Show ROA MUST BE PROPERLY PREPARED absorb and ro re lain a large amount of moisture mo lature rive give tile tip most tr trouble auble in the construction of roads these are tile the various forms forina of cly clay and a lew few of the heavier they tire anro because they hey cannot bo be drained by side aide ditches of 0 tile when frown fioren the wet soil pull expands and lifts the paver pavement nent when it dries out it often shrinks so BO materially that wide crocks cracks form setting up tensile stresses in the slab above which way may prove when tho th dried soll soil again absorbs moisture tt it expands the slab unless laboratory tests have located the rood good und and bad soils in the project tile the inspector must depend upon per 1 sonni observation alone ask those thosa who lle live along tie the rond road where the I 1 worst biota appear each spring ac company the roller and note tiny I 1 spongy places keep your eyes open I 1 for spage seepage water dog holes or short deep spon 97 spots tire arc usually caused by a pocket in an impervious underlying stratum water from sortie some higher point Is caught in this pocket and then alien ah ab sobbed by the earth above there are several methods of rem eddying bop bog holes if not too deep they may be drained by cutting through the impervious stratum and laying tile to tile bottom of the pocket when the bog hole Is formed by a rock pocket it will ivill probably be necess necessary nry to intercept the seepage water before it reaches the rond road or to remove the spongy material end and replace it with cinders sand grovel gravel or crushed stone if the spongy sell extends for soine nome distance along the roadway its ita removal would be too expensive if the other suggested courses seem seem Ini prec and it Is impossible or inadvisable to relocate the lie road the plastic material can obe be greatly improved by harrowing borrowing sand into it until a 0 inch crust Is formed this crust should be 8 10 to 0 9 10 sand sometimes a I 1 inch sand band cushion Is in placed under the slab with such euch treatment there Is little danger that the pavement will be damaged hydraulic lime or light road oil harrowed into the soil has proved beneficial in stabilizing adobe and heavy clay the light coil boll encountered in past bogs boga will support tt a pavement much as water supports a boat and need not bo be feared it will however settle under the superimposed load and at approaches pro aches of bridges should be removed und and replaced with stable soil mil near the bridge the solidity of the oil fill should be kra gradually dually reduced as the als distance tance from the bridge increases so BO that the change from firm to yielding foundation will not be too abrupt |