Effect of calcium sulfoaluminate and MgO expansive agent on the mechanical strength and crack resistance of concrete

2021 ◽  
Vol 299 ◽  
pp. 123833
Author(s):  
Jinjun Guo ◽  
Shiwei Zhang ◽  
Cuige Qi ◽  
Lin Cheng ◽  
Lin Yang
Keyword(s):  
Mechanical Strength ◽  
Crack Resistance ◽  
Calcium Sulfoaluminate ◽  
Expansive Agent

scholarly journals Effect of Flue Gas Desulfurization Gypsum on the Properties of Calcium Sulfoaluminate Cement Blended with Ground Granulated Blast Furnace Slag

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 382 ◽  
Author(s):  
Danying Gao ◽  
Zhenqing Zhang ◽  
Yang Meng ◽  
Jiyu Tang ◽  
Lin Yang
Keyword(s):  
Blast Furnace ◽  
Mechanical Strength ◽  
Flue Gas ◽  
Blast Furnace Slag ◽  
Setting Time ◽  
Flue Gas Desulfurization ◽  
Calcium Sulfoaluminate Cement ◽  
Calcium Sulfoaluminate ◽  
Granulated Blast Furnace Slag ◽  
Furnace Slag

This work aims to investigate the effect of additional flue gas desulfurization gypsum (FGDG) on the properties of calcium sulfoaluminate cement (CSAC) blended with ground granulated blast furnace slag (GGBFS). The hydration rate, setting time, mechanical strength, pore structure and hydration products of the CSAC-GGBFS mixture containing FGDG were investigated systematically. The results show that the addition of FGDG promotes the hydration of the CSAC-GGBFS mixture and improves its mechanical strength; however, the FGDG content should not exceed 6%.

scholarly journals Shrinkage and Mechanical Properties of Self-Compacting SFRC With Calcium-Sulfoaluminate Expansive Agent

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 588 ◽  
Author(s):  
Changyong Li ◽  
Pengran Shang ◽  
Fenglan Li ◽  
Meng Feng ◽  
Shunbo Zhao
Keyword(s):  
Mechanical Properties ◽  
Steel Fiber ◽  
Volume Fraction ◽  
Cementitious Materials ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Steel Fiber Reinforced Concrete ◽  
Volume Stability ◽  
Calcium Sulfoaluminate ◽  
Expansive Agent

With the premise of ensuring workability on a fresh mixture, the volume stability of hardened self-compacting steel fiber reinforced concrete (SFRC) becomes an issue due to the content of cementitious materials increased with the volume fraction of steel fiber. By using the expansive agent to reduce the shrinkage deformation of self-compacting SFRC, the strength reduction of hardened self-compacting SFRC is another issue. To solve these issues, this paper performed an experimental investigation on the workability, shrinkage, and mechanical properties of self-compacting SFRC compared to the self-compacting concrete (SCC) with or without an expansive agent. The calcium-sulfoaluminate expansive agent with content optimized to be 10% mass of binders and the steel fiber with a varying volume fraction from 0.4% to 1.2% were selected as the main parameters. The mix proportion of self-compacting SFRC with expansive agent was designed by the direct absolute volume method, of which the steel fibers are considered to be the distributed coarse aggregates. Results showed that rational high filling and passing ability of fresh self-compacting SFRC was ensured by increasing the binder to coarse-aggregate ratio and the sand ratio in the mix proportions; the autogenous and drying shrinkages of hardened self-compacting SFRC reduced by 22.2% to 3.2% and by 18.5% to 7.3% compared to those of the SCC without expansive agent at a curing age of 180 d, although the expansion effect of expansive agent decreased with the increasing volume fraction of steel fiber; the mechanical properties, including the compressive strength, the splitting tensile strength, and the modulus of elasticity increased with the incorporation of an expansive agent and steel fibers, which met the design requirements.

scholarly journals Hydration of Calcium Sulfoaluminate-Based Binder Incorporating Red Mud and Silica Fume

2019 ◽  
Vol 9 (11) ◽  
pp. 2270 ◽  
Author(s):  
Yubin Jun ◽  
Jae Hong Kim ◽  
Taewan Kim
Keyword(s):  
Compressive Strength ◽  
Silica Fume ◽  
Red Mud ◽  
Drying Shrinkage ◽  
Pozzolanic Activity ◽  
Main Reaction ◽  
Main Reaction Product ◽  
Replacement Level ◽  
Calcium Sulfoaluminate ◽  
Expansive Agent

