Page 402 - New Trends in Eco efficient and Recycled Concrete

Application of alkali-activated 13

industrial waste

2
1
2
Jordi Paya ´ , Francisco Agrela , Julia Rosales , Marı´a Martı´n Morales 3
and Marı´a Victoria Borrachero 1
1
Institute of Science and Technology of Concrete (ICITECH), Universitat Polite `cnica de
2
Vale `ncia, Valencia, Spain, Construction Engineering Area, University of Cordoba,
3
Leonardo Da Vinci Building, Rabanales Campus, Cordoba, Spain, Department of
Building Construction, University of Granada, Granada, Spain

13.1 Alkali-activated cement and concrete

Cementitious materials named geopolymers or alkali-activated materials (AAMs)
by Davidovits (1991) have been developed in recent years to decrease the negative
environmental impact of ordinary Portland cement (OPC) production. In this chap-
ter initial concepts about AAMs are explained, such as geopolymer synthesis, the
role of precursors and activators and the performance of these materials.

13.1.1 Necessity to develop low-carbon cement and concrete

OPC has been widely used as traditional binder materials in the construction indus-
try. The annual hydraulic cement produced reached 4.07 billion tonnes in 2013 and
is expected to increase between 4 and 4.5 billion tonnes per year (Schneider et al.,
2011). Above all countries, China, with 1.42 billion, is expected to be the highest
world producer with more than 50% of the global concrete production. Taking into
account that in the manufacture of one tonne of OPC up to one tonne of CO 2 is
emitted (Pacheco-Torgal et al., 2014), the cement industry leads with 6% of the
CO 2 overall emissions (Yusuf et al., 2014).
In the contemporary focus on environmental preservation, the OPC industry is
facing challenges to reduce CO 2 emissions in addition to cost increases and energy
demand, besides raw materials supply in sufficient qualities and quantities
(Schneider et al., 2011).
Therefore, new supplementary cementitious materials (SCMs) have been devel-
oped in order to create new cementitious binders, named geopolymers or AAMs by
Davidovits (1991), which decrease the negative environmental impact of OPC pro-
duction. These new materials are mainly based on different pozzolanic/hydraulic
precursors’ activation by means of commercial alkaline solutions.

New Trends in Eco-efficient and Recycled Concrete. DOI: https://doi.org/10.1016/B978-0-08-102480-5.00013-0
© 2019 Elsevier Ltd. All rights reserved.