One meter cubic porous slag blocks were produced by carbonation of steelmaking slag with the optimum amount of water, and forcibly supplying CO₂ deep into the inner part of the block. While the carbonation reaction has been known for years, it has been difficult to achieve a uniform reaction throughout the block, restricting the size of the manufactured block. Using these new conditions, the carbonation reaction occurred homogeneously throughout the blocks. The compressive strength and bulk density of each block were 19 N/mm² and 2. 4 g/cm³, respectively. When left exposed to various weather conditions in sea water and in the atmosphere for two years, the blocks showed no cracks or destruction. The development of the blocks has great potential to solve the utilization of slag, for example by providing carbonated large blocks for use in artificial reefs and marine plant cultivating beds, and could also prove helpful in inhibiting the greenhouse effect caused by CO₂. This paper overviews the carbonation reaction and the new process for producing large slag blocks, and discusses their utilization by considering research conducted in past and recent years.

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As a method of capping specimens for the compression strength test of concrete, the unbonded capping has been standardized and now is spreading for the test. The authors intend here to provide information necessary for obtaining more concrete compression test results while saving the labor for the capping work by taking advantage of this unbonded capping, that is, to offer useful data on dimensional designing of the devices used for the unbonded capping, and the scope of applications, significance of the introduction, testing procedures, and cautions for safekeeping of the unbonded capping system.

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Super plasticizers have been increased to use in mortar and concrete in order to improve workability of those, without injuring other properties, for example, high fluidity concrete and grouting mortar. And many studies have been researched on the effect of ground blast furnace slag on improving workability of concrete incorporated using super placit isizer. This paper deals with the influence of application of ground blast furnace slag on flowability of high fluidity mortar and grouting materials, and trys to analysis the rheology of high fluidity mortar.

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[in Japanese]

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Corrosion behavior in reinforcement steel in mortar with varying small metal piece content was investigated through immersion testing in 3%NaCl for 363 days. Rusted area of the reinforcement steel after immersion testing, which correlated well with corrosion rate obtained by electrochemical impedance spectroscopy, decreased as steel fiber content increased. Moreover steel powder addition could also prove effective in decreasing the corrosion rate of the reinforcement steel. It was thought that its corrosion prevention was probably due to the consumption of dissolved oxygen in concrete due to small metal piece corrosion.

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