The Workshop.

Otago Witness, Issue 1243, 25 September 1875, Page 3

The Workshop.

CONCBETE FOUNDATIONS. The following remarks by E. Dobson, C.E., author of Weale's Treatise on Foundations, are worthy of attention : " It may fairly be questioned, whether a gTeat proportion of the concrete foundations in this country made with chalk lime, or with very weak water limes, do not act by transmitting the pressure of the structures laid on them against the the sides of the foundation- pits rather than by their resistance to cross strain, although they may in time become thoroughly consolidated. Our own experi-

ence leads us to feel that, unless the lime used in the composition of concretes is soon, as to ensure the formation of a mass which shall at once become firm and solid throughout, it will be better, under ordinary circumstances, to use the gravel in a loose state, merely punning it to force it thoroughly into the aides of the trenches. If this view is correct, much expense is often incurred in making bad concrete, where a layer of broken stone or gravel, would be cheaper and more effective ; and would especially recommend those of our readers who may have opportunities of examining concrete foundations which have been only a short time executed, to do so with especial reference to this point, which is of consieerable importance. The most prudent course, in putting in a concrete foundation, is always to force the concrete into the trenches, ramming it continually, so that it shall exert considerable lateral pressure.