Formwork Requirement for No Fine Concrete

Dear reader we have discussed in previous post about compaction of no-fines concrete. Now we know much compaction effort is not required for no-fines concrete and preferably no. Thus vibration is not applied to concrete and ultimately to formwork.

Again no-fines concrete, produce low pressure on formwork. We can select a large size and lightweight forms for such concrete. Segregation is also reported negligible, which allows us to place concrete from greater dropping height.

So long and narrow vertical member like column and concrete shear wall etc. can be cast at one lift; multiple lift casting is avoided, which allow us to select large form length.

Here coarse aggregate is coated with cement paste; no slurry of cement sand is available in the system to seep or come out from leaks in the forms. For sealing leak or leak proof formwork, we have to invest both time and money.

Therefore we can use expanded metal open mesh of steel supported on light timber frames. But it is essential to ensure that forms and its bracing must have sufficient strength to support concrete without suffering deformation.

But considering economy of construction, the forms should be designed such that transportation, handling and ease of fixing are ensured having sufficient ductility and strength to use repeatedly for future project or future extension of existing project.