Investigation of the effect of consolidation on cement flow behaviour

International audienceOne of the main problems affecting the flow of cement bulk powder is the formation of cohesive arching at the outlet of the hopper, causing blockage of the silo opening and bridge formation. A simple concept is established which outlines these complications. In this context, the interactions of particles lead to a high degree of consolidation of the cement powder and an increase of adhesion force due to the small size and the large surface area of the cement particles. The results from the consolidation test and the flow properties (cohesion) show that the cement powder flow is mainly controlled by internal forces (Van der Waals and adhesion forces) and external forces. These forces have a direct influence on the powder structure, leading to a variable packing behaviour. Since the problem is attributable mainly to interparticle forces, before storage of the cement powder in the silo, the powder should be fluidised with air at a high velocity to disintegrate the cohesive structure and to overcome this undesirable property of cement flow

Mortar with fly ash as a partial cement replacement:Analysing the compressive strength and heat of hydration

Identifying sustainable alternatives and addressing the environmental impacts of cement production are becoming increasingly vital. Alternative materials, such as fly ash, can be used as a partial replacement for cement in concrete and mortar. This study will examine the impact of early-age heat of hydration on compressive strength of mortar when cement is partially replaced by fly ash. The mix proportion used in this study was 1:3 (cement: fine aggregate) with a w/b ratio of 0.4. Furthermore, the replacement of cement with fly ash was calculated based on weight percentage proportions, ranging from 10, 30, and 50% of the cement weight. Fly ash can be effectively used as a substitute for cement to reduce thermal hydration and maintain acceptable levels of compressive strength. As the fly ash substitution rate increased, the thermal hydration of the samples decreased. Nevertheless, the increased strength level may serve as a counterbalance for the initially reduced strength of the mortar that contains fly ash.</p