Nanoparticles for high performance concrete (HPC) - Nanotechnology in Eco-efficient Construction - page 37

3
Nanoparticles for high performance
concrete (HPC)
F. PACHECO-TORGAL, University of Minho, Portugal,
S. MIRALDO, University of Aveiro, Portugal, Y. DING, Dalian
University of Technology, China and J. A. LABRINCHA,
University of Aveiro & CICECO, Portugal
DOI : 10.1533/9780857098832.1.38
Abstract : According to the 2011 ERMCO statistics, only 11% of the
production of ready-mixed concrete relates to the high performance
concrete (HPC) target. This percentage has remained unchanged since at
least 2001 and appears a strange choice on the part of the construction
industry, as HPC offers several advantages over normal-strength
concrete, specifi cally those of high strength and durability. It allows for
concrete structures requiring less steel reinforcement and offers a longer
serviceable life, both of which are crucial issues in the eco-effi ciency
of construction materials. Despite the growing importance of
nanotechnology, investigations into the incorporation of nanoparticles
into concrete are rare (100 out of 10,000 Scopus concrete-related articles
published in the last decade). It therefore remains to be seen how
research in this area will contribute to concrete eco-effi ciency. This
chapter summarizes the state of current knowledge in the fi eld and
considers the infl uence of nanoparticles on the mechanical properties
of concrete and its durability. It also includes the control of calcium
leaching. The problem of effi cient dispersion of nanoparticles is analyzed.
Key words : Portland cement, nanoparticles, calcium leaching, concrete
durability, high performance concrete (HPC).
￿ ￿ ￿ ￿ ￿ ￿
3.1 Introduction
Concrete is the most widely used of all construction materials. Its produc-
tion currently stands at around 10 km 3 /year (Gartner and Macphee, 2011).
For purposes of comparison, the amount of fi red clay, timber, and steel used
annually is around 2, 1.3 km 3 and 0.1 km 3 , respectively (Flatt et al. , 2012).
Portland cement, which acts as the main binder in concrete, represents
almost 80% of the total CO 2 emissions associated with concrete, which
contribute 6-7% of the planet's total CO 2 emissions (Shi et al. , 2011;
Pacheco-Torgal et al. , 2012). This is of particular concern in the context of
climate change.
The demand for Portland cement is expected to increase by almost 200%
over 2010 levels by 2050, reaching 6,000 million tons per year. According
38