Exothermic behavior and drying shrinkage of alkali-activated slag concrete by low temperature-preparation method

2020 ◽  
Vol 262 ◽  
pp. 120056 ◽  
Author(s):  
Jichun Xiang ◽  
Yan He ◽  
Leping Liu ◽  
Hao Zheng ◽  
Xuemin Cui
Keyword(s):  
Low Temperature ◽  
Preparation Method ◽  
Drying Shrinkage ◽  
Alkali Activated Slag ◽  
Low Temperature Preparation ◽  
Activated Slag ◽  
Alkali Activated ◽  
Temperature Preparation

scholarly journals Mitigating the Drying Shrinkage and Autogenous Shrinkage of Alkali-Activated Slag by NaAlO2

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3499
Author(s):  
Bin Chen ◽  
Jun Wang ◽  
Jinyou Zhao
Keyword(s):  
Autogenous Shrinkage ◽  
Drying Shrinkage ◽  
Nitrogen Adsorption ◽  
Partial Substitution ◽  
Hydration Reaction ◽  
X Ray Diffraction ◽  
Na2o Content ◽  
Alkali Activated Slag ◽  
Activated Slag ◽  
Alkali Activated

The shrinkage of alkali-activated slag (AAS) is obviously higher than ordinary Portland cement, which limited its application in engineering. In this study, the effects of NaAlO2 in mitigating drying shrinkage and autogenous shrinkage of AAS were studied. To further understand the shrinkage mechanism, the hydration products and microstructures were studied by X-ray diffraction, scanning electron microscopy and nitrogen adsorption approaches. As the partial substitution rate of NaAlO2 for Na2SiO3 increased, the drying shrinkage and autogenous shrinkage reduced significantly. The addition of NaAlO2 could slow down the rate of hydration reaction and reduce the porosity, change the pore diameter and the composition of generated paste and cause more hydrotalcite and tetranatrolite generated—which contributed to reduced shrinkage. Additionally, raising the Na2O content rate caused obvious differences in drying shrinkage and autogenous shrinkage. As the Na2O content elevated, the drying shrinkage decreased and autogenous shrinkage increased. A high Na2O content would cause complete hydration reactions and provoke high autogenous shrinkage. However, incomplete hydration reactions left more water in the paste, and the evaporated water dramatically influenced drying shrinkage. The results indicate that addition of NaAlO2 could greatly mitigate the drying shrinkage and autogenous shrinkage of AAS.

scholarly journals Preparation and Mechanical Properties of Cemented Uranium Tailing Backfill Based on Alkali-Activated Slag

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Fulin Wang ◽  
Guoliang Chen ◽  
Lu Ji ◽  
Zhengping Yuan
Keyword(s):  
Preparation Method ◽  
High Strength ◽  
Cementitious Materials ◽  
Test Results ◽  
Alkali Activated Slag ◽  
Activated Slag ◽  
Cementing Material ◽  
Uranium Tailings ◽  
Cement Solidification ◽  
Alkali Activated

Backfilling disposal based on cement solidification is one of the ways to solve the environmental and safe problems of uranium tailing surface stacking. Alkali-activated slag, especially sodium silicate activated geopolymer, has become the preferred cementing material for the uranium tailing backfilling system because of its advantages of corrosion resistance and high strength. In this paper, uranium tailings and slag are taken as research objects, and the unconfined compressive strength (UCS) is taken as the main quality index. The preparation method of the cemented uranium tailing backfill based on alkali-activated slag was studied, hereinafter referred to as CUTB. The effects of additive amount, activator amount and activator modulus on the strength of CUTB were investigated. The results show that alkali-activated slag is an effective cementing material for the backfilling system of uranium tailing aggregate. The maximum UCS of 28 d age in the test groups is 16.45 MPa. Quicklime is an important additive for preparing CUTB. When the amount of quicklime is 0%, the early and late strengths of the filling body cannot be measured or at a very low level. At the age of 7 d, the order of each factor is additive amount > activator modulus > activator amount, but at the age of 28 d, the order of each factor is additive amount > activator amount > activator modulus. The test results can provide a basis for choosing cementitious materials for backfilling disposal of uranium tailings.

scholarly journals Understanding the drying shrinkage performance of alkali-activated slag mortars

2017 ◽  
Vol 76 ◽  
pp. 13-24 ◽  
Author(s):  
Hailong Ye ◽  
Christopher Cartwright ◽  
Farshad Rajabipour ◽  
Aleksandra Radlińska
Keyword(s):  
Drying Shrinkage ◽  
Alkali Activated Slag ◽  
Activated Slag ◽  
Alkali Activated

