Stone Aggregate Research Articles

Engineering-geologic conditions of the Saratovsk hydroelectric plant

1. The experience with the engineering-geologic investigations at the Saratovsk hydroelectric plant indicates that when the pits were excavated in the dense native clays, there was a decompression process with an intensity which was directly proportional to the period of existence of the pit. The decompression was caused by a sharp deterioration of the strength properties of the material, and was conducive to quick weathering of the clay. 2. At the Saratovsk hydroelectric plant as well as at many other hydraulic developments on valley rivers, there was a considerable reduction of the effectiveness of the water-lowering system around the pit, owing to clogging of the filters with ferrous deposits. This phenomenon may be avoided by using special types of filters and by adopting a certain regimen of operation of the system. 3. The difficulties with the supply of stone and concrete aggregates in the Lower Volga area may be surmounted by exploiting, in a selective manner, the deposits of comparatively weak rock, and by washing the silty particles from the fine alluvial sands obtained from the existing quarries.

Environmental Restrictions on Mineral Resource Development in Rockies: ABSTRACT

Exploration geologists, though by nature unbounded optimists, might profit by a realistic investigation of the factors which may constrict future mineral resource development in the Rockies. The two major factors which adversely affect present and future development of each mineral in a different manner are land availability and the additional cost factors for environmental protection. The amount of land available for mineral exploration and development will be curtailed substantially by present and future land withdrawals, highways, and growing urbanization. In Montana, Idaho, Wyoming, Utah, Colorado, New Mexico, and Arizona, specific land withdrawals prohibit or seriously curtail mineral development. The present wilderness area encompasses 9,996,000 acres with more being proposed at each hearing. National Park and Monument lands contain 6,446,000 acres with additions proposed at several places. The Department of Defense controls 10,066,000 acres. Additional scenic and other mineral withdrawals are being proposed with increasing frequency. Highway right-of-ways have little effect on oil exploration, but prohibit all open pit mineral extraction and can s riously affect underground mining. In Colorado, for example, 787,000 acres are covered by public roads. Each mile of interstate highway system utilizes approximately 40 acres of land surface. Growing urbanization, though not a problem everywhere, definitely curtails mineral development in some areas. It specifically affects sand and gravel, stone aggregate, and industrial minerals. The mounting concern for the mineral industries' real and fancied degradation of our environment is creating a proliferation of new laws and regulations. Each of End_Page 540------------------------------ these adds an incremental cost to mineral exploration and development. Water pollution control forces deeper surface casing, pit linings, liquid effluent treatment, and surface-water diversion around many mineral operations. Land restoration includes land leveling, erosion protection, and revegetation. Refuse or tailings disposal, likewise, may require expensive treatment facilities, extensive materials handling, stabilization techniques, and permanent revegetation. Air pollution control may require dust control, stack devices, and prevent the burning of waste. Operators not only face physical problems, but must also consider aesthetics from the viewpoint of ardent environmentalists. The Environmental Quality Act of 1969 can be invoked for any significant operation that affects fede al lands or agencies. As an example of state control, Wyoming has prepared a 99-page booklet listing its environmental control laws. Determining which state or federal law or regulation applies can be difficult in itself. The mineral industry faces not only the expenses of meeting minimum statutory requirements, but most enlightened operators face even greater costs in their voluntary efforts to be good citizens. Public hearings and citizen-sponsored lawsuits challenging any operation with significant, real or imagined, environmental impact will increase. Without extensive effort to understand and plan for future problems of land availability and the costs of environmental protection, those problems will limit seriously Rocky Mountain mineral potential. End_of_Article - Last_Page 541------------

Important agents of weathering for building and monumental stone

The atmosphere has little corrosive effect on stone without the presence of water. Washout of aggressive ingredients from the atmosphere by rainwater, however, increases corrosion and solution of stone. Dissolved CO 2, SO 2, SO 3, and Cl are the most effective corrodents. The urban atmosphere supplied much more CO 2 and sulfates through the combustion of fossil fuels than the atmosphere of rural areas; this accelerates stone decay in urban areas very much. Water with few ions in solution may be as corrosive as CO 2 and SO 4 charged water, as it is active to reach the equilibrium condition with the stone in contact. Silicate rocks can resist exposure to rainwater successfully for a long time. Exposure of facing stone and concrete aggregate to soft or acid running water or lake waters causes damage primarily to carbonate rocks. Resistant silicate rocks should be selected. Primitive animals and plants may inhabit bare stone surfaces paving the way to more extensive destruction through the production of organic acids along the root system. All rocks are subject to attack by low animals. Boring sponges, sea shells, and sea urchins may develop a dense network of pock marks near the waterline in different rock types; occasionally also in concrete.

1024 鉄骨鉄筋砕石および軽石コンクリートの材料施工法に関する研究 : 主として付着における鉄筋とコンクリートの相対変位について(材料・施工)

1024 鉄骨鉄筋砕石および軽石コンクリートの材料施工法に関する研究 : 主として付着における鉄筋とコンクリートの相対変位について(材料・施工)

119 鉄骨鉄筋砕石及び軽石コンクリートの材料施工法に関する研究 : 主として,鉄筋継手重ね長さと定着について(材料・施工)

119 鉄骨鉄筋砕石及び軽石コンクリートの材料施工法に関する研究 : 主として,鉄筋継手重ね長さと定着について(材料・施工)