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.

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.

Simply-supported one-way R/C slabs are commonly used in the covers of small and medium underground facilities, where durability is the main issue face with rather limited service loads and short spans (2-4 m [6.5-13.0 ft]). The structural performance, however, should not be underrated, as being the slab in a roundabout does not prevent a heavy truck from straying off the right lane! To have fresh information on durability and cracking (working loads), and on the bearing capacity and failure mode (ultimate loads), displacement-controlled tests have been recently performed in Milan on four typical rectangular R/C slabs suspended along their short sides via corbels (dapped ends; size: 1.3x2.2x0.15 m [51x87x6 in.]). A transversely-distributed or concentrated load was applied either at mid-span (in the bending tests), or at 1/10 of the span (in the shear tests). The two slabs Type A are provided with longitudinal bent-up bars in the main body and hooks in the corbels. On the contrary, the slabs type B are reinforced via two continuous layers of longitudinal straight bars. Under the working loads, cracking never occurred, neither in bending nor in shear – to the advantage of durability – while above the working loads rather complex crack patterns formed in the D zones close to the corbels, particularly under the concentrated load, which brought in 3-D effects, with a limited reduction in the bearing capacity. Refining the reinforcement layout is shown – once more - to markedly improve slab performance, with little or no extra cost.

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.

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.