Fibre Reinforced Paste Fill (FRPF) is an original idea designed to help solve the large problem of weak paste fill in underground metalliferous mines. Weak fill promotes problems with both production and safety in mining operations. It can lead to increased dilution of ore, increased mining and milling costs, excess down time and can also lead to failures in development headings, presenting a safety concern for workers. Typically, mines would strengthen their fill, by continuing to add more cement until it holds. This is the case with Cannington and many other similar operations world wide. This method of strengthening results in huge excess costs which could be reduced with the introduction of FRPF. Fibre Reinforced Paste Fill uses the basic idea of creating a composite by adding fibres to paste fill in order to increase the strength properties and integrity of the fill reducing the need for excess cement.
The samples were set in 50mm diameter x 125mm long PVC moulds. The samples consisted of 3, 5 and 8% cement content mixes, each with 3 samples of 0, 1, 3 and 5kg/m3 fibre contents. These samples were cured at high temperatures and high humidity’s, resembling insitu conditions.
The samples were tested using uniaxial compressive and brazilian tensile tests. The UCS results were compared against other world fills and it was found that the introduction of reinforcing fibres increased the UCS values of the fills, while the brazilian tensile strengths of the fills did not react as strongly to the fibres. The observations made during the UCS and BTS tests proved that with the inclusion of fibres into the fills the integrity of the samples was increased dramatically, with the fibres binding the samples together and not breaking up as per usual.
Further research is recommended on different types of fibres, including natural fibres, recycled waste fibres or specially designed synthetic fibres for use in paste fill.