This study investigated the properties of hardened pastes made with calcium sulfoaluminate expansive agent (CSA), red mud, and silica fume. Five different ratios of 10:90, 20:80, 30:70, 40:60, and 50:50 were applied as the weight ratios of CSA and red mud. Red mud was replaced with 0, 5, and 10% silica fume by weight. Compressive strength, drying shrinkage, XRD, MIP, and SEM/EDS of the hardened pastes were performed. The results indicated that as the amount of CSA increased (i.e., as the amount of red mud decreased) up to 30%, sample strengths showed a tendency to increase. The main reaction product of the pastes was expansive ettringite, which was formed from the consumption of ye’elimite, anhydrite, gypsum, and Ca(OH)2. It was expected that C-S-H would be formed by the reaction of C2S in red mud; however, C-S-H phase was not present, and the pozzolanic activity due to the use of silica fume did not occur. The increase of CSA replacement level was effective for controlling the drying shrinkage of the samples. However, 50% replacement level of CSA induced excessive expansion, leading to the reduction in strength. It was found that the excessive expansion in the sample was reduced by the addition of silica fume.

scholarly journals Effect of expansive agent and internal curing agent on crack resistance of C50 silica fume wet-mix shotcrete

2019 ◽  
Vol 11 (1) ◽  
pp. 168781401881916 ◽  
Author(s):  
Feng Wei Ning ◽  
Yue Bo Cai ◽  
Yin Bai ◽  
Bo Chen ◽  
Feng Zhang
Keyword(s):  
Relative Humidity ◽  
Crack Resistance ◽  
Silica Fume ◽  
Stress Test ◽  
High Strength ◽  
Internal Curing ◽  
Ring Test ◽  
Curing Agent ◽  
Volume Deformation ◽  
Expansive Agent

High-strength shotcrete is always needed to strengthen rock support. However, it will reversely increase the crack risk. Crack normally goes against the durability and shortens the service life of shotcrete. The objective of this article was to improve the crack resistance of shotcrete with expansive agent and internal curing agent. C50 shotcrete with 10% of silica fume was taken as reference mix composition. Ring test and thermal stress test simulating actual temperature, relative humidity, and constraint were carried out to directly assess crack resistance. Restrained deformation, autogenous volume deformation, and pore structure were measured to study how expansive agent and internal curing agent resisted crack. The results indicated that 4% of expansive agent was enough to improve crack resistance of C50 shotcrete. It could fill internal pores and produce compressive pre-stress at earlier age which could be used to compensate shrinkage at later age. Furthermore, the crack resistance of C50 shotcrete could be further promoted when internal curing agent was employed together with expansive agent. The internal curing agent was able to reduce auto-shrinkage by decreasing the loss of internal relative humidity. In addition, it could also enhance the hydration degree of expansive agent, which would strengthen the role of expansive agent on resisting crack.

scholarly journals Development of Eco-Friendly Cement Using a Calcium Sulfoaluminate Expansive Agent Blended with Slag and Silica Fume

2021 ◽  
Vol 11 (1) ◽  
pp. 394
Author(s):  
Taewan Kim ◽  
Ki-Young Seo ◽  
Choonghyun Kang ◽  
Tak-Kee Lee
Keyword(s):  
Silica Fume ◽  
Mechanical Performance ◽  
Hydration Product ◽  
Early Age ◽  
Low Carbon ◽  
Calcium Sulfoaluminate ◽  
Mixing Ratios ◽  
Expansive Agent ◽  
Binder Ratio

This is an experimental study on the development of a low-carbon, eco-friendly cement containing a calcium sulfoaluminate expansive agent (CSAe), slag, and silica fume (SF). The cement to be developed has a low water/binder ratio (w/b) of 0.5 and is designed to be used for structural purposes, with focus on its mechanical performance. CSAe, slag, and SF were mixed at various mixing ratios. The main hydration product of the slag-based CSAe cement in the experiment was ettringite. Substituting less than 30% of CSAe showed a sufficient level of mechanical performance; that is, the material could be used as structural cement. SF controlled the excessive expansion of CSAe. However, since the developed slag-CSAe-SF cement has low early age (1 d) strength, follow-up research is needed for improvement.

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