The early-age properties and relationships between hydration heat and autogenous shrinkage in high-strength mass concrete of different mixture proportions are investigated through analysis of the history curves of hydration heat and autogenous shrinkage. The hydration temperature and hydration heating velocity (HHV) of the concrete were found to increase with increases in specimen size and decrease when the concrete contained a retarder, fly ash (FA) and ground granulated blast-furnace slag (GGBS). Even in samples of the same mixture proportion, autogenous shrinkage was noted to become greater as the inner temperature increased. The autogenous shrinkage of highstrength mass concrete containing FA and GGBS was lower than that of ordinary Portland cement high-strength mass concrete. The autogenous shrinking velocity of concrete increased as the size of the specimen increased and decreased when the concrete contained a retarder, FA and GGBS. Finally, a close correlation was found between the hydration temperature and autogenous shrinkage at an early age: a higher HHV and a larger HHV-maturity factor led to greater autogenous shrinkage.

This study investigates the effect of desulfurization slag (DS) and gypsum (G) on the compressive strength and microstructure properties of blast furnace slag-(BFS-) based alkali-activated systems. DS is produced in a Kambara reactor process of molten iron produced in a steel production process. DS contains CaO, SiO2, Fe2O3, and SO3 and is composed of Ca(OH)2 and 2CaO·SiO2 as main compounds. In this investigation, the weight of BFS was replaced by DS at 5, 10, 15, 20, 25, and 30%. In addition, G was also applied at 9, 12, and 15% by weight of BFS to improve the compressive strength of the alkali-activated system with BFS and DS. According to this investigation, the compressive strength of the alkali-activated mixes with BFS and DS ranged from 14.9 MPa (B95D5) to 19.8 MPa (B90D10) after 91 days. However, the 28 days compressive strength of the alkali-activated mixes with BFS, DS, and G reached 39.1 MPa, 45.2 MPa, and 48.4 MPa, respectively, which were approximately 78.8 to 97.5% of that of O100 mix (49.6 MPa). The main hydrates of the BFS-DS (B80D20) binder sample were Ca(OH)2, CaCO3, and low-crystalline calcium silicate hydrates, while the main hydration product of BFS-DS-G (B75D10G15) binder was found as ettringite. The use of BFS-DS-G binders would result in the value-added utilization of steel slag and provide an environmentally friendly construction material, and contribute to a reduction of CO2 in the cement industry.

Concrete undergoes shrinkage regardless of the influence of external forces. The deformation of concrete is crucial for the structural stability of high-rise and large-scale buildings. In this study, the shrinkage and compressive creep of 70–90 MPa high-strength concrete used in high-rise buildings were evaluated based on the curing conditions (sealed/unsealed), and the existing prediction models were examined. It was observed that the curing condition does not significantly affect the mechanical properties of high-strength concrete, but the use of limestone coarse aggregate increases the elastic modulus when compared to granite coarse aggregate. The autogenous shrinkage of high-strength concrete is greater than that of normal-strength concrete owing to self-desiccation, resulting in a large variation from the value predicted by the model. The drying shrinkage was observed to be similar to that predicted by the model. Compressive creep was affected by the curing conditions, compressive strength, loading level, and loading age. The compressive creep of high-strength concrete varied significantly from the prediction results of ACI 209; ACI 209 was modified based on the measured values. The shrinkage and compressive creep characteristics of high-strength concrete must be reflected to predict the deformation of an actual structure exposed to various conditions.

In this study, to evaluate autogenous shrinkage of high-strength mass concrete with specimen size and hydration delay effects, the thermal deformation was calculated using thermal expansion coefficient (TEC) corrected by the maturity method, and was subtracted from measured total deformation. And the properties and relations of hydration heat and autogenous shrinkage at early ages were numerically analyzed. In test and analysis results, hydration temperature is affected by specimen conditions such as size and admixture, and change of hydration temperature could affect autogenous shrinkage; the higher hydration temperature and the greater autogenous shrinkage. There is a close relationship between hydration temperature and autogenous shrinkage at early ages, especially between HHV (hydration heating velocity) and ASV (autogenous shrinking velocity); the higher HHV, the higher ASV and the greater ultimate autogenous shrinkage. The points where hydration temperature and autogenous shrinkage start to increase rapidly are due to the consumption of gypsum in the cement hydration process, and are strongly related to the setting time.

Recently, many efforts related to the utilization of industrial by-products have been made to reduce carbon dioxide emissions in the construction industry. Of these various efforts, concrete incorporating ground granulated blast furnace slag (BFS) provides many advantages compared to conventional concrete, such as high long-term compressive strength, improved durability and economic benefits because of its latent hydraulic property, and low compressive strength at early curing age. This paper investigates the compressive strength of high-activated ground granulated blast furnace slag blended mortar with slag by-product S type(SBP-S). The results of the experiment revealed that incorporating high-activated ground granulated blast furnace slag would affect the compressive strength of mortar. It was found that increasing the Blaine fineness and replacement ratio of slag by-product S type shows high compressive strength of mortar at early curing age because of its high SiO2 and CaO contents in the slag. It is confirmed that an increase of curing age does not affect the compressive strength of mortar made with slag by-product S type at a high curing temperature. Moreover, it is possible to develop and design concrete manufactured with high-activated ground granulated blast furnace slag as binder considering the acceleration curing conditions and mix proportions.