Rheological control of cement paste for applying prepackaged ECCs (Engineered Cementitious Composites) to self-consolidating and shotcreting processes

Abstract

Prepackaged ECCs are rheologically designed by determining the amount of admixtures such that they are suitable for self-consolidating and shotcreting processes. Rheology is controlled such that it can be directly applicable to construction in the field, using prepackaged products with all powdered ingredients. To control the rheological properties of the composites, which have different fluid properties that facilitate two types of processing (i.e., self-consolidating and shotcreting processes), the viscosity change of the cement paste suspensions over time was initially investigated. The proper dosage of the admixtures in the cement paste was then determined. The two most appropriate mixture proportions were then selected by conducting self-consolidating and shotcreting tests. A series of self-consolidating and shotcreting tests demonstrated excellent self-consolidation properties and sprayability of the prepackaged ECC. Subsequent direct tensile tests also revealed hardened properties of prepackaged ECC comparable to those of normally cast ECC.