International Concrete Abstracts Portal

With the adoption of a policy encouraging the use of recycled aggregates in concrete production, the EU is pursuing the twofold objective of reducing both the demand of natural resources and the environmental impact of the construction industry, that is characterized, as it is well-known, by a significant demand for both energy and raw materials. Therefore, recycling is the main action that can be implemented for turning waste into eco-friendly materials and constituents of newly produced concrete. Particularly, waste concrete can be processed and reused as coarse aggregate, leading to particular kinds of “green concretes” often referred to as Recycled Aggregates Concretes (RACs), in which ordinary coarse aggregates are partially or totally replaced by Recycled Concrete Aggregates (RCAs), while at the same time reducing the so-called Construction and Demolition Waste. However, no well-established theoretical models are capable nowadays of predicting the relevant properties of RACs depending on the actual mixture composition. This paper summarizes the key aspects of a novel physically-based conceptual approach aimed at “designing” RAC mixtures. The formulations proposed in this study are based upon the results achieved from several experimental and numerical investigations carried out for various types of RCAs.

The need to develop greener concrete is increasing day-by-day with the desire to develop sustainable infrastructures, resource conservation, and contribution to the reduction in the causes of global climate change by reducing carbon footprint of concrete and concrete-making materials, through environmentally-friendly techniques of concrete manufacturing by using recyclable materials, for example post-consumer products. This paper describes the possible roles of post-consumer products namely: used tires, plastics, and glass in the manufacture of greener concrete. Extensive research findings from the studies carried out at University of Wisconsin-Milwaukee Center for By-Products Utilization (UWM-CBU) and elsewhere describing the technology for beneficial use of recycled materials obtained from post-consumer materials in the manufacturing of greener concrete has been presented in this paper. The goal is to not waste such materials because waste is wasted if you waste it; otherwise, it is a resource for a society to be beneficially recycled.

The Industrial Revolution in the middle of the 18th century determined mankind’s destiny. The mass production of goods increased the population at an accelerated rate, and, consequently, mankind is facing the risk of natural resources and energy depletion. The greatest challenge to mankind in this century is to ensure the sustainability of the “inhabitants” of the Earth. The basis of mankind’s social and economic activities is infrastructure and buildings. As a result, the construction industry has a far greater influence on the sustainability of mankind and the Earth. Unfortunately, the construction industry has little appreciation of these facts. In order to change from the “old” industry to a “new” industry, the concept of “sustainability” should be introduced as a fundamental idea. The fundamental aspects for considering the sustainability of mankind and the Earth are society, economy, and environment. The essence of the construction industry can be appreciated from these views. There exists interconnection among safety, cost, and environmental impact. In the existing “old” construction engineering, this interconnection is not dealt with systematically. This paper outlines the background on the necessity to introduce a “sustainability” philosophy into the construction sector and proposes a basic framework for sustainability design as a “new” design system

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.

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.