Crushed Granite Research Articles

A sensibility analysis of model selection in modeling the reactive transport of cesium in crushed granite

We performed a sensibility analysis of model selection in modeling the reactive transport of cesium in crushed granite through model calibration and validation. Based on some solid phase analysis data and kinetic batch experimental results, we hypothesized three two-site sorption models in the LEHGC reactive transport model to fit the breakthrough curves (BTCs) from the corresponding column experiments. The analysis of breakthrough curves shows that both the empirical two-site kinetic linear sorption model and the semi-mechanistic/semi-empirical two-site kinetic surface complexation model, regardless of their complexity, can match our experimental data fairly well under given test conditions. A numerical experiment to further compare the two models shows that they behave differently when the pore velocity is not of the same order of magnitude as our test velocities. This result indicates that further investigations to help determine a better model are needed. We suggest that a multistage column experiment, which tests over the whole range of practical flow velocities, should be conducted to help alleviate inadequate hypothesized models.

Surface and bulk sorption of uranium(VI) onto granite rock

Surface and bulk sorption of U(VI) onto granite rock with different types of surfaces were carried out and the results were compared for the different surfaces such as crushed granite, machined core granite, and core granite with fractured surface. The sorption behavior of U(VI) dependent on surface types was investigated and discussed for contacting time, pH, constituent minerals, and surface area. Results from the sorption experiments were also compared each other in order to analyze the differences in sorption behaviors of U(VI) and to correlate the surface sorption coefficient Ka and the bulk sorption coefficient Kd. The effect of contact time and pH on the sorption of U(VI) onto fractured surfaces was larger than that onto the machined fresh surfaces but smaller than that onto the crushed surfaces. As expected, it was noticed that the surface sorption coefficients of U(VI) for the natural fracture surfaces were greater than those of the machined fresh surfaces due to the higher content of secondary minerals such as calcite and chlorite which acted as stronger sorbents. It is presumed that there are many micro-fractures or micro-pores available for the uranium sorption on the granite surfaces, even on the machined fresh surfaces, and there can be an intrinsic difference between the surface and the bulk sorption due to the different types of surfaces.

Test methods for fine aggregate angularity considering resistance of rutting

The objective of this study was to compare rutting resistance of hot mix asphalt (HMA) containing fine aggregates with different angularities. Rut depths were measured using the Asphalt Pavement Analyzer (APA). HMA mixtures were designed following the Superpave specifications, to the extent possible, and prepared using the Superpave gyratory compactor. Six different mixtures were prepared using the same gradation. In all mixtures, crushed limestone was used as the coarse aggregate. Six different fine aggregates were used: crushed granite, crushed river gravel, crushed limestone, sub-rounded natural sand, blend of 85% granite with 15% natural sand, and blend of 70% limestone with 30% natural sand. Angularity of the fine aggregates was measured using Superpave fine aggregate angularity (FAA), direct shear test, compacted aggregate resistance (CAR), and VDG-40 videograder. Friction angle derived from direct shear tests and slenderness ratio from the image analysis showed good correlations with rut depth.

The influence of coarse aggregate and reinforcement on the anchorage bond strength of laterized concrete

Many factors are known to affect the anchorage bond stress of laterized concrete. Laterized concrete is concrete in which some, or all, of the fine aggregate is from lateritic soils. The effect of types of coarse aggregate and reinforcement on the anchorage bond stress of laterized concrete was investigated in this study. The punching test method was used to determine the anchorage bond stress characteristics of laterized concrete specimens cured for 28 days. The results have shown that for the crushed granite and the dug-up aggregates (“dug-up aggregate” refers to aggregates obtained from natural sources and have almost the same size range with the crushed granite), the values of anchorage bond stress obtained compare well with those of the ordinary concrete but higher than that of the lightweight concrete. The anchorage bond stress values obtained for specimens made of dug-up aggregates are higher than those obtained for crushed granite. Higher anchorage bond stress values were obtained for laterized concrete specimens containing deformed bar reinforcement than those containing plain bar reinforcement. Laterized concrete specimens having higher cement content produced higher anchorage bond stress.

