Alkali-activated pastes by Basic Oxygen Furnace slag and fly ash: Mechanical and microstructural analysis

IF 6.5 2区 工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY
Heloina Nogueira da Costa , Antônio Eduardo Bezerra Cabral , Ricardo Emílio Ferreira Quevedo Nogueira
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Abstract

This study aims to investigate the mechanical behavior and microstructure formation of alkali-activated pastes prepared from basic oxygen furnace (BOF) steel slag and fly ash (FA). In addition, the fluidity and setting time of five different proportions of FA and BOF (0/100, 75/25, 50/50, 25/75 and 100/0) were prepared using silicate and sodium hydroxide as activators. Compressive strength (1, 7 and 28 days), stress-strain curve, modulus of elasticity and fracture energy were evaluated in the hardened state. Infrared spectroscopy, scanning electron microscopy, X-ray diffraction and thermal analysis were used to analyze the microstructure. The best mini-slump results was 50/50 paste with 117.3 mm, 8.0 Pa and 2096.8 kg/m3 of spreading diameter, yield stress and density, respectively. The calcium present in BOF accelerated the setting time. Compressive strength of paste 50/50 presented higher, 52.3, 57.6 and 62.3 MPa at 1, 7 and 28 days and also the higher modulus of elasticity (25.9 GPa) and fracture energy (116.9 N/m). Microstructural analyses indicate the increasing the BOF slag content, increases the availability of calcium, densifying the microstructure, due to the formation of C-(N)-A-S-H (hydrated calcium aluminosilicate) and C-A-S-H (hydrated calcium aluminosilicate) gels, which are also responsible for the mechanical strength growth up to 50 % BOF increment. However, in pastes with higher fly ash contents (75/25 and 100/0), the N-A-S-H (hydrated sodium aluminosilicate) gel type predominates. Therefore, the results obtained confirm the potential of using BOF slag as a calcium and Fa as a silica source in alkali-activated pastes.
碱性氧炉炉渣和粉煤灰碱活化膏体:力学和显微结构分析
研究了以碱性氧炉(BOF)钢渣和粉煤灰(FA)为原料制备的碱活性膏体的力学行为和微观结构形成。此外,以硅酸盐和氢氧化钠为活化剂,制备了FA和BOF 5种不同配比(0/100、75/25、50/50、25/75和100/0)的流动性和凝固时间。对硬化状态下的抗压强度(1、7和28天)、应力-应变曲线、弹性模量和断裂能进行了评价。采用红外光谱、扫描电镜、x射线衍射和热分析等方法对其微观结构进行了分析。最小坍落度为50/50,铺展直径、屈服应力和密度分别为117.3 mm、8.0 Pa和2096.8 kg/m3。转炉中钙的存在加快了凝固时间。1、7、28 d时,膏体抗压强度分别为52.3、57.6、62.3 MPa,弹性模量(25.9 GPa)和断裂能(116.9 N/m)较高。微观结构分析表明,随着转炉炉渣含量的增加,钙的可用性增加,微观结构致密化,这是由于C-(N) a - s - h(水合铝硅酸钙)和C- a - s - h(水合铝硅酸钙)凝胶的形成,这也是机械强度增长高达50% %转炉增加量的原因。而在粉煤灰含量较高的膏体中(75/25和100/0),N-A-S-H(水合铝硅酸钠)凝胶型占主导地位。因此,研究结果证实了转炉炉渣作为钙源和Fa作为硅源用于碱活性膏体的潜力。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
CiteScore
7.60
自引率
19.40%
发文量
842
审稿时长
63 days
期刊介绍: Case Studies in Construction Materials provides a forum for the rapid publication of short, structured Case Studies on construction materials. In addition, the journal also publishes related Short Communications, Full length research article and Comprehensive review papers (by invitation). The journal will provide an essential compendium of case studies for practicing engineers, designers, researchers and other practitioners who are interested in all aspects construction materials. The journal will publish new and novel case studies, but will also provide a forum for the publication of high quality descriptions of classic construction material problems and solutions.
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