Project: Machynlleth Railway Bridge Arch Reopening
Product: Shotcrete 430F
Main Contractor: Alun Griffiths Ltd
Specialist Contractor: Shotcrete Services
Client: Welsh Government

Natural Cement’s Shotcrete 430F was successfully used in a railway arch shotcrete repair at Machynlleth Railway Bridge, where a previously blocked arch was reopened to provide a safe route for pedestrians and cyclists.

Around 250m² of existing tunnel infill was excavated, with Shotcrete 430F applied by the specialist subcontractor, Shotcrete Services, to reinforce the structure.

Shotcrete 430F sets quickly and gains strength rapidly, therefore it suits time-sensitive work and short possession periods. Moreover, its ultra-low rebound rate—under 5%—minimises wastage, reducing both costs and environmental impact. In addition, Shotcrete 430F contains no chemical additives and uses a Natural Cement binder. As a result, any excess product or packaging is not classed as contaminated waste.

Furthermore, the 430F mix includes steel fibres, which improve structural strength without affecting its natural formulation. This feature was especially important for maintaining the arch’s integrity beneath an active roadway.

To meet Network Rail specifications, Shotcrete 430F was used alongside RamArch and additional rebar. Notably, the rebar was supplied by Innovative Support Systems Ltd, another Barnsley-based business. Together, this combination enabled the structure to achieve the required 20MPa strength. Consequently, the line could safely reopen and the site was demobilised before the blockade expired.