (t 24, 48, 72h , T 50, 70, 90 °C)
  • The water/ solid mass ratio ( mw/ms 0.28-0.37)
  • Si/Al molar ratio= 5.6-6.5
  • The alkali content and type of alkali ion (R/Al molar ratio 0.65-1.05 R: Na or K)

The structural changes were identified by means of XRD, FTIR and SEM while the mechanical properties were evaluated through compressive strength measurements. The most promising formulations were used for the synthesis of mortars using standard silica sand, according to ASTM C109/109C. Also in this case, compressive strength measurements were carried out,
while the structure was observed with XRD, FTIR and SEM. The present study showed that perlite is a promising raw material for geopolymer synthesis resulting in geopolymeric pastes with compressive strength higher than 30 MPa. In contrast to the other raw materials currently used for geopolymerisation, the geopolymerisation of perlite requires prolonged curing time of a total duration of 5 days at 70 °C.

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