scholarly journals Strengthening Behavior of Cemented Paste Backfill Using Alkali-Activated Slag Binders and Bottom Ash Based on the Response Surface Method

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 855
Author(s):  
Qi Sun ◽  
Xueda Wei ◽  
Tianlong Li ◽  
Lu Zhang
Keyword(s):  
Response Surface ◽  
Bottom Ash ◽  
Hydration Product ◽  
Cemented Paste Backfill ◽  
Alkali Activated Slag ◽  
Surface Method ◽  
Optimal Mix ◽  
Paste Backfill ◽  
Activated Slag ◽  
Alkali Activated

A new type of cemented paste backfill (CPB) was prepared by using the bottom ash (BA) from a thermal power plant as an aggregate, alkali-activated slag as a binder, and an air-entraining agent as an admixture. Based on the central composite design (CCD) response surface method, the mix ratio was optimized, and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) was performed on the optimal mix ratio. ImageJ software was utilized to determine the porosity of the experimental samples at various curing ages. The results indicate that the optimal mix ratio of the aggregate-binder ratio is 3.28, the alkali dosage is 3%, the solid content is 67.44%, and the air-entraining agent dosage is 0.1%. As the curing age increases, the porosity of CPB gradually decreases. A calcium aluminosilicate hydrate (C-A-S-H) gel is the main hydration product of alkali-activated slag. At the beginning of the hydration reaction, the slag gradually dissolves, and the C-A-S-H product binds the BA together. At 14 d, complete calcium hydroxide (CH) crystals appeared in the hydration product. Finally, the degree of C-A-S-H crystallization increased further to form a dense structure.

scholarly journals Rheological Properties of Cemented Paste Backfill with Alkali-Activated Slag

Minerals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 288 ◽  
Author(s):  
Yunpeng Kou ◽  
Haiqiang Jiang ◽  
Lei Ren ◽  
Erol Yilmaz ◽  
Yuanhui Li
Keyword(s):  
Yield Stress ◽  
Rheological Behavior ◽  
Plastic Viscosity ◽  
Molar Ratio ◽  
Cemented Paste Backfill ◽  
Lower Yield Stress ◽  
Alkali Activated Slag ◽  
Paste Backfill ◽  
Activated Slag ◽  
Alkali Activated

This study investigates the time-dependent rheological behavior of cemented paste backfill (CPB) that contains alkali-activated slag (AAS) as a binder. Rheological measurements with the controlled shear strain method have been conducted on various AAS-CPB samples with different binder contents, silicate modulus (Ms: SiO2/Na2O molar ratio), fineness of slag and curing temperatures. The Bingham model afforded a good fit to all of the CPB mixtures. The results show that AAS-CPB samples with high binder content demonstrate a more rapid rate of gain in yield stress and plastic viscosity. AAS-CPB also shows better rheological behavior than CPB samples made up of ordinary Portland cement (OPC) at identical binder contents. It is found that increasing Ms yields lower yield stress and plastic viscosity and the rate of gain in these parameters. Increases in the fineness of slag has an adverse effect on rheological behavior of AAS-CPB. The rheological behavior of both OPC- and AAS-CPB samples is also strongly enhanced at higher temperatures. AAS-CPB samples are found to be more sensitive to the variation in curing temperatures than OPC-CPB samples with respect to the rate of gain in yield stress and plastic viscosity. As a result, the findings of this study will contribute to well understand the flow and transport features of fresh CPB mixtures under various conditions and their changes with time.

scholarly journals Alkali-Activated Slag/ Fly Ash Concrete: Mechanism, Properties, Hydration Product and Curing Temperature

2020 ◽  
Vol 9 (9) ◽  
pp. 204-215
Keyword(s):  
Fly Ash ◽  
Hydration Product ◽  
Test Methods ◽  
Curing Temperature ◽  
Environmental Friendliness ◽  
Alkali Activated Slag ◽  
Fly Ash Concrete ◽  
Activated Slag ◽  
Alkali Activated Concrete ◽  
Alkali Activated

Alkali-activated concrete (AAC) is mounting as a feasible alternative to OPC assimilated to reduce greenhouse gas emanated during the production of OPC. Use of pozzolana results in gel over-strengthening and fabricate less quantity of Ca(OH)2 which provide confrontation to concrete against hostile environment. (AAC) is potential due to inheriting the property of disbursing CO2 instantly from the composition. Contrastingly an option to ordinary Portland cement (OPC), keeping this fact in mind the goal to evacuate CO2 emits and beneficiate industrial by-products into building material have been taken into consideration. Production of alkali-activated cement emanates CO2 nearly 50-80% less than OPC. This paper is the general assessment of current report on the fresh and hardened properties of alkali-activated fly ash (AAF), alkali-activated slag (AAS), and alkali activated slag and fly ash (AASF) concrete. In the recent epoch, there has been a progression to blend slag with fly ash to fabricate ambient cured alkali-activated concrete. Along with that the factors like environmental friendliness, advanced studies and investigation are also mandatorily required on the alkali activated slag and fly ash concrete. In this way, the slag to fly ash proportion impacts the essential properties and practical design of AAC. This discusses and reports the issue in an intensive manner in the following sections. This will entail providing a good considerate of the following virtues like workability, compressive strength, tensile strength, durability issues, ambient and elevated-temperature curing of AAC which will improve further investigation to elaborate the correct test methods and to commercialize it.

Sign in / Sign up

Export Citation Format

Share Document