EFFECT OF GROUND GRANULATED BLAST-FURNACE SLAG PROPORTION ON CREEP CHARACTERISTICS OF CONCRETE

This paper presents the experimental results on the effect of ground granulated blast-furnace slag(GGBS) on the creep characteristics of concrete.The specific creep of concrete without and with the GGBS of 30%,50% and 80% was examined in a stress strength ratio of 33% at(20±1) ℃ and humidity of 60%±5%.The results show that the GGBS has a slight effect on the creep char-acteristics of concrete with the GGBS of 30 % or 50%.The GGBS proportion of 80% gives a negative effect on the creep characteristics of concrete.The specific creep after one year was 1.74 times as much as that of concrete without any GGBS.Scanning electron microscope was used to observe the interface bonding among the GGBS,cement particles and matrix.The porosities and pore size distributions were determined by mercury intrusion porosimetry(MIP).The amount of hydration was determined by the unevaporated water.The elastic modulus of GGBS and cement were measured by nano-indentation.The creep mechanism of concrete with different GGBS proportions was analyzed.It is indicated that the GGBS particles can not reduce the creep of concrete through the micro-aggregate effect due to the lower elastic modulus.The specific creep of concrete has a positive relation with the amount of hydration products.The combined interface among cement,GGBS particles and matrix become worse,offering a negative effect on the specific creep of concrete at the GGBS of 80 %.The combined interface plays a role in the creep behavior of concrete and the amount of hydration products.