Effect of Gypsum on Hydration Degree and Structure of Hardened Paste of Alite-Strontium Calcium Sulphoaluminate Cement

2011 ◽  
Vol 306-307 ◽  
pp. 1024-1028
Author(s):  
Qiu Ying Li ◽  
Ling Chao Lu ◽  
Shou De Wang
Keyword(s):  
Compressive Strength ◽  
Cement Paste ◽  
Cement Clinker ◽  
Hardened Cement ◽  
Hydration Degree ◽  
Synthesis Conditions ◽  
Sulphoaluminate Cement ◽  
Calcium Sulphoaluminate ◽  
Calcium Sulphoaluminate Cement ◽  
Curing Age

Synthesis conditions and performance of alite-strontium calcium sulphoaluminate cement have been studied by introducing strontium calcium sulphoaluminate into Portland cement clinker. The effects of gypsum on compressive strength, hydration degree and structure of hardened alite-strontium calcium sulphoaluminate cement paste were studied in this paper. Composition and structure of the hardened cement paste were analyzed by XRD and SEM. Results show that appropriate content of gypsum could contribute to the hydration of alite-strontium calcium sulphoaluminate cement. When gypsum content is 9%, the compressive strengths for 1d, 3d and 28d curing age are 30.7MPa, 59.5MPa and 105.5MPa, and the corresponding hydration degree are 40.4%, 57.5% and 85.8%, respectively. The hydration products of alite-strontium calcium sulphoaluminate cement are mainly ettringite (AFt), Ca(OH)2, C-S-H gel. Large amount of AFt formed at early curing age provides a sound basis for early compressive strength, and a lot of C-S-H gel generated at later curing age increases the density of the hardened paste.

Influence of MgO on Sintering and Property of Belite-Barium Calcium Sulphoaluminate Cement

2012 ◽  
Vol 152-154 ◽  
pp. 68-73
Author(s):  
Ling Chao Lu ◽  
Shou De Wang ◽  
Hui Wang
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
Compressive Strength ◽  
Low Temperatures ◽  
Sintering Process ◽  
Sulphoaluminate Cement ◽  
Calcium Sulphoaluminate ◽  
Orthogonal Tests ◽  
Calcium Sulphoaluminate Cement ◽  
Curing Age

The effect of MgO on performance of belite-barium calcium sulphoaluminate cement (B-CBAS) was investigated through orthogonal tests. The results show that the formation of C3S can be improved at low temperatures by mixing MgO. SO3 decreasing the viscosity of fused mass in sintering process was beneficial to solid solution of MgO in B-CBAS clinker. The solid solubility of MgO in B-CBAS was higher than that of Portland cement, which indicated that high-magnesium limestone can be used in B-CBAS. Even MgO content reached 5.14%, the soundness of B-CBAS was still in safe, whose compressive strength at 3d and 28d curing age were 49.1MPa and 81.9MPa. This indicated that this kind of cement has good mechanical properties.

Determination of Tricalcium Silicates Crystal Forms in Belite-Barium Calcium Sulphoaluminate Cement

2014 ◽  
Vol 541-542 ◽  
pp. 204-208
Author(s):  
Yan Ting Zhao ◽  
Xi Chen ◽  
Ling Chao Lu ◽  
Yong Bo Huang ◽  
Jie Zhang
Keyword(s):  
Cement Clinker ◽  
X Ray Diffraction ◽  
Crystal Forms ◽  
Sulphoaluminate Cement ◽  
Cement System ◽  
Calcium Sulphoaluminate ◽  
Diffraction Peaks ◽  
Method Of Extraction ◽  
Calcium Sulphoaluminate Cement

Chemical method of extraction was adopted in the study, and aqueous solution of potassium hydroxide and sucrose (KOSH) was used to obtain the clinker rich in silicate phases (alite and belite) in order to get the crystal forms of tricalcium silicates (C3S) in the belite-barium calcium sulphoaluminate cement clinker. The crystal forms of C3S were finally determined by XRD (X-ray diffraction) spectrums through its characteristic windows of the diffraction spectrums. Results shows that, C3S exists in the innovative cement system mainly in the form of M1; C2.75B1.25A3can completely dissolve in KOSH solution while its dissolution is inhibited in the cement system; after KOSH treatment, diffraction peaks of C4AF disappear totally and peaks of C3A has weakened to great extent; for the cement clinker, the clinker ground for 90min has the best extraction rate.

Influences of Microelement on Microstructure and Mechanical Performance of Alite-Strontium Calcium Sulphoaluminate Cement

2010 ◽  
Vol 168-170 ◽  
pp. 466-471 ◽  
Author(s):  
Qiu Ying Li ◽  
Ling Chao Lu ◽  
Shou De Wang
Keyword(s):  
Mechanical Performance ◽  
Sintering Temperature ◽  
Cementitious Material ◽  
Cement Clinker ◽  
Testing Conditions ◽  
Sulphoaluminate Cement ◽  
Portland Cement Clinker ◽  
New Type ◽  
Calcium Sulphoaluminate ◽  
Calcium Sulphoaluminate Cement

Alite-strontium calcium sulphoaluminate cement, a new type of cementitious material, is synthesized by combining strontium calcium sulphoaluminate with minerals of Portland cement clinker. The influences of excessive SO3 and SrO on the microstructure and performances of this cement are studied by XRD, SEM-EDS and lithofacies. The results show that the optimal excessive mass fraction of SO3 and SrO are 50% and 80%. The compressive strength of the cement prepared under the testing conditions reaches to 32.8MPa, 66.8MPa and 126.4MPa at 1d, 3d and 28d curing ages, respectively. The additions of SO3 and SrO are benefit to improve the content of strontium calcium sulphoaluminate, and promote the formation of alite at low sintering temperature.

