Steel fiber was introduced to Japan about 40 years ago. Characteristics of steel fiber are substantially affected by the manufacturing method. Therefore, first of all, manufacturing methods of steel fibers are described.
The next place, characteristics of steel fiber reinforced concrete (SFRC) are shortly reviewed. It is well known that concrete or mortar is one of the fragile materials that possess low tensile strength and relatively high compressive strength. The addition of steel fibers randomly distributed in the matrix, substantially improves their mechanical performance such as residual strength in compression, strength/toughness (energy required up to failure) in bending, impact strength, fatigue strength and also wear resistance.
In the past 40 years, SFRC had been gaining various application fields. In the final part of this report, main application fields of SFRC are picked up and shortly explained. For example, SFRC was used for tunnel support, dam site, river facilities, road pavement and floor in building. In most application fields, SFRC has obtained excellent reputations by virtue of its durability under severe physical and environmental conditions.
Many researches concerning steel fiber and SFRC are now undergoing and SFRC is still gaining new application fields.

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Stress measurements may give us only local stresses, which are affected by heterogeneity of rock mass, discontinuities and surface topography. Therefore, it is necessary to determine regional stress from limited data of local stress for estimating stress distributions in a region under consideration for various engineering projects such as underground repository of high-level radioactive wastes.
In this study, regional stress in a rock mass with a penetrating fault was defined as displacements at the boundaries as a function of the coordinates, which are different for the upper and lower rock bodies to allow relative displacements of the fault. The fault was modeled by joint elements with 16 nodes, and a condition for frictional sliding was given by Coulomb' s criterion. First, by using a small-scale model having a fault, the effects of frictional sliding of the fault on the distributions of both stress in the rock mass and the shear stiffness of the fault were investigated. Next, based on the results, we proposed a method for determining regional stress with a 3-D finite element method from stress data measured along a line that penetrates the fault. It was shown that the stress distribution in a region under consideration can be estimated by the method when a sliding area of the fault is less than half of the whole area, although the estimation becomes poorer as the sliding area increases.

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A tensile strength deduced from a hydraulic fracturing stress measurement is different from tensile strengths obtained by a Brazilian test and by a bending test. In this paper, the authors discussed the differences based on a probability theory of fracture considering stress distribution in the specimen. At the first, they conducted the three tests in specimens of Kurokami-jima granite, and suppose that variation of their tensile strengths follows Weibull distribution. At the second, from ratios of tensile strengths among the hydraulic fracturing, the Brazilian test and the bending test, they found that Weibull's coefficient of uniformity, m, equals to 10.1. At the third, they elucidated that the obtained coefficient of uniformity is good for a significance level in the Kolmogorov-Smirnov test.
Through the discussion, it is concluded that the differences of the tensile strengths among the hydraulic fracturing, the Brazilian test and the bending test can be explained to some extent by the probability theory of fracture.

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Most rocks indicate some extent of visco-elastic properties or time dependency. For example, strength and Young's modulus increase with loading rate in uniaxial compression test. In creep test, strain increases with time though stress is maintained to be a predetermined value. This visco-elastic behaviour is especially notable in porous rocks such as tuff or weathered rocks.
In this study, visco-elastic properties of porous rocks are shortly reviewed and a new physical model or a constitutive equation is proposed. The model consists of a spring and a dashpot. It is assumed that the constitutive equation formerly proposed by these authors can be applied to the spring. Viscosity of the dashpot is quite low before loading, and is increasing gradually with progress of loading. In creep testing at low stress level, strain of the dashpot corresponds to creep strain because the spring constant does not decrease meaningfully at the low stress level.
The experimental results of muddy sandstone, Oya tuff, Tage tuff and Kawazu tuff were compared with the calculated results. It is found that stress-strain curve shows good coincidence between experimental and calculated results. Increase of strength and Young's modulus with loading rate is well simulated by the model. Most important results are that, even at low stress, strain of the dashpot is considerably larger than formerly considered. By this model, the difference of Young's moduli between air-dried and water saturated conditions is well simulated where the difference in Young's modulus is assumed to be the deference in strain of the dashpot. In water-saturated condition, strain of the dashpot increases more rapidly and then Young's modulus is relatively small.

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Life Cycle Assessment (LCA) has been widely applied to evaluate environmental impacts regarding production and service activities. In a preparation stage for LCA, a catalog called Life Cycle Inventory (LCI) should be developed, summing up resources inputs, outputs and environmental burdens. However, in most of LCI studies, mining activities are excluded from their system boundary because of the difficulty in data acquisition from foreign mine sites especially for Japan. Systematic LCI on mining activities is needed for more accurate LCA.
In this paper, a database to estimate LCI on the mining and mineral processing activities is constructed using the cost functions of CES(Cost Estimating System, USBM). This database called MLED (Mining LCI Estimating Database) provides standard CO₂ emission level for each production style on mining and beneficiating process. MLED with data input-output interfaces automatically calculates CO₂ emissions as well as consumptions of energy and materials.
Two case studies are carried out using MLED. One is for an underground copper mine in South America. CO₂ emissions for various production rates and mining methods have been estimated to compare with the present mining process on this site. In the second case study, CO₂ emissions in a large scale surface mine in Chile have been estimated and compared with actual data of this mine to verify the validity of MLED.
Considering the recent situation in environmental regulations, inventory estimating model such as MLED will become one of the useful tools to estimate the environmental burdens and improve the mining design.

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Jarosite (KFe₃(SO₄)₂(OH)₆) is a secondary mineral in acidic polluted environments such as mine tailing dump, but few investigations have evaluated arsenic removal by jarosite.
This study investigated the role of jarosite in arsenic removal using flask shaking experiments in diluted sulfuric acid solutions (pH1-3). Jarosite was synthesized and the chemical composition of the jarosite was K_0.54(H₃O)_0.46Fe_2.38(SO₄)₂(OH)₆. The shaking experiments found that As(V) was removed by the jarosite but As(III) was not removed. The mechanisms of As(V) removal were adsorption on the jarosite and co-precipitation with Fe(III) extracted from jarosite. The removal of As(V) from the liquid phase were increased with increasing pH, indicating that the adsorption of As(V) and SO₄^2- is competitive or that ionic As species (H₂AsO₄^-) is selectively adsorbed. The results suggest that jarosite is a sink for As(V) in acidic polluted environments.

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The extraction of zinc and cadmium from aqueous solutions by long-chain alkyl quaternary ammonium carboxylates, prepared by combination of trioctylmethylammonium chloride (R₃R'NCl) and carboxylic (octanoic, decanoic and lauric) acids (R"COOH), in benzene has been investigated in the vicinity of neutral pH. The organic phases were examined by infrared spectral measurements. As a result, it is found that the extraction efficiency is in the order Zn ‹Cd and Zn› Cd with R₃R'NR"COO concentrations which are higher or lower than 0.05 mol dm^-3, respectively. In addition, the extraction processes for Zn(II) and Cd (II) may be expressed as Zn²⁺(aq) + 2Cl^-(aq) + 3R₃R'NR"COO(org)↔(R₃R'N) [Zn (R"COO)₃] (org) + 2R₃R'NCl(org) and CdCl⁺(aq) + Cl^-(aq) + 2R₃R'NR"COO (org)↔(R₃R'N)₂[Cd(R"COO)₂Cl₂] (org), respectively.

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