Small-sized core method by sodium gluconate can be used in determining the unit cement content of concrete.Applicability of this method to quality control of concrete in structures was examined.A full-scale model structure with a high fluidity concrete, whose extent of segregation was intentionally increased, were built and relationship between concrete quality and the unit cement content determined with the small-sized core method by sodium gluconate was studied.It was shown that the relationship was correlative and application of small-sized core method by sodium gluconate to the quality control of concrete in structures was found to be reasonable.

The JIS A 1119, testing method of differences in mortar and coarse aggregate content in concrete mixed with a concrete mixer, has been used as a mixing performance test of mixers. In this paper, applicability of JIS A-1119 to high-strength and high-fluidity concretes is examined taking into account other mixing performance tests such as JIS A 5308 and JIS A 8603. High-strength and high-fluidity concretes, with various cement types and water-cement ratios, were mixed with a full-scale mixer under summer, normal and winter conditions. Differences in unit mass of mortar and unit coarse aggregate content in the concrete were examined and the compatibility with specified values of JIS A 8603 was studied. As a result, it was found that JIS A 5308 can be applicable to high-strength and high-fluidity concretes and compatible to the specified values of JIS A 8603.

When a set-retarding agent and a superplasticizer are added, the returned concrete can be reused as a preceding mortar for concrete pumping constructions. The experimental study was performed aiming at the practical application of the recycled mortar. Laboratory tests to determine the dosage of the set-retarding agent and the superplasticizer as well as the quality of the recycled mortar were executed. Full-scale tests for the applicability of a wet-screening equipment at a ready-mixed concrete plant, and the quality and productivity of the recycled mortar manufactured with the full-scale equipment were studied.

Applicability of molten slag originated from domestic wastes to fine aggregate for concrete was studied. Monthly changes in quality of the molten slag were taken into account and the quality of the resulting concrete, when applied to a full-scale structure, was examined in terms of fresh and hardened properties. It was found that the quality variation of the molten slag, as a fine aggregate, was sufficiently small during 8-month inspection and was within the range of TR A 0016: 2002. A molten slag fine aggregate concrete, with a water-cement ratio of 0.45 and Air Entraining and high-range water reducing agents, showed nearly the same performances, Including pumpability, compressive strength and concrete quality in structure, as those of the normal concrete.

Moderate-heat portland cement has likely been applied to mass concrete where as in this study it is applied to high-strength concrete with a designed strength ranging from 36 to 70 N/mm2. Fresh properties, strength development and temperature histories of full-scale model specimens of the high-strength concrete have been investigated. It was found that high-strength concrete with moderate-heat cement can be fully applicable to real construction practice on site. Moreover, some important prediction formulas and parameter value were derived : the maximum temperature of the model specimen with parameters of unit cement content and concrete temperatures, relationship between core strength and simplified adiabatic temperatures and a water-cement ratio by which column strengths in structure can satisfy the designed strength.

Molten slag recycled from domestic wastes can be used as a fine aggregate in concrete but not currently applied in practice. This may be attributed to the lack of example concrete structures built using the waste slag fine aggregate. In this report, a construction experiment of full-scale concrete structure built with the recycled aggregate concrete is studied. It was shown that the recycled aggregate concrete can be applied to the concrete pumping construction under the same condition as that of the normal concrete and the resulting concrete quality in the structure was satisfactory. Practical application of the waste slag fine aggregate was proven to be promising.

Ultra high strength concrete with silica fume was manufactured in a normal ready-mixed concrete plant. Properties of fresh ultra high strength concrete including minimum power load of mixer at discharge, slump flow and 50-cm flowing time were measured and discussed in terms of water-cement ratio, dosage of superplasticizer and mixed-up temperatures. It was proven to be possible for conventional ready-mixed plants to manufacture an ultra high strength concrete with favorable early-age properties up to 120 minutes after mixing.

The Broken-Off Specimens by Splitting - BOSS method was first formulated in 1985 by professor Shirayama of the University of Tsukuba. This new estimation method for concrete strength in structures has been studied subsequently by the authors in terms of practical applications. These included a simplified method and experiments under various conditions to ensure the accuracy of the test method. As a result, a standard test method with a regression equation for estimating the concrete strength in structures was proposed. Compiling these results, this paper deals with a comparative study of BOSS strength and core strength in a full-scale model structure, variance analysis of influences of sampling height and water- cement ratio of concrete on these compressive strength, and applicability of the BOSS method on the basis of these studies. High correlation was found between BOSS and core strength both in normal and high-strength concrete, and the proposed estimation equation was found to be applicable to the reliable evaluation of concrete strength in structures.

A high-strength concrete with silica fume was placed in the full-scale model column specimens and temperature histories and core compressive strengths were determined. Laboratory-scale specimens were prepared with the same concrete and their temperature histories and compressive strengths were compared with those of model columns. Effects of testing parameters, such as the number of specimen in an adiabatic curing chamber, thickness of thermal insulation of specimen jacket and the duration of curing, on the temperature history and compressive strength were discussed. The effects of the number of specimen in a chamber and the thickness of insulation on the maximum temperature and temperature increasing rate were found to be significant but insensitive to 28 and 91-day compressive strengths.

Compressive strength of cores sampled from a full-scale model specimen of high-strength concrete, placed under normal temperature conditions, were compared with those obtained from the estimated temperature curing. A temperature history under low temperature conditions was estimated from the measured data, which was then applied to specimens subjected to the estimated temperature history in a thermostatic chamber. Compressive strength of the specimens were then compared with those of cores sampled from a structure built in the winter. Reproducibility and effectiveness of the estimated temperature history curing method was thus confirmed in experiments.