As the country’s leading concrete pump hire company, Camfaud is regularly called upon to carry out concrete pumping trials to aid the development of new materials. Recently we were engaged to pump a slab being constructed using Cemfree, an award-winning new concrete. Cemfree is a zero cement, structural concrete, that is being actively developed by the David Ball Group.
Pumping trials – Cemfree concrete
In Cemfree, the Portland cement is replaced by a combination of ground blast furnace slag aka GGBS (approximately 95% ) and the Cemfree activator (approximately 5%). The main selling point of Cemfree is that it is an ultra-low carbon alternative to concrete mixes that traditionally use Portland cement. The embodied CO2 of a typical CEM I structural concrete mix is approximately 350kg/m3 whereas the embodied CO2 for a typical Cemfree mix is around 50kg/m3.
In addition to its low carbon credentials, Cemfree has increased resistance to acid, is stronger and more durable than CEM 1 concrete mixes, needs less steel reinforcement and is sulphate and chloride resistant. The material for the pumping trials was produced, under the supervision of Cemfree’s technicians, by Hanson Concrete at the local Hanson plant.
The mix supplied was a relatively low slump mix, specified to ensure strength and durability in the exposed, outdoor slab. Despite not being a very flowing mix, the Cemfree concrete pumped very easily. The concrete pipeline pressures were low but this was expected as we were pumping “off the boom” using a small, 20-metre concrete boom pump.
Once the slab had been completed and the day evaluated, the trials were considered to have been a success. The batching process was routine, the material was pumped easily and the concreting subcontractor, Formwork Solutions (UK) Ltd, found the material easy to lay and obtain the required finish.
M20 pump pumping Cemfree concrete