Editors' Note. The use of stone in concreting gravity dams saves cement and, as the authors of the following article show, reduces costs. However, it seems to lead to an increased expenditure of labor, and therefore the use of stone must be carefully assessed with allowance for all technicoeconomic indices. Speciai mechanization must, of course, be developed for Iaying large stones in concrete.At the present time the cost of cement is known to constitute about 40% of the cost of a concrete mixture with 250 kg per m 3 of concrete. Furthermore, the high consumption of cement in large concrete blocks (the block volume of the Ust-Ilim dam is 400-800 m 3) leads to a marked rise in temperature in the laid mass owing to emission and accumulation of heat by the hydration reaction.An effective way of reducing cement consumption is to increase the size of the filler fragments, The addition of good-quality stone (with homogeneous structure, monolithic, with rough, clean surfaces) to the concrete mixture produces a stone-concrete material with some physicomechanieal properties which are better than those of ordinary concrete [1]. tn Soviet hydrotechnicaI construction practice we already have some experience in the use of coarse stone in concrete mixes (at the Bukhtarma and Bratsk hydroelectric stations). Monitoring of the quality of the stoneconcrete placed at the Bratsk station revealed that the main characteristics of stone-cement are much better than those of the concrete which was envisaged in the plan for the zone of the dam in which coarse stone rubble was used [2].At present no studies have been made of the influence of stone, larger than the largest filler, on the limiting tensile strength of the concrete, which is a criterion of its thermal cracking resistance. A few laboratory investigations have revealed that increase in the filler fragment size reduces the tensile strength and limiting tension resistance of the concrete [3]. There are grounds for believing that the crack distribution in blocks of stone-concrete is quite different from that in ordinary concrete. The propagation of cracks, once they have developed, is governed by the distance between the stones and the formation of cracks right through the material is therefore less probable. This suggestion needs verification by field observations of cracking in stone-concrete blocks.The Technology Used for Laying Large Stones in the Construction of the Ust'-Ilim Dam. In 1970-1971 it was decided to incorporate 2.5-3 m 3 of diabase stone, obtained during preparation of the foundation pit for the generator room and from quarries, in each block of the interior zone of the dam. The surfaces of the stones were carefully freed from dirt and loose film; cracked stones were rejected. During the summer, the stones were cooled with water before being placed in the block.The blocks in which the stones were laid were at least 3 m high. To preserve the cooling coils mounted on the concrete base, the stones were laid in the second layer of the concrete mix, i.e., 70-80 cm from ...