Assessment of mechanical and fire resistance for hybrid nano-clay and steel fibres concrete at different curing ages

Abstract

Purpose

Nano-Clay (NC) is reported as a candidate partial replacement for cement, due to its abundance and relatively low cost - beside reported promotion of different concrete properties. On the other hand, Steel Fibres (SF) has proven to have a positive effect on post fire exposure residual strength of concrete. This paper aims to present the outcomes of a comprehensive research program assessing a hybrid mix between NC and SF in concrete mixtures (NCSF-CRETE).

Design/methodology/approach

Physical chemical and physical characterization of NC is performed using different tools as XRF spectrometer, and TEM micrograph. Fresh concrete properties of NSCF-CRETE as slump and air content are investigated. Enhancement in permeability using NSCF is verified by comparing its resistance to the penetration of chlorides resistance with regular concrete mix. Besides, the proposed NCSF-CRETE compressive strength is evaluated compared to mixes with NC and SF each used separately at different curing ages. Besides, NSCF and compared mixes are exposed to an indirect fire testing program – two hours exposure – for: 300, 450 and 600°C. Degradation in compressive strength was investigated after exposure to different temperatures and percentage of residual strength is reported.

Findings

Results indicated an improved performance of NCSF -CRETE of about 40% compared to regular concrete in compressive strength at normal conditions. This improvement extended to its behavior when subjected to indirect fire exposure NSCF also maintained 40% more strength than the residual in regular concrete mix – which suffered severe damage – after 2 h exposure to 600°C.

Originality/value

Using NCSF-Crete allows retrofitting the structure after exposure to such drastic conditions.

Citation

Shalby, O.B., Elkady, H.M., Nasr, E.A.R. and Kohail, M. (2020), "Assessment of mechanical and fire resistance for hybrid nano-clay and steel fibres concrete at different curing ages", Journal of Structural Fire Engineering, Vol. 11 No. 2, pp. 189-203. https://doi.org/10.1108/JSFE-06-2019-0024