Crushed basalt

Research carried out by Nikolaides and Manthos (2007) on aggregates derived from various rocks (limestones, gabbros, basalts, crushed sand-gravel and steel slags) found that the sand equivalent values determined in accordance with the European standard (SE0/2) were always lower than those determined in accordance with the American standard (SEo/4.75). The results obtained are shown in Figure 2.1. 

Millbillillie regolith breccia, in plane-polarized light, 2 cm across. Clasts of basaltic eucrite are visible in a crushed matrix, crosscut by a vein of shock-melted material. Image from Lauretta and Killgore (2005), with permission. 

Gillman, G.P. 1980. The effect of crushed basalt scoria on the cation exchange properties of a highly weathered soil. Soil Science Society of America Journal 44 465-468. 

Since crushed basalt has been recommended as a major backfill component (1), experiments were completed to evaluate the rate of dissolved oxygen consumption and the redox conditions that develop in basalt-water systems under conditions similar to those expected in the near-field environment of a waste package. Two approaches to this problem were used in this study (l)the As(III)/As(V) redox couple as an indirect method of monitoring Eh and (2) the measurement of dissolved oxygen levels in solutions from hydrothermal experiments as a function of time. The first approach involves oxidation state determinations on trace levels of arsenic in solution (4-5) and provides an estimate of redox conditions over restricted intervals of time, depending on reaction rates and sensitivities of the analyses. The arsenic oxidation state approach also provides data at conditions that are more reducing than in solutions with detectable levels of dissolved oxygen. 

Sample Preparation. The basalt was crushed and sieved, and the -120 + 230 mesh fraction was used. The grains were ultrasoni-cally washed in deionized water to remove very fine adhering particles. If these particles are not removed, they will preferentially dissolve under hydrothermal conditions, resulting in abnormally high rates of mineral-fluid reactions (10). Examination of samples of the basalt on a scanning electron microscope assured that all fines had been removed. Nitrogen B.E.T. specific surface area of the washed basalt was 2.7 m2/g. 

Applications. In the following paragraphs, the conditions (temperature, time, water/rock mass ratio, surface area) and the results on closed system oxygen consumption and redox conditions of the basalt-water experiments are compared to expected conditions in the open system backfill and near-field environment of an NWRB. Crushing of basalt for pneumatically emplaced backfill could result in a substantial fraction of finegrained basalt with a variety of active surface sites for reaction similar to the crushed basalt used in the experiments. The effects of crushing on rates of mineral-fluid reactions are well documented (10,26). 

With the addition of bentonite to a crushed basalt backfill, aqueous diffusion would be the most effective mass transfer process (31). Aagaard and Helgeson (32) state that at temperatures <200°C, aqueous diffusion rates are orders of magnitude greater than rates of silicate hydrolysis even in acid solutions. Therefore, the dissolution rate of backfill phases and the overall mass transfer process could be controlled by reactions at the mineral-fluid interface. As stated earlier, dissolution of basalt phases in the sampling autoclave experiments may also be controlled by interface reactions. 

An auxiliary experiment, performed at 90°C with ground-water and a column of crushed basalt chips and with a basalt surface area to groundwater volume ratio equivalent to that of the analog basalt fissure (2 x 10 cm" ), has elucidated this phenomenon Data from this experiment, which are presented in Figure 3, show that the sodium-ion concentration of the ground-water does not decrease gradually from its initial value of... 

Materials Used. The sulfur used was obtained from the refinery and was 99.9% pure. As for the grain form, gravel as spherical material and crushed stone (granulit, basalt) as sharp grain material were used as aggregates. In mineral composition, granulit is an acidic rock, but basalt, on the other hand, consists mainly of basic mineral components. 

Hydrogen gas is sometimes naturally found in geological structures recently, crushed basalt and H20 in the dark under anaerobic conditions was found to generate H2. This would account for natural emissions and explain the energy source for bacteria growing in underground systems.3... 

The raw basalt is mined, crushed, and melted at 2300°F (1250°C) and poured into sand or iron molds. The solidified material is placed in the annealing furnace, where temperature is raised and lowered in a specific range, for up to two days to achieve a uniform and fine crystalline structure. This gives the material its extreme hardness and resistance. 

High-Temperature Processes. Silicate Melt Process. One of the high-temperature processes we are studying involves simple melting of a mixture of salt cake with either crushed basalt rock and B2O3 or sand... 

Crushed basalt core from Well S-4 at 0.3 m below surface at Box Canyon near Idaho National Laboratory (INL). 

The lower diatreme contains an unstratified mixture of crushed country rock, basalt clasts, and blocks of strat-ihed rim-tuff as well as basalt dikes that originated in the root zone. The upper part of the diatreme features a shallow maar crater that is partially hlled with well-bedded post-eruptive sediment including pyroclastic rocks. 

Aggregate Basalt 0/1 Crushed brick Fireclay 0/1 Corund 0/1 Crushed glass ... 

Table 2. Percentage of glass and clay in samples of crushed basalt.

The relationship between expansion and the content of clays and volcanic glass was studied in a previous work (Rocco et al. 2012). To this end, samples of crushed basalt impregnated in epoxy resins were used to obtain a representative sample of the aggregate processed at the quarry. 

Basalt and diabase (crushed) Concrete aggregate, railroad ballast, and roofing granules. 

Fusion-cast Basalt. An abrasion-resistant material made by fusing natural basalt and casting the molten material into moulds to form blocks. The hardness is 8-9 Mohs crushing strength, 500 MNm-2. These blocks can be used for industrial flooring and for the lining of bunkers, chutes, and other equipment where abrasion is severe. 

The specimens were cast with concretes made with three kinds of coarse aggregate crushed basalt, river gravel and crushed limestone. Other specimens were prepared with cement mortar and paste. The specimens were subjected to shearing as shown in Figure 10.38. 

Figure 13.9 shows the arrangement of a solar dryer with rock-bed storage [20]. The dryer is a direct system the collectors 1 are located on the ground and have an area of 193 m. The air warmed in the collectors is forwarded into drying space 3 by a fan 2. The dryer has room for a maximum of 6.5 m timber 4. In the upper roof space two ventilators are placed that are used for continuous circulation of the air. Vents 6 are placed in the sidewalls of the roof space for allowing inflow and outflow of air. The rock bed 7 is about 22 tons of 19-mm crushed basalt. The dryer operates as follows. 

Cast Basalt is also used in various high erosion situations. This is a volcanic rock that has been crushed and cast at about 1250°C, either in moulds or by centrifuging, to obtain the desired shape, and then given a special heat treatment where it recrystallizes into a very hard material (720 Vickers, 8-9 on the Mohs scale). It is used to protect pipes, cyclones and other equipment from erosive attack. 

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