Development of Colloidal Nanosilver as a High-Workability Nanoadditive for Cement Composites: A Mechanistic Approach

Abstract

The adverse effects on flow and higher replacement dosage are key constraints limiting the large-scale application of nanomaterials in concrete. With a view to addressing the above limitation, the present study discusses the development of colloidal nanosilver (cAgNPs). The Lablab purpureus (L.) pod-based green synthesis adopted enriches cAgNPs with phytochemicals, which synergistically improves the flowability of cement concrete. The contact angle and surface tension measurements confirm its flow affinity. The relative improvement in the performance of designed cAgNPs against commercial nanosilica (SiNPs) was assessed in terms of flow and strength measurements in cement paste specimens. In comparison to SiNPs, inclusion of cAgNPs enhances flow by 80%, while it decreases the superplasticizer requirement by 150%. The compressive strength of both is found to be comparable, while the reactivity as confirmed through TGA and FT-IR is found to be dependent on the binder system. The relative improvement in binding ability with inclusion of cAgNPs is confirmed through FE-SEM and EDS analysis. The above performance improvements are obtained for optimal replacement dosages of 1% and 0.5%, respectively, for cement and blended paste, thus enhancing its economic viability. The ability of cAgNPs to enhance flowability through improved consistency and reduced water demand without compromising strength is a critical departure from conventional nanoparticles and can potentially enhance largescale applications in concrete.