scholarly journals Polyvinyl-Alcohol-Modified Calcium Sulphoaluminate Cement Repair Mortar: Hydration and Properties

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7834
Author(s):  
Yongjie Bian ◽  
Yongbo Huang ◽  
Fuxin Li ◽  
Dong Dong ◽  
Honggen Zhao ◽  
...  
Keyword(s):  
Polyvinyl Alcohol ◽  
Mechanical Strength ◽  
Bonding Strength ◽  
Setting Time ◽  
Hydroxyl Group ◽  
Hydration Products ◽  
Clay Bricks ◽  
Repair Mortar ◽  
Calcium Sulphoaluminate ◽  
Calcium Sulphoaluminate Cement

Polyvinyl alcohol (PVA) and calcium sulphoaluminate (CSA) cement were used to prepare repair mortar for the restoration of the walls of a building built with bricks. The preparation, hydration, and properties of the PVA-modified CSA cement repair mortar were studied. Besides this, the mechanism by which PVA improves the bonding strength is also discussed. The results demonstrate that PVA prolongs the setting time of CSA cement, which is ascribed to PVA inhibiting the dissolution of C4A3$ (4CaO·3Al2O3·SO3) and the precipitation of AFt (3CaO·Al2O3·3CaSO4·26H2O) within the hydration age of 0~60 min. PVA lowers the mechanical strength of CSA cement repair mortar at the hydration age of 6 h. After 6 h, the mechanical strength is improved. PVA could also improve the bonding strength between CSA repair mortar and bricks. This is mainly ascribed to the Al ions in both the hydration products of CSA cement and the clay bricks reacting with the hydroxyl group of PVA and forming the chemical bond C-O-Al. Therefore, a tighter combination between CSA cement repair mortar and the clay bricks forms, thereby improving the bonding strength.

scholarly journals Influence of the Concentration of Seawater on the Early Hydration Properties of Calcium Sulphoaluminate (CSA) Cement: A Preliminary Study

Buildings ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 243
Author(s):  
Chuanlin Wang ◽  
Zeping Liu ◽  
Tengteng Zhang ◽  
Yuxuan Zhang ◽  
Zehong Liu ◽  
...  
Keyword(s):  
Mechanical Strength ◽  
Cement Paste ◽  
Early Stage ◽  
Setting Time ◽  
Cement Matrix ◽  
Chemical Shrinkage ◽  
High Concentration ◽  
Hydration Properties ◽  
Early Hydration ◽  
Calcium Sulphoaluminate

This research investigates the effect of seawater of different concentrations on the hydration process and microstructure of calcium sulphoaluminate (CSA) cement. It studies the CSA cement pastes via experiments carried out to determine the initial and final setting times, mechanical strength and chemical shrinkage with X-ray diffraction (XRD), scanning electron microscopy (SEM) and simultaneous differential thermal-thermogravimetric (DTA-TG) analysis. The DTA-TG and XRD results showed that the main hydration products were ettringite (AFt) and aluminum hydroxide in the CSA cement paste mixed with both freshwater and seawater, while a small amount of ettringite (AFt) became monosulfate (AFm) in the freshwater-mixed CSA cement. The SEM results demonstrate that seawater can improve the microstructure of CSA cement paste in the early stage of hydration (1 d) but impairs the microstructure of the CSA cement matrix in the later stage of hydration (7 d). The experimental results also indicate that a high concentration of seawater can extend the setting time, increase the chemical shrinkage and decrease the mechanical strength of CSA cement.

Study on Effect and Action Mechanism of Different Superplasticizer on Properties of Titanium Gypsum

2013 ◽  
Vol 468 ◽  
pp. 24-27
Author(s):  
Chuan Wei Du ◽  
Guo Zhong Li
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Chemical Modification ◽  
Mechanical Strength ◽  
Setting Time ◽  
Test Results ◽  
Hydration Products ◽  
Action Mechanism ◽  
Micro Structure ◽  
Modification Of Titanium

The chemical modification of titanium gypsum was made by calcium lignosulfonate, naphthalene and polycarboxylate superplasticizer. The effect of different superplasticizer on the physical properties of titanium gypsum was studied. The test results show that the standard consistency water, setting time and mechanical strength of titanium gypsum had changed to different extent with the three types of superplasticizer added. Naphthalene superplasticizer had best modification effect on titanium gypsum and its optimum content was 3%. When the naphthalene superplasticizer dosage was 3%, the 2h flexural strength and the 2h compressive strength of sample were 1.15MPa and 2.37MPa. The micro structure of titanium gypsum hydration products was analysed by SEM and the action mechanism of superplasticizer was analysed.

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%.

Several Common Retarders on Performance of Ultra-Early-Strength Grouting Material

2013 ◽  
Vol 477-478 ◽  
pp. 931-935
Author(s):  
Chang Zheng Sun ◽  
Xiao Ping Zhang ◽  
Hai Nan Zhao ◽  
Qiang Gao
Keyword(s):  
Mechanical Strength ◽  
Setting Time ◽  
Strength Properties ◽  
Preliminary Screening ◽  
Final Setting Time ◽  
Grouting Material ◽  
Early Strength

To explore retarders on performance of ultra-early strength grouting material, Retarder, which are commonly used in the market after a preliminary screening, are further tested and analyzed for initial fluidity, setting time and mechanical strength properties of super early strength grouting material. The results show that: When borax content is 0.4%, the initial fluidity, final setting time, workability, mechanical strength are the best.

Effect of Heat Setting Methods on Structures and Properties of High Strength Polyvinyl Alcohol Fibre

2015 ◽  
Vol 815 ◽  
pp. 643-648
Author(s):  
Yin Zhu ◽  
Jiong Xin Zhao
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Polyvinyl Alcohol ◽  
Setting Time ◽  
High Strength ◽  
Single Fibre ◽  
X Ray Diffraction ◽  
Heat Setting ◽  
Heat Treated ◽  
Setting Process

The effect of heat setting methods on the structures and mechanical properties of high strength polyvinyl alcohol (PVA) fibre is studied in this article. The microstructure and mechanical properties of heat treated PVA fibre is investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), and single fibre electronic tensile strength tester. Results show that the heat setting method with constant tension is a good heat setting method which can largely enhance the tensile strength of PVA fibre. During the heat setting process, the mechanical properties of PVA fibre are greatly affected by the temperature, tension and setting time. When the temperature is 220°C, tension is 5cN/dtex and setting time is 90sec, the tensile strength of PVA fibre increases from 12.0cN/dtex to 16.4cN/dtex in compare with the PVA fibre without heat setting

Cross‐linked cationic polyvinyl alcohol for improving mechanical strength of paper

2021 ◽  
pp. 51958
Author(s):  
Kaibin Li ◽  
Xiaorui Li ◽  
Dan Wang ◽  
Chunsheng Zhou ◽  
Yiding Shen
Keyword(s):  
Polyvinyl Alcohol ◽  
Mechanical Strength
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