Spray-Dry Agglomerated Nanoparticles in Ordinary Portland Cement Matrix

Abstract

Nano-sized particles have got a focus of great interest for the past decade. These ultrafine particles can have an effect in multiple ways on concrete technology. Although most of the effects of nano-particles are desired, a huge surface area introduced by nanoparticles also incorporates negative effects, such as loss of workability and safety aspects. Agglomeration of nano-sized particles by spray-drying is one potential method to overcome the negative effects. In this study, ultra-fine material was dispersed and agglomerated successfully. Agglomerate structure was analyzed and performance was evaluated with mortar samples. Agglomerated nano-sized material had micron-sized inner porosity, which enabled water penetration into the agglomerates. In water exposure, agglomerates did not dissolve although some of binder glue and dispersing agent leaked out. Wa-ter penetration and organic material leaking enabled high reactivity and workability of the ag-glomerated nanoparticles. In spite of the high reactivity of agglomerated nanoparticles, slightly lower final compression strengths were observed with agglomerated ultrafine particles. The re-sults of this study can be used in concrete technology when further developing admixture tech-nologies and recipe designs. The negative side-effects of the agglomerated nanoparticles can be overcome and accounted for within application areas.