Influence of Pre-Curing on Macroscopic Properties and Microstructure of Silicon Calcium Slag Composite Autoclaved Aerated Concrete

doi:10.16552/j.cnki.issn1001-1625.2025.0721

Abstract

Abstract:

In this paper， silicon calcium slag， slag， and desulfurization gypsum were used as the main raw materials. By adjusting the process parameters such as fresh slurry temperature， pre-curing temperature and pre-curing time， the influence of the preparation process of silicon calcium slag composite autoclaved aerated concrete on dry density， compressive strength， and microstructure was studied. The results show that with the increase of fresh slurry temperature， the compressive strength of the test block shows a trend of increasing first and then decreasing， reaching a peak at 45 ℃， an increase of 96.3% compared to 25 ℃. With the increase of pre-curing temperature， the compressive strength of the test block shows a trend of increasing first and then decreasing. When the pre-curing temperature is 62.5 ℃， the compressive strength increases by 19.6% compared to the 52.5 ℃ group. When the pre-curing time is 8 h， the tobermorite is arranged in a large leaf like orderly manner， and the test block reaches the A05 strength level. If the pre-curing time is too short （<8 h）， it will cause uneven distribution of the main hydration product tobermorite. If the pre-curing time is too long （>8 h）， it will cause interface degradation. By optimizing the process parameters （fresh slurry temperature of 45 ℃， pre-curing temperature of 62.5 ℃， pre-curing time of 8 h）， the mechanical properties and pore uniformity of silicon calcium slag composite autoclaved aerated concrete can be synergistically improved， providing theoretical support for the industrial application of calcium silicate slag building materials.

Key words: silicon calcium slag, autoclaved aerated concrete, pre-curing, mechanical property, microstructure

CLC Number:

TU528.2

LIANG Xinxing, ZHANG Jingshen, WANG Chaosheng, LIANG Liguizu, LIU Ze, ZHANG Tong, ZHU Yingcan. Influence of Pre-Curing on Macroscopic Properties and Microstructure of Silicon Calcium Slag Composite Autoclaved Aerated Concrete[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2026, 45(1): 40-46.

Figures/Tables 11

Table 1 Chemical composition of raw materials

Composition	Mass fraction/%
Composition	SiO₂	Al₂O₃	Fe₂O₃	CaO	MgO	SO₃	Other	LOI
Silicon calcium slag	25.49	6.12	2.17	39.85	3.04	0.56	1.83	20.94
Quartz powder	90.19	2.80	2.75	2.49	0.37	0.70	0.70	—
Desulfurization gypsum	1.83	0.59	0.37	31.63	1.68	40.30	1.40	22.20
Slag	32.25	16.49	0.73	38.23	9.85	0.01	2.22	0.22
Quicklime	1.79	1.67	—	79.70	—	2.30	6.74	7.80

Table 2 Design of experimental parameters

Sample No.	Fresh slurry temperature /℃	Sample No.	Pre-curing temperature/℃	Sample No.	Pre-curing time/h
JT1	25	PT1	32.5	Pt1	5
JT2	35	PT2	42.5	Pt2	6
JT3	45	PT3	52.5	Pt3	8
JT4	55	PT4	62.5	Pt4	10
JT5	65	PT5	72.5	Pt5	12
		PT6	82.5

Fig.1 Dry density and compressive strength of AAC

Fig.2 Volume expansion ratio and expansion rate curves of at different fresh slurry temperatures AAC at different fresh slurry temperatures

Fig.3 Dry density and compressive strength of AAC at different pre-curing temperatures

Fig.4 Dispersion degree of AAC at different

Fig.5 Hardening rate of AAC at different pre-curing temperatures

Table 3 Demoulding time of AAC at different pre-curing temperatures

Sample No.	PT1	PT2	PT3	PT4	PT5	PT6
Demoulding time/h	＞12	12	10	8	8	8

Fig.6 Dry density and compressive strength of AAC under different pre-curing time

Fig.7 XRD patterns of AAC under different pre-curing time

Fig.8 SEM images of AAC under different pre-curing time

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