The Sorption Behavior of Np on the Crushed Granite Media

The Sorption Behavior of Np on the Crushed Granite Media

Effect of Mineral Filler Type and Amount on Design and Performance of Asphalt Concrete Mixtures

Three methods for classifying aggregate particle shape and texture—AASHTO TP33, ASTM D3389, and the flow rate method—were evaluated. These methods were used to rank four natural river sands and a crushed granite from good to poor performance based on the criteria established by each method. Test results indicate that all methods easily distinguished the crushed aggregate from the natural river sands. The AASHTO TP33 and the flow rate method were found to be somewhat less sensitive to slight differences in particle shape and texture than was ASTM D3398. All the test methods were found to be repeatable, each having low coefficients of variation for all the aggregates tested. To evaluate the effect of particle shape and texture and mineral filler content on mix performance in permanent deformation, one natural sand ranked as average performing was selected and blended with the crushed granite in the proportion of 20 percent natural sand and 80 percent crushed granite. Asphalt-aggregate mixtures containing 4, 6, 8, and 12 percent mineral filler were designed by using the Marshall procedure and were tested in repeated shear test at constant height. Within the range of mineral filler type and contents used, results indicate that mixtures containing 100 percent crushed granite show lower accumulation of permanent strain than does an 80/20 blend of crushed granite and natural sand, and an increase in the mineral filler content of a mixture was found to decrease its accumulated permanent strain while increasing the mixture shear resilient modulus.

Laboratory and in situ investigation of the isotopic ratio 79Br/81Br as a tracer of water migration in crystalline rocks

The natural isotope 79Br in the bromide form was used as a hydrological tracer of groundwater movement. Laboratory-scale infiltration experiments using cylinders cored from granite and repacked columns of crushed granite showed that the change of the natural isotopic ratio 79Br/81Br with time can be used to monitor the tracer breakthrough. Comparison was made with other non-sorbing tracers, such as tritiated water, chloride and iodide. The difference in travel time of halides was suggested to be related to the solute size. A 79Br− migration experiment in crystalline rock was carried out between two boreholes connected by a low-permeability fracture. This showed the suitability of 79Br− as a groundwater tracer also for field tests.

Behavior of Some Pavement Foundation Materials Under Repeated Loading

A wide range of alternative materials for pavement construction were studied, and assessment techniques to enable and increase their use were developed. Five secondary materials and a conventional crushed granite were considered for use in an unbound form or lightly treated with various binders (including primary and secondary binders) in a total of 11 road pavement subbase materials. The secondary materials studied were minestone, china clay sand, slate waste, fly ash, and furnace bottom ash. The laboratory program set up for this research essentially was based on repeated-load triaxial tests, and the techniques used for specimen preparation, conditioning, and testing for resilient behavior are described. In particular, the modifications of the procedures recommended by the European Committee for Standardization necessary for testing secondary materials are identified and described. The analysis of the resilient behavior of the materials studied led to the identification of two groups with identical characteristics: unbound type of behavior (which included lightly treated mixtures), and treated type of behavior. A definition of boundaries for those groups was attempted. The mechanical properties of these materials necessary for use in analytical methods of pavement design are also presented, and the implications of treatment in terms of triaxial strength and resilient modulus are discussed.

Occupational exposures to fibers and quartz at 19 crushed stone mining and milling operations.

