Objectives

The modification of cement-based materials with carbon-based nano-inclusions will lead to the development of innovative products possessing multi-functionality and smartness. The groundbreaking and innovative scientific achievements of the proposed work cover broad spectrum accomplishments in basic and applied research, as well as in the development of new products.

A structure is considered smart when it is made from a material that, among other things, has certain desirable properties (multi-functionality). Such properties, when monitored non-destructively, can provide information regarding the integrity during the lifetime of a structure (smart). The real-time monitoring of the multifunctional characteristics of the material enables the prediction of the level of damage and/or the potential failure of the structure. Smart cement-based structures should be therefore made out of modified concrete with properties different than those of the conventional concrete. The conventional concrete is not electrically conductive; its heat capacity is high, while its thermal insulation property is low. In addition, its flexural strength and toughness are low, therefore requiring steel reinforcement in large quantities for using it in structural applications. Target properties of a cement-based multifunctional material should be: exceptional mechanical properties which would enable a highly resistant lightweight structure, electrical and thermal conductivity, and piezo-electric characteristics.

The basic idea in the proposed work is hence: (a) to modify the cement paste appropriately in order to produce modified concrete with the aforementioned desirable properties (multi-functionality); (b) to monitor, in real-time, the degradation of the structural integrity of the material using the multi-functional characteristics as indicators/sensors (smart material).

The main objective of the proposed work is to develop innovative products (nano-modified cement, plasticizer and concrete) which will be used in multi-functional, smart structural elements. Conventional materials (cement, plasticizer, concrete) will be appropriately modified with carbon-based nanoscale fibers (carbon nanotubes-CNTs, carbon nanofibers-CNFs, and chopped carbon fibres-CF), in order to achieve multi-functional properties. Next objective is to determine and verify the different functionalities of the nano-modified materials by studying the mechanical behavior as well as by monitoring in real time their structural integrity in simulated operational (mechanical and/or environmental) conditions, using the intrinsic multi-functional properties of the material as damage sensors. In order to demonstrate the possibility of integrating the new nano-modified materials into practice for full-scale application in concrete, the effect of the nano-reinforcement on the performance and the multi-functionality of nano-modified lab scale material as well as of structural components will be assessed by means of advanced electrical, thermal, acoustic and optical non-destructive techniques.

Finally, the cost effectiveness of the new products will be fully assessed to estimate (a) the optimum amount and type of nanoreinforcement to meet both cost and strength needs, (b) the cost of unmodified vs. nanomodified materials, and (c) the weight and cost reduction of the modified nanocomposites as well as the reduction in steel quantity due to the addition of the nanoreinforcement, so that an optimized manufacturing process for the modified materials based on mechanical and cost analysis can be proposed.