Rammers

Rammed earth needs a few things to make sure it works, and one of them is a good rammer. However this has not prevented a wide range of rammers being highly effective with materials typically being wood, metal and stone. In Hungary there were apparently traditional ramming clogs which seems very logical but finding an image of them has proved difficult.

In the UK until recently there was a round headed metal rammer available until reasonably recently but most available are square. A square rammer fits nicely into a square formwork, but does not work well with a chamfered or rounded corner, more normal for rammed earth work.

Many ramming cultures have more than one tool, typically one for edges and one for general ramming, although there are many places that don't. The three main factors which allow the successful ramming of earth from the point of view of the rammer are:

• the surface area of the rammer head

• the thickness or depth of earth to be rammed

• the force of the rammer

The surface area of the rammer head can be bigger where the thickness or depth of fill is shallower. A wacker plate could work but the depth of fill of each layer would be very shallow. Thin

headed rammers are used around the edge of the formwork to produce a hard surface finish while the mass of the wall is rammed done with a bigger head.

The weight of rammers also varies and this reflects differences in opinion amongst the people that use them. Some prefer a heavier 'lift and drop' type rammer, while others prefer a lighter tool which they can power themselves.

Handles tend to be of timber although metal pipes can also work. Wood is preferable in areas where lightening is a problem.

There are also mechanical rammers, typically pneumatic, which need a compressor to work. There are also petrol driven and small electric rammers. The main thing about what rammer is chosen is that it must be flexible enough to use in formwork. Or the formwork needs to be simple enough to use the tool. Where formwork has bolts though the tool has to be repeatedly lifted over the bolts to access all the areas to be rammed. Petrol rammers may be effective but they also tend to be heavy, too heavy for one person to repeatedly lift. Other options include sheeps foot rollers but again they require formwork with no bolts and the ability to crane them in and out at the end of the build.

Pros and cons

Although pneumatic rammers work very well, and with cooking oil in the compressor you can reduce the emissions to an almost negligible level the decision to use them must always be economic. Where labour is cheap and people need jobs replacing people with machines rarely makes sense. Once you have shown someone mechanical ramming they will always favour it, believing that it saves them energy and increases build speed. But when you have held a pneumatic tool for a few days you quickly realise how much hard work it really is.

In contrast a well organised hand ramming team  can produce a lot of work and talk and sing at the same time. This is something which rarely happens when mechanically ramming as the team tends to be smaller and the noise too much to compete with.

Hopefully looking at some of these tools will be a bit of inspiration to potential builders.