Use of Supplementary Cementitous Material in Concrete Effect on Fresh Concrete Properties

Abstract

Minimizing the use of clinker content by using supplementary cementitious materi als (SCMs) requires consideration of their influence on the fresh state properties as well as long-term strength and durability. This study investigated six different SCMs, both natural and industrial, i.e. ground granulated blast furnace slag (GGBS), fly ash (FA), calcined (Nova) clay, volcanic pozzolan from Iceland (VPI), pumice (Yalite) from Grekland and Boliden material (SCMentum) and compared their performance with CEM I 52.5R cement. Mortars containing 40% of SCM were analyzed in terms of water demand, workability, workability loss over 2 hours, bleeding, segregation, setting time, and hydration behavior. One-day strength was additionally determined replacing 20%, 40% and 60% of the cement. The standard test method was used such as mor tar flow test using Hagermann cone for workability, Ultrasonic testing for setting time, calorimetry test for hydration behavior, compressive strength test according to EN-196 1. The results illustrated that the type of SCMs considerably influences the balance be tween flowabiliy and stability. Fly Ash demonstrated the highest flow and bleeding, while Nova Clay resulted in the lowest flow, but experienced the greatest workability loss, around 53% in two hours. VPI showed the most balanced overall performance in cluding the highest one day strength. The initial setting time ranged from three to four hours, where Fly Ash and VPI started setting in 3 hours, and GGBS and Pumice started in 4 hours. All six SCMs exhibited lower early strength than the reference cement and strength decreased more with increasing SCM. In general, the results demonstrated that it is necessary to consider the fresh state properties and early strength when evaluating the suitability of SCM.