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    ​​​​​Project Reference: Optimising Cemented Paste Fill using MasterRoc MF 505C​

    Location: Western Australia
    Market sector: Underground Construction
    Products used: ​​​MasterRoc MF 505C​ a concentrated polymer admixture used to improve cementitious mining backfill mixes

    The Background

    Darlot Gold Mine, operated by Gold Fields Australia, is situated 120 kilometres north of Leonora and 58 kilometres east of Leinster in the Yandal Greenstone Belt (Western Australia). Darlot underground complex utilises paste fill to provide static support for all voids in Lode 1. The required paste strength and cement content vary depending on the planned exposure. Curing time is also dependent on the mix used. Historical curing times for undercut and side exposures are approximately 20 days Current practice has paste development for mixes with cement content ≥2.5% undertaken at 4 days after finishing paste fill.

    The Challenge 

    Darlot required a faster mining cycle to mine the new ore body efficiently. Master Builders Solutions was engaged to assist with the improvement of the paste fill mix utilising chemical admixtures. Paste development and exposure from stoping commenced early to avoid cement content being reduced. Based on laboratory and site-based trial results, MasterRoc 505C was added to all Stage one (plug) pours in Lode 1 as the first pour with chemical addition began in April 2017.

    Our Solution

    Laboratory and large-scale (site-based) trials were undertaken using MasterRoc MF 505C with aim of increasing the quality of paste fill, in order that paste development, side exposure and undercut curing times could be reduced and Lode 1 extraction rate increased. The greatest strength gain was observed within the 14 – 28 day undercut curing window, with 400ml per wet tonne chemical addition. Based on trial results to date, the addition of MasterRoc MF 505C to paste fill mix will allow a two-day reduction in undercut curing time compared to LOM plan.​

    Project Facts at a Glance​

    • Ability to transport paste longer distances with the addition of the MasterRoc MF 505C
    • Cement reduction of 1% can be obtained if paste exposure is not time-constrained.

    Product Facts at a Glance

    • ​​MasterRoc MF 505C​ admixture aids in the produ​ction of backfill mixes​  by reducing water content for a given consistency​ and increasing compressive and flexural strength
    • Greater economy in a mix designed for a given strength, slump and air content​
    • Cost savings and increased durability

    Customers Benefit

    From test results, the addition of MasterRoc MF 505C​ to paste mix allowed for a 2% reduction in water; the optimal dose rate being 400ml per wet tonne.​ Increased flowability of the mix was demonstrated through slump results with the addition of MasterRoc MF 505CA reduction in the number of lumps within the paste occurred with the inclusion of the MasterRoc MF 505C​.​ Due to this, time savings were achieved for undercut exposures. 


    Direct contact

    Ryan Salter

    Ryan Salter

    Segment Manager Underground Construction - ANZ

    0418 222 717