Abstract
This paper presents a scientific basis and reference for the application of ceramsite concrete in underground coal mines. Taking fly-ash ceramsite as raw material, a variety of mix proportions of C20 ceramsite concrete were proposed by changing the sand rate of concrete. The results showed that: (1) fly-ash ceramsite has different water absorption performance with different particle sizes. The water absorption stopped after soaked for 48 h. So, the ceramsite should be soaked for more than 48 h to prevent the cement from hydrating insufficient which affects the mechanical properties of the concrete. (2) Seven mix proportions of C20 ceramsite concrete were designed by changing the ceramsite proportion. The ceramsite proportion of 43% was determined as optimal scheme whose 28-day strength was 29.60 MPa and elastic modulus was 12.45 GPa. (3) The optimal scheme was applied and verified in the field. The early strength of ceramsite concrete promotes quickly, 3-day strength was 16.8 MPa, and the 28-day strength was 29.9 MPa. Compared with ordinary pebble concrete, ceramsite concrete can provide faster, higher strength support to the roadway. Meanwhile, ceramsite concrete have properties of lightweight, and its application will bring economic and social benefits.
Highlights
Fly-ash is mainly one of the industrial wastes in China
(2) Seven mix proportions of C20 ceramsite concrete were designed by changing the ceramsite proportion
The ceramsite proportion of 43% was determined as optimal scheme whose 28-day strength was 29.60 MPa and elastic modulus was 12.45 GPa. (3) The optimal scheme was applied and verified in the field
Summary
Fly-ash is mainly one of the industrial wastes in China. Fly-ash emissions are increasing in recent years with the development of energy industry. The compressive strength of samples with different ceramsite proportion is shown in Table 4 and Figure 8. Ceramsite concrete has better plasticity characteristics to adapt the initial large deformation of the roadway, and to maintain a good support strength. The aggregate, cement, and water were mixed evenly according to the designed proportion, pressed to a jet head by a pressure supply machine, and sprays those materials out after adding accelerator. According to the test data and curve (shown in Figure 12), it can be concluded that the initial strength (3-day strength) of ceramsite concrete is much higher than that of the pebble concrete. \ 10.0 16.5 27.0 rapidly, the 3-day strength was 16.8 MPa, and the 28-day strength reached 29.9 MPa. Compared with pebble concrete, the ceramsite concrete is able to provide more immediate and higher support for roadway
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