Concrete is the most versatile construction material. However, the image of concrete looks often one of something non-friendly from an environmental point of view. Further developments, “green chemistry” and new techniques, should continue to be introduced into the cement and concrete industry. This will provide distinct alternatives to OPC dominating inside cement market. Simultaneously new scientific and technological breakthroughs are required. One of such additional strategies is based on advanced concrete technology concepts, which enables the reduction of the quantity of cement used in concrete, by combining fillers and various admixtures. Another strategy is based on a new design of the structural component, to evaluate the use of different materials and to achieve an overall reduction of the environmental impacts. This strategy highlights Life Cycle Analysis and Design, Performance Standards for Durability, Environmentally Driven Design and the role of the reinforcement, because the conventional steel reinforcement contributes to environmental footprint as much as the cement in the concrete. Composite materials, including polymer composite reinforcement, non-metallic fibers and the external reinforcement for repair and strengthening, would be widely used in modern construction. Additional benefits of synergy between these different solutions might be realized leading to reduction of more than 50% of environmental load.

Estimation of energy and material input-output during the production and other lifecycle stages is the most basic and repeated procedure to evaluate the environmental impact. Therefore, it is important to develop an accurate, convincing and field-verified model for estimating the material and energy input-output at each lifecycle stages and at each plant or site. With this background, we have been developing energy-use estimation model at concrete production stage. In this paper, we firstly present the unique characteristics of concrete production process in Japan based on our previously proposed model. With this model, we statistically estimate three factors through the field questionnaire survey on ready-mixed concrete plants. The estimation has shown the following characteristics in electric consumption; 1) major manufacturing machineries such as mixer, belt conveyer and blowers are less electric consuming than facilities in constant operation (ex. air compressor), 2) around half of the constant electric consuming facilities can be stopped (at least in some conditions) when concrete shipping is not in queue, which may imply possible options for the reduction of electric energy-use.

The construction industry is accountable for about 50 percent of the global resource consumption. Within this, traditional concrete is one of the products with a manufacturing process that has a relatively large impact on the environment. As a result of the rising awareness regarding sustainability, concrete suppliers, product manufacturers, and building contractors are concerned about which environmental impact their product has. Based on a life cycle assessment (LCA) it is possible to analyze the different stages in the life cycle of structures and to evaluate the respective impacts. Such a study is presented here for a producer of high-strength concrete building materials, applying a cradle-to-gate approach with options. Specific company data were combined with general input from databases, and a functional unit of 1m^³ was adopted to be able to compare the different results. Based on this, it was determined that whereas the reinforcing and prestressing steel and the cement dominate the impact contributions, other factors such as transport by road, maintenance, aggregates, fabrication and concrete waste production during fabrication are non-negligible. A further impact study shows that several adaptions can potentially reduce the impact on the environment with 20 to 30 percent, depending on the assessment method used.

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.

Diffusion and migration are the two major transport ways of chloride ions in concrete. The single-species models were usually used to predict the chloride diffusion and migration behavior. However, the diffusion and migration processes of chloride ions in concrete are more complicated than expected. The single-species models have obvious limitations in predicting the diffusion and migration processes. In this paper, two multi ionic models are introduced to predict the chloride diffusion and migration processes, respectively. In the diffusion model, the ionic actions and multi-phase reactions are both considered in order to simulate the realistic situations. In the migration model, the ionic actions are also considered while the multi-phase reactions are ignored due to the strong electrical field force applied in the migration test. Besides, a pore structure hypothesis is assumed by a simple deduction to distinguish the migration process from the diffusion process. By considering the factors mentioned above, the governing equations of diffusion and migration models are deduced respectively. In order to verify the multi ionic models, two numerical examples and the verification tests are also conducted. The results show that the multi-ionic models are feasible to predict the chloride diffusion and migration in concrete.