Shrinkage Behavior of Alkali-Activated Slag Cement Pastes

2018 ◽  
Vol 761 ◽  
pp. 45-48 ◽  
Author(s):  
Vladyslav Omelchuk ◽  
Guang Ye ◽  
Rayisa Runova ◽  
Igor I. Rudenko
Keyword(s):  
Autogenous Shrinkage ◽  
Drying Shrinkage ◽  
Chemical Shrinkage ◽  
Slag Cement ◽  
Cement Pastes ◽  
Alkali Activated Slag ◽  
Activated Slag ◽  
Mineral Additives ◽  
Alkali Activated ◽  
Shrinkage Behavior

Nowadays, alkali-activated cements (AACs) are the most promising alternatives to ordinary portland cement (OPC). Such cements characterized by better strength and corrosion resistance that determine improved durability of materials based on them. However, the shrinkage of AAC systems is noticeably higher compared with OPC. The purpose of this work was to study the shrinkage behavior of alkali-activated slag cement (AASC) pastes. To improve early age performance of AASCs – OPC and Ca(OH)2, as mineral additives, were added to the designed cement mixtures. The properties, like, flexural and compressive strength of cement mortars, chemical shrinkage, autogenous shrinkage and drying shrinkage of cement pastes were studied. The results showed that the chemical shrinkage, autogenous shrinkage and drying shrinkage at 28 days were between 0.064 – 0.074 ml/g, 4.5 – 7.9 mm/m and 3.3 – 4.9 mm/m, respectively. The relationship between the nature of alkaline components, the type of mineral additives and the shrinkage behavior of cements were discussed.

Basaltic Crushed Rock Stabilized with Cementitious Additives: Compressive Strength and Stiffness, Drying Shrinkage, and Capillary Flow Characteristics

2003 ◽  
Vol 1819 (1) ◽  
pp. 18-26 ◽  
Author(s):  
Srijib Chakrabarti ◽  
Jayantha Kodikara
Keyword(s):  
Capillary Rise ◽  
Blended Cement ◽  
Drying Shrinkage ◽  
Basaltic Rock ◽  
General Purpose ◽  
Binder Content ◽  
Alkali Activated Slag ◽  
Basaltic Rocks ◽  
Activated Slag ◽  
Alkali Activated

Research was undertaken to increase knowledge of the properties of local stabilized pavement materials to facilitate their wider use in road construction and rehabilitation. Laboratory tests involved testing for the unconfined compressive strength (UCS), shrinkage, and capillary behavior of crushed basaltic rocks stabilized with two conventional cementitious binders—general purpose cement and lime—and two cementitious binders comprising industrial waste products—blended cement and alkali-activated slag. The alkali-activated slag and blended cement significantly increased UCS of untreated material and performed as well as or better than such traditional binders as general purpose cement. Overall, lime performed poorly as a stabilizer of crushed basaltic rocks, primarily because the fine content containing clay minerals was not significant in the crushed basaltic rock composition. UCS of stabilized materials increased significantly as binder content increased; UCS could be described as a function of binder quantity. Ultimate shrinkage increased with binder content for general purpose cement and alkali-activated slag, but for blended cement, behavior was different. The rate of drying shrinkage was relatively high at the early stage of shrinkage. Generally, alkali-activated slag produced less shrinkage compared with general purpose and blended cements. Capillary rise and water absorption were also measured. Test results indicated that the rate of capillary rise and amount of water absorbed by the material matrix decreased with the increase of binder content. The research indicated that the use of binders with industrial by-products could be a viable option in stabilization of crushed basaltic rock materials.

scholarly journals Use of Industrial Waste Slag in Alkali-Activated Slag Ceramsite Concrete Hollow Blocks

2018 ◽  
Vol 8 (12) ◽  
pp. 2358 ◽  
Author(s):  
Zhenzhen Jiao ◽  
Ying Wang ◽  
Wenzhong Zheng ◽  
Wenxuan Huang ◽  
Xianyu Zhou
Keyword(s):  
Compressive Strength ◽  
Industrial Waste ◽  
Drying Shrinkage ◽  
Concrete Block ◽  
Na2o Content ◽  
Alkali Activated Slag ◽  
Viable Solution ◽  
Optimal Mix ◽  
Activated Slag ◽  
Alkali Activated

In this paper, a parametric experimental study developing the alkali-activated slag concrete hollow block (AASCHB) is discussed. Fourteen trial mixes of alkali-activated slag concrete containing pottery sand and ceramsite with different water-to-slag ratios, sand ratios, silicate moduli, and Na2O contents were evaluated to determine the optimal mix for high compressive strength and low drying shrinkage. All four factors evaluated were found to be significant for the desired properties. A series of 390 × 190 × 190 mm3 AASCHBs were prepared using the optimal mix with a water-to-slag ratio of 0.35, sand ratio of 0.64, silicate modulus of 1.2, and Na2O content of 8%. The compressive strength, flexural strength, water absorption, and moisture content tests of these blocks indicate that the resulting AASCHB can be classified under the strength grade of MU15 as a load-bearing hollow concrete block. The proposed AASCHBs appear to provide a viable solution to the environmental problems of industrial waste and cement production emissions, leading to more sustainable buildings without compromising structural performance.

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