Show CONCRETE BATTERY foundations F E perkins in cement age the accompanying illustration shows a concrete foundation in connection with a 20 stamp mill in a mexican mill in some cases the stamp mortar instead of being mounted directly upon the concrete block is mounted upon a casting which is called the sub base this has the advantage of spreading the mortar is made very heavy and thick also larger area than is found possible with the standard base cast integral with the stamp mortar the accompanying illustration shows the concrete mortar block in connection with stamp mortar mounted directly upon the concrete it will be noted that the base of mortar is made very heavy and thick also wider than the base of stamp mortar when used in connection with a wood mortar block the width of the base of the standard mortar when used in connection with a mortar block is usually 2 ft 4 in whereas in the case of the stamp mortar in which the mortar is mounted directly on the concrete mortar block the width of the base is 3 ft 4 in the advantage of the is in increasing the bearing dreabon aremon the concrete to a width of 4 ft and in addition the added weight of the makes a heavy mortar with which it becomes possible to greatly increase the crushing capacity due to th the e greater weight of the anvil it is customary to place packing rubber about one fourth inch thick between the cast iron base of the mortar and the upper surface of the concrete mortar block not for the purpose of making a cushion io n but rather to correct the irregularities of the surface of the concrete mortar block the bottom of the mortar as well as the bottom surface of the sub base are both machine finished and the top of the concrete mortar block should be made as smooth as possible the proportions of material used in the construction of these concrete mortar blocks is as follows one part by volume portland cement three parts by volume freshly screened sharp sand five parts by volume freshly broken rock of any suitable character for concrete work material to pass three inch diameter ring this proportion is continued to a point within two feet of the upper surface of the concrete mortar block when it will be well to change the proportions of the material as follows one part by volume portland cement two parts by volume freshly screened bened sharp sand four parts by volume freshly broken rock passing one and one half inch diameter ring the upper layer of six inches from the top surface of the concrete mortar block should be constructed with the following proper eions of materials one part by volume portland cement one part by volume freshly screened sharp sand the upper surface should be level and finished as smoothly as possible to give a true surface so that the stamp mortar or sub base may be mounted directly upon this surface requiring only the one fourth inch rubber packing to make a perfect joint grouting should not be used in placing the mortars in position for such a thin layer of cement would be gradually broken from the impact of the stamps the foundation rods are shown in the drawing with pockets for removal bof the nuts on the lower ends of the rods in case of breakage in some cases separate mortar blocks are used for each 10 stamp battery or in some of the mills a solid concrete block has been built under the entire stamps or ten batteries of ten stamps each without any expansion 3 joints eints whatever and after several years service the concrete block appears to be in perfect condition |