Effect of grinding on early age performance of high volume fly ash ternary blended pastes with CKD & OPC. (1st April 2017)

• Record Type: Journal Article
• Authors: Bondar, Dali; Coakley, Eoin
• Is Part Of: Construction & building materials. Volume 136(2017)
• Page Start: 153
• Page End: 163
• Publication Date: 2017-04-01
• Subjects: CKD -- Intergrinding -- Separate grinding -- Particle size distribution (PSD) -- HVFA ternary pastes; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2017.01.044
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: Grinding beyond one hour is not effective at reducing particle size of HVFA blends. The shortest setting time for HVFA blended pastes occurs for the finest blend. The setting times for activator only ground HVFA pastes are generally shorter. Grinding is largely ineffective at increasing f2d of HVFA pastes but enhances f28d . 2 h is the optimum grinding duration for increasing 28 days strength for HVFA pastes. Abstract: This study investigated setting times and early age compressive strength of the high volume fly ash (HVFA) blended pastes prepared with ground materials. The pastes consisted of 60% Fly Ash + 30% Portland cement (CEM I) + 10% cement kiln dust (CKD) and tests were carried out for four different fly ashes. In phase 1, all the constituent binder materials (class F-fly ash, CEMI and CKD) were initially mixed in the relevant proportions and were ground for varying time periods (1, 2 and 4 h). In phase 2, the CEM I and CKD were mixed and ground for different time periods (1 and 2 h) and then added to the unground fly ash. Both wrapped and submerged curing were used for compressive strength test samples. Overall, grinding of constituents appeared to be largely ineffective at increasing 2 day compressive strength although strength enhancements at 28 days were generally observed. Paste samples that were made from interground constituents generally achieved higher 28 day strengths than corresponding pastes where only the activators were ground, although this was not consistent throughout so further investigation is suggested in this area. Submerged curing is generally less effective in increasing compressive strength than wrapped curing as leaching of CKD is suspected to have occurred.