In order to solve the filling demand of upward drift filling mining method in the broken rock area of a gold mine in Luoyang, fly ash-based foam concrete was used to fill the goaf. The slump test and uniaxial compression test were carried out to explore the influence of fly ash content on the compressive strength of filling body, and the cementitious mechanism of fly ash based foam concrete was analyzed. The results show that the foam concrete can control its flow state through the foaming rate (wet bulk density), and the slump values of the slurry with different cement contents are controlled between 24 cm and 27 cm. At this time, the slurry has a good flow performance and no bleeding phenomenon. Whether fly ash is added or not, the strength of foam concrete specimen can meet the strength requirements of upward drift filling mining method, but the costs of foam concrete materials can be reduced by 46.7％ by adding fly ash, and fly ash-based foam concrete has a good application prospect. The fly ash optimizes the pore structure by generating C-S-H gel and ettringite to improve the later strength of the filling body. In the industrial test of foam concrete, the total volume of goaf is 525 m³, the costs of filling materials are about 55,000 yuan, and the comprehensive filling cost is 42 yuan/t. The filling slurry has good leveling and no bleeding, and the strength of filling body is consistent with the indoor test values. The industrial test of filling has achieved the expected effect and solved the urgent problem of mine filling production.

Foam concrete  /  Fly ash content  /  Upward drift filling mining method  /  Compressive strength