Mixture design and early age investigations of more sustainable UHPC. (28th February 2018)

• Record Type: Journal Article
• Authors: Abdulkareem, Omar M.; Ben Fraj, Amor; Bouasker, Marwen; Khelidj, Abdelhafid
• Is Part Of: Construction & building materials. Volume 163(2018)
• Page Start: 235
• Page End: 246
• Publication Date: 2018-02-28
• Subjects: Ultra-High Performance Concrete (UHPC) -- Blast Furnace Slag (BFS) -- Sustainability -- Workability -- Setting time -- Hydration -- Compressive strength -- Chemical activation; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2017.12.107
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: The use of a high energy mixer and a results in homogeneous UHPC. Gray Silica Fume improves the compressive strength of UHPC at early age. A low BFS content increases the compressive strength of UHPC at early age. High BFS decreases the compressive strength of UHPC at early age. The presence of KOH improves the early age compressive strength of blended UHPC. Abstract: This paper deals with the possibility to make the Ultra-High Performance Concrete (UHPC) as an environmentally friendly, through cement replacement with Blast Furnace Slag (BFS) and considering its cost and its early age performance. Thereby, a preliminary investigation is carried out, to design an UHPC with local materials and where Silica Fume (SF) is partially replaced with crushed quartz. The results showed that, from a mixture standpoint: i) the use of high energy mixer is necessary to ensure a homogeneous and workable mixture; ii) the polycarboxylate superplasticizer with chemical structure of acrylic polymer (ACP1 ) and saturation dosage of 1.8% gives better workability for UHPC, compared to other six superplasticizers; iii) despite its negative effect on slump flow, Grey Silica Fume (silicium) ensures better compressive strength at early age, than Light one (zirconium). Results showed also that for 30% of cement replacement, the nucleation effect of BFS particles prevails and induces an acceleration of setting and hydration reaction of cement. For BFS contents of 50 and 80%, the dilution effect is dominating, which decelerates the setting and hydration reaction and decreases the peak of heat flow. BFS addition also affects the strength development. At 3 days, the strengths of the blended mixtures of UHPC with 50 and 80% of BFS were decreased by 26 and 66% respectively, while in contrast, there was a slight increase in the strength (+3%) with 30% of BFS compared to the reference mixture (UHPC1 ). For UHPC containing 80% of BFS, the use of chemical activator of potassium hydroxide, with a concentration of [KOH]3, causes slag's dissolution and reaction, which in turn improves the compressive strength by 42% and 11%, at 3 and 7 days, respectively.