Shear-thickening behavior of sustainable cement paste — Controlling physical parameters of new sources of supplementary cementitious materials

Abstract

Cement is the main constituent of concrete and the world cement market represents more than 2 billion tons per year. However, the cement industry as a whole is the source of around 8% of global CO2 footprint and therefore any reduction in the cement content can have a significant impact on reducing global CO2 emissions. In terms of sustainability concept, Supplementary Cementitious Materials (SCMs) is one of the most common solutions given its great technical advantages for modern concrete, such as, rheological parameters adjustment, strength gain and full life durability, in addition to economical energy and low environmental impacts. In order to provide updated information for sustainable concrete design and preparation parallel with new sources of SCMs and on the other hand, the relationship between cement paste rheology and flow parameters of concrete. This present study investigates the shear thickening of sustainable cement paste (SCP) under control of some physical parameters of new sources of SCMs such as calcined diatomite (CD), calcined bentonite (CB) and silica fume (SF), respectively. Taking into consideration water-to-binder ratio (w/b) and high-range water-reducer (HRWR) based (PCE and PNS). It was observed that the shear thickening easily occurred when suspensions have a high anhydrous grains concentration, irregular shape, circular shape, high grains sizes (few tens of micrometers) and deflocculated grains state. Regardless of HRWR type and w/b ratios, flow index (n) of SCP substituted by CD is also larger than SCP with CB and SF with unvarying of SCMs level (10%). The intensity sequences of shear thickening of SCP under the influence of SCMs are CD, CB and SF, respectively