From 1979 to 1982, the National Institute for Occupational Safety and Health (NIOSH) conducted a cross-sectional exposure assessment and mortality study of selected crushed stone facilities in the United States. This study was undertaken in part to address concerns that asbestos exposures could be occurring in some crushed stone operations due to the presence of amphibole and serpentine minerals. The investigation was also designed to characterize exposures to crystalline silica and other mineral compounds. Nineteen crushed stone operations, mining limestone, granite, or traprock were surveyed to assess exposures to respirable and total dusts, mineral compounds including crystalline silica, asbestos, and mineral fibers. At the initiation of the study, crushed stone operations were selected from a Mine Safety and Health Administration (MSHA) listing of the active industry in 1978. With the exception of requiring inclusion of the traprock operation in Maryland where asbestos fibers were initially discovered, a stratified sample of operations was randomly selected by rock type (granite, limestone, traprock, or sandstone). However, because of reluctance or refusal of some companies to participate and because of the closures of some of the selected operations, replacements were randomly selected. Some replacement selections were likewise replaced due to lack of cooperation from the companies. The studied sample included only 10 of the 27 randomly selected operations in the original sample. Asbestos fibers were detected at one traprock facility, the Maryland operation where asbestos was originally found. Measured personal exposures to fibers exceeded the NIOSH Recommended Exposure Limit (REL) for two out of 10 samples. All of the samples were below the MSHA Permissible Exposure Limit (PEL), which was in effect at the time of the survey. However, due to the presence of nonasbestos mineral fibers in the environment, it could not be stated with certainty that all of the fibers counted by phase contrast microscopy were asbestos. A variety of silicate mineral fibers (other than those classified by NIOSH as asbestos) were detected in the traprock operations and at one granite operation. Crystalline silica was detected at 17 of the 19 surveyed crushed stone operations. Overexposures to crystalline silica were measured at 16 of the crushed stone operations; approximately one in seven personal-respirable dust samples (14%) exceeded the MSHA PEL for crystalline silica. Approximately 25% of the respirable dust samples exceeded the NIOSH REL for crystalline silica. Mill operators and mill laborers consistently had the highest and most frequent overexposures to crystalline silica.

Modelling the Consumption of Oxygen by Container Corrosion and Reaction with Fe(II)

AbstractA model is described that predicts the rate of O2 consumption in a sealed nuclear fuel waste disposal vault as a result of container corrosion, reaction with biotite and the oxidation of organics and other oxidizable impurities in the clay. The most important reactions leading to the consumption of O2 for Cu containers in a conceptual Canadian disposal vault are container corrosion, the oxidation of dissolved Cu(I) and the oxidation of organics and other impurities in the clay. Consumption of O2 by the oxidation of dissolved Fe(II) from biotite is significant in backfill materials containing crushed granite and in the rock itself. The O2 initially trapped in the disposal vault is predicted to be consumed in between 50 and 670 a.

The Use of Some Ion-Exchange Sorbing Tracer Cations in Insitu Experiments in High Saline Groundwaters

AbstractThe possibility to use alkali metals and alkaline earth metals as slightly sorbing tracers in in-situ sorption experiments in high saline groundwaters has been investigated. The cation exchange characteristics of granite and some fracture minerals (chlorite and calcite) have been studied using the proposed cations as tracers. The results show low Kd’s for Na, Ca and Sr (∽0.1 ml/g), while the sorption is higher for the more electropositive cations (Rb, Cs and Ba). A higher contribution of irreversible sorption can also be observed for the latter group of cations. For calcite the sorption of all the tracers, except Ca, is lower compared to the corresponding sorption to granite and chlorite. Differences in selectivity coefficients and cation exchange capacity are obtained when using different size fractions of crushed granite. The difference is even more pronounced when comparing crushed granite to intact granite.

Influence of water/cement ratios and mix proportions on workability and characteristic strength of concrete containing laterite fine aggregate

This paper examines the variation of workability and characteristic strength of laterized concrete (concrete containing laterite fine aggregate instead of sand) with different water/cement ratios and mix proportions. Four mixes of cement: lateritic soil: crushed granite were considered, namely 1:1:2, 1:1 1 2 :3, 1:2:4 and 1:3:6. Two methods—slump and compacting factor tests were used for the workability while the conventional cube test was used for the compressive strength. Cubes (100 mm) were made, water-cured at 21 + 2° C and tested at 7 and 28 days. The results showed that the water requirement for a mix increases with increase in laterite/cement ratio. Associated with slump test are: zero, true, partial collapse and collapse slumps. The strength decrease with increase in laterite/cement and water/cement ratios. It was further found that the workability decreases with increase in laterite/cement ratio. The results indicated that the well established variations of workability and compressive strength of normal concrete with water/cement ratios are valid for laterized concrete.

