Study on the drying shrinkage of alkali-activated coal gangue-slag mortar and its mechanisms

2019 ◽  
Vol 225 ◽  
pp. 204-213 ◽  
Author(s):  
Ma Hongqiang ◽  
Chen Hongyu ◽  
Zhu Hongguang ◽  
Shi yangyang ◽  
Ni Yadong ◽  
...  
Keyword(s):  
Drying Shrinkage ◽  
Coal Gangue ◽  
Activated Coal ◽  
Activated Coal Gangue ◽  
Alkali Activated

scholarly journals Effects of Expansive Additives on the Shrinkage Behavior of Coal Gangue Based Alkali Activated Materials

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 816
Author(s):  
Xu Gao ◽  
Chao Liu ◽  
Zhonghe Shui ◽  
Rui Yu
Keyword(s):  
Mechanical Properties ◽  
High Performance Concrete ◽  
Early Stage ◽  
Drying Shrinkage ◽  
Coal Gangue ◽  
Reaction Process ◽  
Activated Coal ◽  
Activated Coal Gangue ◽  
Alkali Activated ◽  
Shrinkage Behavior

The suitability of applying shrinkage reducing additives in alkali activated coal gangue-slag composites is discussed in this study. The effect of sulphoaluminate cement (SAC), high performance concrete expansion agent (HCSA) and U-type expansion agent (UEA) on the reaction process, shrinkage behavior, phase composition, microstructure and mechanical properties are evaluated. The results show that the addition of SAC slightly mitigates the early stage reaction process, while HCSA and UEA can either accelerate or inhibit the reaction depending on their dosage. The addition of SAC presents an ideal balance between drying shrinkage reduction and strength increment. As for HCSA and UEA, the shrinkage and mechanical properties are sensitive to their replacement level; excessive dosage would result in remarkable strength reduction and expansion. The specific surface area and average pore size of the hardened matrix are found to be closely related with shrinkage behavior. SAC addition introduces additional hydrotalcite phases within the reaction products, while HCSA and UEA mainly result in the formation of CaCO3 and Ca(OH)2. It is concluded that applying expansive additives can be an effective approach in reducing the drying shrinkage of alkali activated coal gangue-slag mixtures, while their type and dosage must be carefully handled.

Shrinkage-reducing measures and mechanisms analysis for alkali-activated coal gangue-slag mortar at room temperature

2020 ◽  
Vol 252 ◽  
pp. 119001 ◽  
Author(s):  
Hongqiang Ma ◽  
Hongguang Zhu ◽  
Hongyu Chen ◽  
Yadong Ni ◽  
Xiaonan Xu ◽  
...  
Keyword(s):  
Room Temperature ◽  
Coal Gangue ◽  
Activated Coal ◽  
Activated Coal Gangue ◽  
Alkali Activated

Study on compressive strength and durability of alkali-activated coal gangue-slag concrete and its mechanism

2020 ◽  
Vol 368 ◽  
pp. 112-124 ◽  
Author(s):  
Hongqiang Ma ◽  
Hongguang Zhu ◽  
Chao Wu ◽  
Hongyu Chen ◽  
Jianwei Sun ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Coal Gangue ◽  
Activated Coal ◽  
Strength And Durability ◽  
Activated Coal Gangue ◽  
Alkali Activated

Immobilization of uranium soils with alkali-activated coal gangue–based geopolymer

2021 ◽  
Author(s):  
Shukui Zhou ◽  
Jiali Li ◽  
Lishan Rong ◽  
Jiang Xiao ◽  
Yingjiu Liu ◽  
...  
Keyword(s):  
Coal Gangue ◽  
Activated Coal ◽  
Activated Coal Gangue ◽  
Alkali Activated

scholarly journals Study of Mechanical Properties and Durability of Alkali-Activated Coal Gangue-Slag Concrete

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5576
Author(s):  
Hongguang Zhu ◽  
Sen Yang ◽  
Weijian Li ◽  
Zonghui Li ◽  
Jingchong Fan ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Damage Mechanics ◽  
Ordinary Portland Cement ◽  
Coal Gangue ◽  
Function Model ◽  
Freeze Thaw ◽  
Activated Coal ◽  
Activated Coal Gangue ◽  
Alkali Activated

Herein, a new geopolymer is recognized as a potential alternative cementing material of ordinary Portland cement (OPC), which is used for reducing carbon emissions and efficiently recycling the waste. Therefore this paper mainly studied the alkali-activated coal gangue-slag concrete (ACSC) was prepared by using the coal gangue-slag and Na2SiO3 and NaOH complex activator. The ratio of coal gangue (calcined and uncalcined) coarse aggregate replacing the gravel was 0%, 30%, 50%, 70%, and 100%. The water and salt freeze-thaw resistance, compressive strength, chloride permeation, microstructure, performance mechanism, inner freeze-thaw damage distribution, and mechanics models of ACSC were investigated. Results show that ACSC displayed excellent early age compressive strength, and the compact degree and uniformity of structure were better compared with the ordinary Portland cement (OPC) when the coal gangue replacement rate was less than 50%. The ACSC demonstrated the best chloride penetration resistance under 30% uncalcined coal gangue content, which was less than 27.75% lower than that of using OPC. At the same number cycles, especially in the salt freezing, the calcined coal gangue had lowered advantages of improving resistance freeze-thaw damage resistance. Water and salt accumulative freeze-thaw damage mechanics models of ACSC were established by using the relative dynamic elasticity modulus. The exponential function model was superior to the power function model with better precision and relativity, and the models accurately reflected the freeze-thaw damage effect.

scholarly journals Preparation and Reaction Mechanism Characterization of Alkali-activated Coal Gangue–Slag Materials

