The effects of four typical activators on the early hydration of sintering flue gas desulphurisation ash-steel slag-cement composite cementitious material. (August 2022)

• Record Type: Journal Article
• Authors: Sun, Rui; Wang, Dongmin; Wang, Yiren; Fang, Zhonghua; Zhang, Shuangcheng
• Is Part Of: Cement & concrete composites. Volume 131(2022)
• Publication Date: 2022-08
• Subjects: Sintering flue gas desulphurization ash -- Low carbon -- Tri-isopropanolamine -- Activation -- Hydration mechanism -- Heat release; Composite-reinforced concrete -- Periodicals; Concrete -- Periodicals; Composite materials -- Periodicals; Composites de ciment -- Périodiques; Béton -- Périodiques; Composites -- Périodiques; Béton léger -- Périodiques; Cement composites; Composite materials; Composite-reinforced concrete; Concrete; Lightweight concrete; Periodicals; Electronic journals; 620.135
• DOI: 10.1016/j.cemconcomp.2022.104588
• Languages: English
• ISSNs: 0958-9465

Abstract

Abstract: Millions of tons of steelmaking solid wastes are produced every year worldwide, such as steel slag (SS) and sintering flue gas desulphurisation ash (DA). As using DA directly in building materials is difficult due to its high CaSO3 content, it was combined with SS and ordinary Portland cement (OPC) into desulphurisation ash-steel slag-cement (DASSC) composite cementitious material. The effects of NaOH, Na2 SO4, tri-isopropanolamine (TIPA), and silica fume (SF) on the early hydration of DASSC were investigated based on the workability of fresh pastes, compositions, structures, and properties of hardened pastes. Heat release indicated the hydration of SS and OPC were both inhibited in DASSC, but DA promoted their hydration, increasing the 72 h heat release from 113.62 J/g to 120.84 J/g. TIPA, Na2 SO4, and SF showed improvements of 39.4%, 23.3%, and 14.8% on 14 d compressive strength of DASSC, respectively. TIPA accelerated the hydration of C2 F in SS by complexation to Fe 3+, producing large amounts of C–S–H and C-(A)-S-H, contributing to a decrease in porosity of DASSC from 33.14% to 26.06%, while average pore size decreased from 23.64 nm to 15.98 nm. Highlights: Hydration of SS and OPC were inhibited mutually but DA increased their heat release. Accelerators improved compressive strength of DASSC by TIPA > Na2 SO4 >SF > NaOH. TIPA accelerated the hydration of C2 F by complexation to Fe 3+ with big heat release. TIPA decreased the macropore volume (PD > 150 nm) of DASSC from 45.1% to 10.1%. Efficient activation of DASSC reduced CO2 emissions notably by replacing 50% of OPC.