A Comparison of the Behaviour of Vitrified HLW in Repositories in Salt, Clay and Granite. I: Experimental

Laboratories from 11 countries participated in a ‘Round Robin’ comparative test excercise using the European Commission's Repository Systems Simulation Test [1,5]. The compulsory core part of this exercise involved testing an inactive simulant of the French high-level waste glass (SON68) in containers in which the conditions were similar to those that might occur after disposal of vitrified waste in a future repository. There were three options for the test, representing repositories in clay, granite and salt. Fifteen laboratories, mostly from within the European Community, but including laboratories from USA, Canada and Japan took part in the Round Robin. Most of the laboratories only covered one option: clay, 3, granite, 10, and salt 6. The test procedure was closely specified by the European Communities. This contribution and a companion paper [2] summarize the acquired information.The HLW borosilicate glass SON68 (R7T7), to be returned to and eventually disposed of in various geological repositories by Cogema's reprocessing customers, was tested in a stainless steel autoclave developed and provided by CEA, Marcoule. The glass was prepared and delivered by CEA; together with crushed granite, sand, smectite and groundwater for the granite option. SCK-Mol provided the clay, smectite, sand and the recipe for claywater, HMI-Berlin the recipe for the rock salt composition. The analytical method was the only variable to be chosen by the participants. After termination of the experiments (duration 14-364d, temperature 90°C), the concentrations of the glass constituents Si, B, Mo, Li, in solution had to be determined. The data base was used to evaluate the test procedure and to identify analytical problems.

Palm kernel shell as a lightweight aggregate for concrete

These concrete mixes of widely differing water/cement ratios were made using palm kernel shell as course aggregate. The properties tested include the physical properties of the shell, the compressive, flexural and tensile splitting strengths of the concrete. These properties were compared with those of similar concrete specimens made with crushed granite as course aggregate. Results of the tests suggest that palm kernel shell cannot produce concrete with compressive strength above 30 MPa. However, for concrete grade 25 and below, the material was found to compare favourably with other conventional aggregate such as crushed granite.

Static Leaching of Radioactive Glass Under Conditions Simulating a Granitic Repository for High-Level Waste: Phase 1.

ABSTRACTA joint research project with participation from Japan, Switzerland and Sweden is underway at Studsvik (The JSS-project). The project concerns investigations on the leaching of fully radioactive glass (containing 12 wt% fission product oxides and actinide oxides) manufactured by CEA/Marcoule.So far the glass has been leached in doubly distilled water and in silicate water at 90°C. Some leaching experiments involved the presence of crushed Stripa granite in the same containers as the glass.Due to strong radiation and the presence of plutonium the leaching was carried out in a specially designed lead cave using gilded stainless steel containers.Weight losses, pH and elemental mass losses were determined together with infrared reflection spectral changes. These data are compared to those obtained from a simulated nonradioactive glass of nearly the same composition and to similar alkali borosilicate glasses previously investigated at Studsvik.

Effect of varying sand content in laterized concrete

Tests are reported on concrete containing crushed granite, sharp sand and fine laterite in varying proportions. The percentage of sand by weight of the total fine aggregate was varied in steps of 25% up to a maximum of 100% corresponding to normal concrete. The standard mixes which were investigated were 1:2:4, 1:1 1 2 :3, and 1:1:2 . The compressive strengths were determined up to 84 days. The most suitable mix for structural applications was found to ben 1:1 1 2 :3 without about 0.65 water/cement ratio provided that the percentage laterite content is kept below 50%. Compressive strength of not less than 25 N/mm 2 was obtainable at 28 days for this mix with laterite content of about 25–50%. The density of laterized concrete and its compressive strengths show that laterized concrete is a dense and structurally sound material. The modulus of elasticity of the recommended mix of laterized concrete ( 1:1 1 2 :3 ) may be as high as 18–20 kN/mm 2 if the mix is well controlled.