Materials ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2250 ◽  
Author(s):  
Hongqiang Ma ◽  
Hongguang Zhu ◽  
Cheng Yi ◽  
Jingchong Fan ◽  
Hongyu Chen ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Sodium Hydroxide ◽  
Energy Dispersive Spectrometer ◽  
Coal Gangue ◽  
Influential Factor ◽  
Raw Material ◽  
Activated Coal ◽  
Activated Coal Gangue ◽  
Alkali Activated ◽  
Slag Content

In this paper, slag is used as a calcium source to make alkali-activated coal gangue–slag (AACGS) based material. The reaction mechanism of AACGS materials was discussed in depth by means of XRD, FT-IR, 29Si MAS-NMR (nuclear magnetic resonance) and SEM-EDS (energy dispersive spectrometer). The experimental results show that coal gangue can be used as a raw material for preparing alkali-activated materials. The liquid–solid ratio is the most influential factor on AACGS paste fluidity and strength, followed by slag content. As the modulus of sodium hydroxide increases, the depolymerization process of the reactant precursor is accelerated, but the high sodium hydroxide concentration inhibits the occurrence of the early coal gangue–slag polycondensation reaction, and exerts little effect on the 28 d compressive strength. Ca2+ in the slag promotes exchange with Na+, and the product is converted from N-A-S-H gel to C-(A)-S-H gel, and C-(A)-S-H is formed with higher Ca/Si ratio with the increase of slag content. The slight replacement of coal gangue by slag can greatly improve the reaction process and the strength of AACGS materials.

scholarly journals Experimental Study of the Mechanical and Microstructure Characteristics of Coal Gangue Road Stabilization Materials Based on Alkali Slag Cementation

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3601
Author(s):  
Changbai Wang ◽  
Junxin Yang ◽  
Shuzhan Xu
Keyword(s):  
Compressive Strength ◽  
Unconfined Compressive Strength ◽  
Coal Gangue ◽  
Hydration Time ◽  
Alkali Activated Slag ◽  
Microstructure Characteristics ◽  
Activated Coal ◽  
Activated Slag ◽  
Activated Coal Gangue ◽  
Alkali Activated

To accelerate the resource utilization of coal gangue and meet the strategic requirements of carbon neutralization, alkali-activated, slag-cemented coal gangue is applied in the preparation of solid waste-based road stabilization materials. Here, the cementation characteristics and microstructure characteristics of alkali-activated, slag-cemented coal gangue road stabilization materials are studied using the alkali equivalent and coal gangue aggregate ratio as experimental variables. The results show that with the increase in alkali equivalent from 1% to 7%, the unconfined compressive strength of the alkali-activated coal gangue road stabilization material initially increases and then decreases, with 3% being the optimal group in terms of stabilization, the aggregate ratio of coal gangue increases from 70% to 85%, and the 7-day unconfined compressive strength of the stabilized material decreases approximately linearly from 8.16 to 1.68 MPa. At the same time, the porosity gradually increases but still meets the requirements of the specification. With the increase in hydration time, a large number of hydration products are formed in the alkali slag cementation system, and they are closely attached to the surface of and interweave with the coal gangue to fill the pores, resulting in the alkali slag slurry and coal gangue being brought closer together.

Activation & Application Research in Concrete of Neimenggu High Aluminum Coal Gangue

2012 ◽  
Vol 450-451 ◽  
pp. 1400-1404
Author(s):  
Hai Li Cheng ◽  
Fei Hua Yang ◽  
Jie Zhang
Keyword(s):  
Setting Time ◽  
Chloride Ion ◽  
Coal Gangue ◽  
Application Research ◽  
Supplementary Cementitious Material ◽  
Chloride Ion Penetration ◽  
Activated Coal ◽  
Compressive Strength Of Concrete ◽  
Activated Coal Gangue ◽  
High Aluminum

In this paper, the heat-activated conditions of Neimenggu high aluminum coal gangue were studied, and then, the activated coal gangue as a supplementary cementitious material was used in concrete to investigate the application effect. The result shows that the optimal calcining temperature of high aluminum coal gangue is 800°C, the setting time of concrete was postponed, the slump was reduced and the resistance of concrete to chloride ion penetration was improved for the use of activated coal gangue. The compressive strength of concrete was enhanced when cement was replaced by 20%～30% activated coal gangue powder. Pozzolanic effect of activated coal gangue in the early age (7d) is higher and it can promote the hydration of cement with each other.

Effects of Kiln Dust-Activated Coal Gangue on the Properties of High-Content Slag Cement

2013 ◽  
Vol 753-755 ◽  
pp. 525-528
Author(s):  
Chun Mei Wang ◽  
Jing Wang ◽  
Li Rong Yang ◽  
Guang Dong Cao ◽  
Dan Yang Dong
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Setting Time ◽  
Coal Gangue ◽  
Slag Cement ◽  
Activated Coal ◽  
Kiln Dust ◽  
Activated Coal Gangue

The effects of amounts of the kiln dust-activated coal gangue on the setting time and compressive strength of high-content slag cement were investigated. The performance of sulphate resistance of cement with 30 wt.% kiln dust-activated coal gangue was evaluated. The results reveal that the setting time of high-content slag cement is prolonged. Appropriate kiln dust-activated coal gangue amounts can increase the compressive strength, while too much activated coal gangue (>30 wt.%) leads to the decrease in compressive strength. Cement with 10 wt.% kiln dust-activated coal gangue exhibits a good compressive strength. The performance of sulphate resistance of Portland cement with 30 wt.% kiln dust-activated coal gangue is distinctly enhanced, while that of high-content slag cement is improved to some extent.

Sign in / Sign up

Export Citation Format

Share Document