Effect of sodium sulfate and nano-SiO2 on hydration and microstructure of cementitious materials containing high volume fly ash under steam curing

Mei, Junpeng; Tan, Hongbo; Li, Hainan; Ma, Baoguo; Liu, Xiaohai; Jiang, Wenbin; Zhang, Ting; Li, Xin

doi:10.1016/j.conbuildmat.2017.12.159

Cited by 66 publications

(24 citation statements)

References 46 publications

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“…In addition, the compressive strength of samples with NaOH as an additional chemical activator after curing for 3 days reached a value of 16.3 MPa (Figure 2). This is because NaOH is a strong alkali, which has an obvious effect on accelerating the early hydration of cement [36]. The hydration rate of the GCM activated by Na 2 CO 3 is also faster, which is due to the fact that Na 2 CO 3 with low incorporation can effectively accelerate the hydration reaction.…”

Section: Resultsmentioning

confidence: 99%

Experimental Studies on Chemical Activation of Cementitious Materials from Smelting Slag of Copper and Nickel Mine

Wang

Wei

et al. 2019

Materials

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Gellable composite materials (GCM) were prepared from a smelting slag of copper and nickel deposits and cement, and activated using gypsum and chemical activators. The effects of material ratio, dosage of chemical activators, and gypsum on the mechanical properties of GCM were studied. Our results showed that the chemical activators of Na2SO4, Na2SiO3, NaOH, and Na2CO3 could improve the compressive strength of the GCM. Considering the market cost and ease operation, the compressive strength of the GCM could be significantly improved with 2% Na2SO4. The experiment results also showed that the compound chemical activator could improve the compressive strength of gelled material. The strength of GCM reaches 41.6 MPa when 2% gypsum and 80% of smelting slags of copper and nickel deposits were used, which met the national standards requirements of GCM. As such, it is expected that a large amount of copper and nickel mining smelting slag could be utilized for the production of cementitious materials.

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Section: Resultsmentioning

confidence: 99%

Experimental Studies on Chemical Activation of Cementitious Materials from Smelting Slag of Copper and Nickel Mine

Wang

Wei

et al. 2019

Materials

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“…The paste with RBP was used in testing the micro properties of cementitious materials. The test of SEM (scanning electron microscope, Hitachi, Tokyo, Japan) was applied to show the micro-structure of cementitious materials, and the elemental map was further presented to quantify the elemental composition of cementitious materials; moreover, the XRD (X-ray diffraction, Bruker AXS, karlsruhe, Germany) test and TG (thermogravimetric, PerkinElmer, Waltham, MA, USA) test were conducted to reveal the effect of RBP incorporation on the hydration products of cementitious materials [37,38]. The mortar and SHCC samples were used to test the mechanical properties, including the compressive strength and flexural strength, and the mechanical test was conducted according to Chinese standard GB50081 (2019) and American standard ASTM-C78 (2005).…”

Section: Micro Properties and Mechanical Properties Determinationmentioning

confidence: 99%

Using Eco-Friendly Recycled Powder from CDW to Prepare Strain Hardening Cementitious Composites (SHCC) and Properties Determination

Wang

et al. 2020

Materials

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Using eco-friendly recycled brick powder (RBP) derived from waste brick to prepare strain hardening cementitious composites (SHCC) provides a new way of recycling the construction and demolition waste (CDW), and the dosage of cement in SHCC can be decreased. This paper investigated the micro-properties and mechanical properties of SHCC containing RBP by a series of experiments. The results showed that RBP had typical characteristics of supplementary cementitious material (SCM). The addition of RBP increased the SiO2 content and decreased the hydration products in cementitious materials; in this case, the mechanical properties of mortar decreased with increasing RBP replacements, and a linear relationship was observed between them. It was noticed that the adverse effect of RBP on the mechanical properties decreased with increasing PVA fiber content in mortar. For SHCC containing various RBP replacements, the ultimate load increased, and the ultimate displacement decreased with increasing curing days. When using RBP to replace cement by weight, the ultimate displacement increased with the addition of RBP. Meanwhile, there was no significant reduction in the ultimate load of SHCC. When using RBP to replace fly ash (FA) by weight, the incorporation of RBP decreased the ultimate displacement of SHCC, whereas the ultimate load was improved. For example, the ultimate load and displacement of SHCC with 54%RBP were 17.6% higher and 16.4% lower, respectively, than those of SHCC with 54% FA.

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“…Zhang reported that cement mortar modified with nanosilica (NS) and silica fume could be used as SPM to enhance the impermeability [22]. e reason was revealed that NS and silica fume not only consumed CH to form the dense C-S-H but also exerted the excellent filling effect, thereby declining the porosity, increasing density, improving the microstructure including interfacial transition zone (ITZ), and enhancing the mechanical performance [23][24][25][26]. Additionally, the inorganic materials generally performed better antiaging property and also showed excellent ability to augment the impermeability by coating on the surface [27,28].…”

Section: Introductionmentioning

confidence: 99%

Effect of Nanosilica on Impermeability of Cement-Fly Ash System

Liu

Zhang

Tong

et al. 2020

Advances in Civil Engineering

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Surface protection has been accepted as an effective way to improve the durability of concrete. In this study, nanosilica (NS) was used to improve the impermeability of cement-fly ash system and this kind of material was expected to be applied as surface protection material (SPM) for concrete. Binders composed of 70% cement and 30% fly ash (FA) were designed and nanosilica (NS, 0–4% of the binder) was added. Pore structure of the paste samples was evaluated by MIP and the fractal dimension of the pore structure was also discussed. Hydrates were investigated by XRD, SEM, and TG; the microstructure of hydrates was analyzed with SEM-EDS. The results showed that in the C-FA-NS system, NS accelerated the whole hydration of the cement-FA system. Cement hydration was accelerated by adding NS, and probably, the pozzolanic reaction of FA was slightly hastened because NS not only consumed calcium hydroxide by the pozzolanic reaction to induce the cement hydration but also acted as nucleation seed to induce the formation of C-S-H gel. NS obviously refined the pore structure, increased the complexity of the pore structure, and improved the microstructure, thereby significantly improving the impermeability of the cement-FA system. This kind of materials would be expected to be used as SPM; the interface performance between SPM and matrix, such as shrinkage and bond strength, and how to cast it onto the surface of matrix should be carefully considered.

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Effect of sodium sulfate and nano-SiO2 on hydration and microstructure of cementitious materials containing high volume fly ash under steam curing

Cited by 66 publications

References 46 publications

Experimental Studies on Chemical Activation of Cementitious Materials from Smelting Slag of Copper and Nickel Mine

Experimental Studies on Chemical Activation of Cementitious Materials from Smelting Slag of Copper and Nickel Mine

Using Eco-Friendly Recycled Powder from CDW to Prepare Strain Hardening Cementitious Composites (SHCC) and Properties Determination

Effect of Nanosilica on Impermeability of Cement-Fly Ash System

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