Preliminary investigation of volume changes in crushed granite preceding stick‐slip failure

A large granite sample containing a saw‐cut filled with crushed granite, modeling a natural fault with gouge, was loaded triaxially at confining pressure of 400 MPa. Changes in pore volume of the simulated gouge layer were measured during application of confining pressure and during axial loading to failure by sudden stick‐slip. Pore volume strain in this configuration, with a thin layer of gouge between rock surfaces, was significantly less with increasing confining pressure than in similar experiments in which the entire sample was of crushed granite. Our sample continued to decrease in volume upon application of axial load up to the point at which sliding on the saw‐cut started. At this point, the decrease in volume slowed down, and the volume increased just before failure. Failure occurred at a stress below that required to cause dilatancy in intact rock, suggesting that gouge might show premonitory changes before earthquakes that would not appear in intact rock surrounding a fault zone.

Mechanical Scarification of Dormant Wild Rice Seed1

AbstractWild rice (Zizania aquatica L.), which formerly grew only under natural conditions until the early 1960's, is now being grown as a cultivated field crop. A 3 to 6‐month, post‐harvest seed dormancy hinders the continued development of wild rice as a field crop. Part of this dormancy is due to an impermeable pericarp. Scarification with chemicals to increase permeability has not been successful, and scraping the individual seeds to remove the pericarp above the embryo is too time‐consuming. A small rock polisher was evaluated as a scarification device in this study. Three dehulled seed lots, one from greenhouse‐grown plants and two from field‐grown plants with different harvest dates were used. Samples from each were tumbled with dry crushed granite in the polisher for varying times or scraped with a razor blade to remove the pericarp above the embryo. Laboratory and greenhouse gemination were used to measure the resulting release of dormancy. Seed tumbled in the laboratory for 1 hour gave gemination percentages in water of 44 to 60, depending on the seed lot. Scraped seed gave gemination percentages of 65 to 100 for the corresponding seed lots. Tumbling resulted in less seed injury and required less time than scraping seed. Placing tumbled or scraped seed 1.5 cm deep into soil in the greenhouse before flooding gave an average gemination percentage of only 13 compared to 64 when seed was germinated in water. Transplanting seedlings from scarified seeds germinated in water was more successful than direct planting of scarified seed to establish greenhouse stands. Use of the rock polisher significantly accelerated scarifying wild rice seed with a minimum amount of injury. This method may be adapted to other high moisture seed that requires scarification.

A note on the effect of fault gouge composition on the stability of frictional sliding

The frictional properties of fault gouge have been studied at confining pressures to 6 kbars. If the gouge is composed of strong materials such as crushed granite or quartz sand, the frictional strength is high, and violent stick-slip occurs at confining pressures above approximately 1.5 kbars. If the gouge is composed of minerals such as illite, kaolinite, chlorite, or antigorite, which have weak bonding forces between the structural layers, the frictional strength is slightly lower, but violent stick-slip still occurs under high confining pressure. The expanding clays, montmorillonite and vermiculite, which have free water between their structural layers, slide stably at confining pressures as high as 6.25 kbars and exhibit low friction. A similar stable behavior with lowered strength is observed in water-saturated quartz sand when the water is confined within the fault zone during deformation. The results of this series of experiments support water being the stabilizing influence when it is either (1) trapped within or between rocks of low permeability and can provide a high pore pressure when the rocks are deformed, or (2) loosely bonded in a mineral structure, as in the hydrated clays, where it can produce a pseudo-pore pressure when the clay is compressed. In both these cases, the effective stress can be reduced and the deformation stabilized.

Note on the deformational behaviour and permeability of crushed granite : Zoback M D; Byerlee, J D Int J Rock Mech Min Sci Geomech Abstr, V13, N10, Oct 1976, P291–294

Note on the deformational behaviour and permeability of crushed granite : Zoback M D; Byerlee, J D Int J Rock Mech Min Sci Geomech Abstr, V13, N10, Oct 1976, P291–294