Effect of micro-sized calcium carbonate on hydration behavior of CAC at 20 ℃

doi:10.3969/j.issn.1001-1935.2022.03.006

Abstract

Abstract:

Corundum castables were prepared using tabular corundum particles and fines,α-Al₂O₃ micro-powder,micro-sized calcium carbonate,calcium aluminate cement (CAC) and other raw materials.The effects of the micro-sized calcium carbonate on the hydration rate of CAC,the phase composition and the microstructure of the hydration products at 20 ℃ were studied.Meanwhile,the effect of the micro-sized calcium carbonate powder (0-1.5%,by mass) on the strength of CAC bonded corundum castables during curing was also explored.The results show that the slow hydration rate of CAC gives rise to the main hydration product of acicular CAH₁₀ after curing at 20 ℃ without adding micro-sized calcium carbonate;after adding micro-sized calcium carbonate,the hydration rate of CAC increases significantly,and the main hydration products change from acicular CAH₁₀ to lamellar C₄A$\bar{C}$H₁₁.The introduction of micro-sized calcium carbonate accelerates the hydration of CAC,increases the amount of hydration products,and significantly improves the curing strength of CAC bonded castables.

Key words: calcium aluminate cement, corundum castable, micro-sized calcium carbonate, hydration products, curing strength

摘要：

采用板状刚玉颗粒和细粉、α-Al₂O₃微粉、碳酸钙微粉、铝酸钙水泥(CAC)等原料制备了刚玉质浇注料,研究了20 ℃下碳酸钙微粉对CAC水化速率、水化产物的相组成和显微结构的影响,同时也探究了碳酸钙微粉加入量(0~1.5%,w)对CAC结合刚玉质浇注料养护过程中强度的影响。结果表明:在20 ℃下,未加入碳酸钙微粉时,CAC水化速率较慢,水化产物主要为针柱状的CAH₁₀;加入碳酸钙微粉后,CAC水化速率明显提升,且其主要的水化产物从针柱状的CAH₁₀转变成片状的C₄A$\bar{C}$H₁₁。碳酸钙微粉的引入加速了CAC的水化,使得水化产物数量增多,CAC结合浇注料的养护强度显著提升。

关键词: 铝酸钙水泥, 刚玉质浇注料, 碳酸钙微粉, 水化产物, 养护强度

CLC Number:

TQ175

Liu Mingyang, Wang Saixin, Ma Zhenyou, Jin Dongmei, Zhou Wenying, Mu Yuandong, Ye Guotian. Effect of micro-sized calcium carbonate on hydration behavior of CAC at 20 ℃[J]. Refractories, 2022, 56(3): 206-209.

刘明杨, 王赛鑫, 马振友, 晋冬梅, 周文英, 穆元冬, 叶国田. 20 ℃下碳酸钙微粉对铝酸钙水泥水化行为的影响[J]. 耐火材料, 2022, 56(3): 206-209.

Figures/Tables 8

Table 1 Formulations of corundum castables with different contents of micro-sized CaCO3

原料		w/%
原料		A0	A3	A5	A10	A15
板状刚玉	6~3 mm	30	30	30	30	30
	3~1 mm	20	20	20	20	20
	1~0.5 mm	13	13	13	13	13
	≤0.5 mm	13	13	13	13	13
	≤0.045 mm	9	8.7	8.5	8	7.5
α-Al₂O₃微粉	d₅₀=2.14 μm	10	10	10	10	10
碳酸钙微粉	d₅₀=1.69 μm	0	0.3	0.5	1.0	1.5
Secar 71水泥	d₅₀=13.6 μm	5	5	5	5	5

Table 2 Formulations of cement slurry with different contents of micro-sized CaCO3

原料		w/%
原料		B0	B3	B5	B10	B15
Secar 71水泥	d₅₀=13.6 μm	100	100	100	100	100
碳酸钙微粉 (外加)	d₅₀=1.69 μm	0	6	10	20	30
去离子水 (外加)		100	100	100	100	100

Table 3 Formulations of castable matrices with different contents of micro-sized CaCO3

原料		w/%
原料		C0	C3	C5	C10	C15
Secar 71水泥	d₅₀=13.6 μm	40	40	40	40	40
α-Al₂O₃微粉	d₅₀=2.14 μm	60	60	60	60	60
碳酸钙微粉 (外加)	d₅₀=1.69 μm	0	3	5	10	15
去离子水(外加)		100	100	100	100	100

Fig.1 Temperature evolution curves of slurry with different contents of micro-sized CaCO3 cured at 20 ℃

Fig.2 XRD patterns of castable matrices after curing at 20 ℃ for 12 and 24 h

Fig.3 SEM images of castable matrices without micro-sized CaCO3 after curing at 20 ℃ for 24 h

Fig.4 SEM images of castable matrices with micro-sized CaCO3 after curing at 20 ℃ for 24 h

Fig.5 Cold strength of castables specimens with varied micro-sized CaCO3 contents after curing at 20 ℃ for different durations

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