Nanoparticles and recyclable waste in construction materials. From practical necessity to advanced solutions

Abstract

In an increasingly competitive economy, we are facing fierce competition in the construction materials industry, where the use of recyclable waste from demolitions has become more than a necessity. The compensation for the loss of certain properties, which could otherwise lead to a reduction in mechanical characteristics, has been achieved through the addition of nanoparticles with superior qualities. This paper will present the main nanoparticles introduced as subtle additives (ranging from 0.01 percent to a maximum of 1 percent) - currently limited due to manufacturing costs - into the formulations of construction materials such as nanocomposites, nanomortars, nanoconcretes, etc., as well as in sometimes substantial fractions of recycled aggregates, among others. Several types of nanoparticles will be discussed, starting with nanoclay, which improves strength and durability and carbon nanotubes, predominantly used in polymers for construction. In concrete, nano-silica can enhance compressive strength and reduce permeability, graphene oxide can improve mechanical properties and reduce weight and nano-metakaolin, being a pozzolanic material, contributes to long-term strength and durability. At the same time, an analysis will be conducted on some of the recyclable waste from construction, which, under certain conditions, can become integral parts of the formulations for new materials. In this way, we can address two societal issues: the first related to recycling demolition waste and the second to reducing pollution. Furthermore, we can highlight the circular economy, as these materials are reintroduced and repurposed in the creation of new advanced building materials.