1 Introduction
2 Materials and Methods
2.1 Raw Materials
Density (g/cm3) | Specific area (m2/kg) | Flexural strength (MPa) | Compressive strength (MPa) | Setting time (min) | |||
---|---|---|---|---|---|---|---|
3-day | 28-day | 3-day | 28-day | Initial | Final | ||
3.14 | 362 | 6.5 | 8.7 | 36.5 | 60.4 | 113 | 162 |
Fineness modulus | 2.46 |
Apparent density (kg/m3) | 2470 |
Bulk density (loose condition) (kg/m3) | 1360 |
Bulk density (dense condition) (kg/m3) | 1580 |
Saturated-surface-dry water absorption (%) | 5.0 |
2.2 Design of Partition Panel
Panel ID | Opening type | Panel thickness (mm) | The number of openings | Opening size (mm) | Percentage of opening (%) | Panel area density (kg/m2) | Concrete density (kg/m3) |
---|---|---|---|---|---|---|---|
90C | Circular | 90 | 7 | d = 50 | 25.4 | ≤ 110 | ≤ 1635 |
90R | Rounded rectangular | 90 | 5 | 80 × 40, R = 3 | 29.6 | ≤ 110 | ≤ 1735 |
120C | Circular | 120 | 6 | d = 65 | 27.6 | ≤ 140 | ≤ 1610 |
120R | Rounded rectangular | 120 | 5 | 80 × 60, R = 3 | 33.3 | ≤ 140 | ≤ 1745 |
2.3 Preparation of CRFA-LWC
No. | C/C | Target concrete density (kg/m3) | SF (%) | The content of the concrete materials (kg/m3) | ||||
---|---|---|---|---|---|---|---|---|
Cement | Water | Water reducer | Air-entraining agent | CRFA | ||||
AR18-1 | 1.8 | 1550 | 65 | 503 | 161 | 12.1 | 3.82 | 906 |
AR18-2 | 1.8 | 1650 | 65 | 536 | 171 | 12.9 | 2.95 | 964 |
AR18-3 | 1.8 | 1750 | 65 | 568 | 181 | 13.6 | 2.04 | 1023 |
AR22-1 | 2.2 | 1550 | 85 | 445 | 157 | 11.6 | 3.56 | 980 |
AR22-2 | 2.2 | 1650 | 85 | 474 | 167 | 12.3 | 2.75 | 1043 |
AR22-3 | 2.2 | 1750 | 85 | 503 | 177 | 13.1 | 2.11 | 1106 |
AR24-1 | 2.4 | 1550 | 100 | 421 | 159 | 11.8 | 3.58 | 1011 |
AR24-2 | 2.4 | 1650 | 100 | 448 | 169 | 12.5 | 2.33 | 1076 |
2.4 Characterization of CRFA-LWC
3 Results and Discussion
3.1 Workability of CRFA-LWC
Sample ID | AR18-1 | AR18-2 | AR18-3 | AR22-1 | AR22-2 | AR22-3 | AR24-1 | AR24-1 |
---|---|---|---|---|---|---|---|---|
Density (kg/m3) | 1565 | 1622 | 1706 | 1579 | 1661 | 1718 | 1586 | 1674 |
Slump flow (mm) | 109 | 106 | 105 | 105 | 102 | 101 | 93 | 83 |
3.2 Strength of CRFA-LWC
3.3 Strength of CRFA-LWC Partition Panels
3.4 Pore Structure of CRFA-LWC
3.5 Dry Shrinkage of CRFA-LWC
3.6 Economic Analysis of CRFA-LWC
Material | Cement | River sand | CRFA | Ceramsite |
---|---|---|---|---|
Price (RMB/ton) | 450 | 190 | 60 | 609 |
Concrete | Curing condition | Content (kg/m3) | Price (RMB/m3) | |||
---|---|---|---|---|---|---|
Cement | River sand | CRFA | Ceramiste | |||
ACC | Autoclave | 350 | 600 | – | 325 | 469.5 |
AR22-2 | Autoclave-free | 474 | – | 1043 | – | 275.9 |
AR22-3 | Autoclave-free | 503 | – | 1106 | – | 292.7 |
4 Conclusions
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The LWC with a CRFA-to-cement ratio of smaller than 2.2 can satisfy the target density and the workability requirements. The strength of the concrete correlates negatively with the ratio of the CRFA to the cement. Given that the price of cement is higher than that of CRFA, the optimal CRFA-to-cement ratio for preparing the LWC partition panel is 2.2.
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The pores of the CRFA-LWC have a diameter of smaller than 0.17 mm, and the diameter of 89% of the pores is less than 0.05 mm.
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The drying shrinkage of the CRFA-LWC decreases as the curing period of the samples extends. To fulfill the drying shrinkage requirements stipulated by Chinese standard JC/T 169-2016, the CRFA-LWC should be cured for at least 10 days. As the period between the preparation and the on-site construction of the wall panels is usually longer than 10 days, the necessary curing period of 10 days does not affect the application of the CRFA-LWC.
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At a similar thickness and panel area density, the CRFA-LWC partition panel with the rounded rectangular cross section presents higher compressive strength than that with the circular cross section. Thus, the optimal cross section of the CRFA-LWC partition panels is a rounded rectangular one.
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Mixture proportion AR22-3 with a CRFA-to-cement ratio of 2.2 and a target density of 1750 kg/m3 is suitable for the panel with a thickness of 90 mm, and mixture proportions AR22-2 and AR22-3 with a similar CRFA-to-cement ratio of 2.2 and a target density of 1650 and 1750 kg/m3, respectively, suit the panel with a thickness of 120 mm.
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The material cost of the CRFA-LWC is around 40% lower than that of the autoclaved ceramsite concrete. Moreover, enjoying an autoclave-free curing process, the production of the CRFA-LWC will be of remarkable economic benefit.