scholarly journals Calcination of Calcium Sulphoaluminate Cement Using Pyrite-Rich Cyanide Tailings

Crystals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 971
Author(s):  
Kaiwei Dong ◽  
Feng Xie ◽  
Wei Wang ◽  
Yongfeng Chang ◽  
Chunlin Chen ◽  
...  
Keyword(s):  
Gold Mining ◽  
Mining Industry ◽  
Cement Clinker ◽  
Optimal Conditions ◽  
Strength Criteria ◽  
Calcination Process ◽  
Sulphoaluminate Cement ◽  
Tailings Dams ◽  
Calcium Sulphoaluminate ◽  
Calcium Sulphoaluminate Cement

Pyrite-rich cyanide tailings (CTs) are industrial hazardous solid wastes arising from the gold mining industry. Every year, hundreds of millions of tons of cyanide tailings are produced and discharged to tailings dams. It is of great significance to dispose of cyanide tailings harmlessly and resourcefully. The feasibility of calcination of calcium sulphoaluminate (CSA) cement clinker using pyrite-rich cyanide tailings as Fe2O3 and SO3 sources was investigated for this paper. The behavior of pyrite during the calcination of cyanide tailings under various calcination conditions and the properties of calcium sulphoaluminate cement clinker were examined. The results show that it is feasible to produce calcium sulphoaluminate cement clinker using pyrite-rich cyanide tailings. The optimal conditions for the calcination of calcium sulphoaluminate cement using pyrite-rich cyanide tailings are confirmed. During the calcination process, the cyanides decompose into carbonate, CO2, and N2. The pyrite decomposes into Fe2O3 and SO2, and they react with CaO and Al2O3 to form the intermediates of CaSO4, 2CaO·Fe2O3, and CaO·2Al2O3, which further react to form 3CaO·3Al2O3·CaSO4, 4CaO·Al2O3·Fe2O3, and 12CaO·7Al2O3. The calcium sulphoaluminate cement prepared by pyrite-rich cyanide tailings exhibits excellent mechanical properties and meets the compressive strength criteria of 42.5 grade calcium sulphoaluminate cement.

Mechanical Properties of Alite-Calcium Barium Sulphoaluminate Cement Concrete

2008 ◽  
Vol 400-402 ◽  
pp. 121-124
Author(s):  
Zong Hui Zhou ◽  
Ling Chao Lu ◽  
Xing Kai Gao ◽  
Xin Cheng
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Portland Cement ◽  
Cement Paste ◽  
Early Age ◽  
Hardened Cement ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Hardened Cement Paste ◽  
Sulphoaluminate Cement

In this paper, preparation and mechanical properties of Alite-calcium barium sulphoaluminate (Alite-C2.75B1.25A3 ) cement concrete were studied. The results showed the compressive strength of Alite-C2.75B1.25A3 cement concrete was much higher than that of Portland cement concrete, especially the early-age compressive strength. The 24-hour compressive strength of Alite-C2.75B1.25A3 cement concrete could reach 22.81Mpa for w/c=0.45, 17.29Mpa for w/c=0.50 and 17.04Mpa for w/c=0.55 respectively. They were about 50 to 65 percent higher than those of Portland cement concrete. The 7-day compressive strength could reach about 80 to 90 percent of 28-day strength for Alite-C2.75B1.25A3 cement concrete. The 28-day strength could reach 55.85Mpa for w/c=0.45, 48.01Mpa for w/c=0.50 and 44.21Mpa for w/c=0.55 respectively. The results of SEM showed the interfaces between the hardened cement paste and aggregates in Alite-C2.75B1.25A3 cement concrete were more compact than those in Portland cement concrete. Distribution of particulate bulk was more uniformity and a majority of clinker particles was wrapped by hydrated gel in Alite-C2.75B1.25A3 concrete. And, the structure of Alite-C2.75B1.25A3 cement concrete was much more compact than that of Portland cement concrete.

Performance of Belite-Barium Calcium Sulphoaluminate Cement Prepared by Substituting Fly Ash for Clay

2011 ◽  
Vol 306-307 ◽  
pp. 1066-1070
Author(s):  
Pi Qi Zhao ◽  
Wen Zong ◽  
Shou De Wang ◽  
Gui Yun Wang ◽  
Ling Chao Lu
Keyword(s):  
Sintering Temperature ◽  
Cement Clinker ◽  
Petrographic Analysis ◽  
X Ray Diffraction ◽  
Sulphoaluminate Cement ◽  
Speed Up ◽  
Calcium Sulphoaluminate ◽  
And Performance ◽  
Sintering Condition ◽  
Calcium Sulphoaluminate Cement

The mineral structure and performance of belite-barium calcium sulphoaluminate cement clinkers were investigated by petrographic analysis, X-ray diffraction and scanning electron microscopy. The experimental results showed that the minerals of calcium barium sulphoaluminate (C2.75B1.25A3) and C2S could coexist in the belite-barium calcium sulphoaluminate cement clinker, and the optimal sintering temperature was 1380°C, at which, more C2.75B1.25A3was formed, well developed and also evenly distributed in the optimal sintering condition. If the sintering temperature exceeded 1380°C, the decomposition of C2.75B1.25A3 would speed up and the C3S became inactivate for its excessive development. In the optimal sintering condition, the compressive strength of the prepared cement at 3, 7, 28 d were 32.6, 47.9, 88.5 MPa respectively, which exhibited excellent mechanical properties.

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