Study on backfill technology with paste-like material in mine abandoned roadway

According to the abandoned roadway left by the mining operation affected to the normal mining operation of the coal mining face,fly ash paste-like material were applied to the backfill test in the abandoned roadway. The basic physical and chemical properties of the material were studied when the backfill auxiliary material cont ent with 3%, 4% and 5%. An analysis was conducted on the backfill technology and backfill effect. The results showed that the auxiliary material content increased,the com pressive strength would be steadily increased. When the auxiliary material content was 5%,uniaxial compressive strength with 90 days was 6. 55 MPa,when the expansion rate was about 2. 4%,the backfill material could be well connected with the roof. The compressive strength could meet the requirements and within 30 min,the grout fluidity would be higher than 210 mm. In combination with the site system semi continuous stirring,continuous grouting and the rational circulation ratio,a pipe self flow conveying was realized,the backfill of the abandoned roadway eliminated the gas disaster,water disaster,roof disaster and other hidden dangers and the coal mining recovery rate wa s improved.