Drying shrinkage and microstructure characteristics of mortar incorporating ground granulated blast furnace slag and shrinkage reducing admixture

2015 ◽  
Vol 93 ◽  
pp. 267-277 ◽  
Author(s):  
Wenyan Zhang ◽  
Yukio Hama ◽  
Seung Hyun Na
2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Jun Yang ◽  
Qiang Wang ◽  
Yuqi Zhou

Plain cement concrete, ground granulated blast furnace slag (GGBS) concrete, and fly ash concrete were designed. Three wet curing periods were employed, which were 2, 5, and 8 days. The drying shrinkage values of the concretes were measured within 1 year after wet curing. The results show that the increasing rate of the drying shrinkage of concrete containing a mineral admixture at late age is higher than that of plain cement concrete regardless of the wet curing time. With the reduction of wet curing time, the increment of total drying shrinkage of concrete decreases with the decrease of the W/B ratio. The negative effects on the drying shrinkage of fly ash concrete due to the reduction of the wet curing time are much more obvious than those of GGBS concrete and plain cement concrete. Superfine ground granulated blast furnace slag (SGGBS) can reduce the drying shrinkage of GGBS concrete and fly ash concrete when the wet curing time is insufficient.


2018 ◽  
Vol 12 (1) ◽  
pp. 430-440 ◽  
Author(s):  
Hongzhu Quan ◽  
Hideo Kasami

Introduction:Although hundreds million tons of concrete wastes have been generated annually in China, the use of recycled aggregate for concrete is limited because of low density and high absorption due to adhered cement paste and mortar.Methods:A new method to produce high quality recycled aggregate by heating and grinding concrete rubbles to separate cement portions adhering to aggregate was developed recently. In this process by-product powder with the fineness of 400m2/kg is generated. By-product recycled fine powder consists of fine particles of hydrated cement and crushed aggregate. To use the recycled fine powder as concrete additives two series of experiments were performed to make clear of the effect of recycled fine powder.Results and Conclusion:Self-compacting concrete with recycled fine powder, granulated blast furnace slag and granulated limestone were tested for slump flow, compressive strength, modulus of elasticity and drying shrinkage. Reduction in super plasticizing effect of high range water reducer was found for concrete with recycled powder. Compressive strength of concrete with recycled fine powder was the same as those with granulated limestone, and lower than those with granulated blast furnace slag. Concrete with recycled fine powder showed lower elastic modulus and higher drying shrinkage than those with granulated blast furnace slag and granulated limestone. The recycled fine powder is usable for self-compacting concrete without further processing, despite the possible increase in dosage of high range water reducer for a given slump flow and in drying shrinkage. The addition of granulated blast furnace slag together with recycled powder to self-compacting concrete improved super plasticizing effect of high range water reducer and properties of concrete.


2011 ◽  
Vol 250-253 ◽  
pp. 866-869 ◽  
Author(s):  
Hong Zhu Quan

To utilize the recycled powder as concrete additives, self-compaceing concerte with recycled powder, granulated blast-furnace slag and granulated limestone were tested for slump-flow, compressive strength, modulus of elasticity and drying shrinkage. Reduction in superplasticizing effect of high-range water reducer was found for concrete with recycled powder. Compressive strength of concrete with recycled powder were the same as those with granulated limestone, and lower than those with granulated blast-furnace slag. Concrete with recycled powder showed lower elastic modulus and higher drying shrinkage than those with granulated blast-furnace slag and granulated limestone. The addition of granulated blast-furnace slag together with recycled powder to self-compacting concrete improved superplasticizing effect of high-range water reducer and properties of concrete.


2019 ◽  
Vol 4 (4) ◽  
pp. 69 ◽  
Author(s):  
Bernard A. Zulu ◽  
Shingo Miyazawa ◽  
Nobukazu Nito

Accelerated curing is used for mass production in the precast concrete industry. Autogenous shrinkage and drying shrinkage occur in concrete, during and after accelerated curing. Thus, thermal cracks may occur in concrete due to both heating and cement hydration at early age, whereas drying shrinkage causes cracks after demolding. Ground granulated blast-furnace slag cement (GGBS), a byproduct in steel manufacture, has been used to improve concrete strength development during accelerated curing but poses a challenge of increased shrinkage. In this paper, two types of granulated blast-furnace slag cements were used to study mechanical and shrinkage properties of water cured and concrete subjected to accelerated curing. Limestone powder and gypsums, with two different types of fineness, were other additives used. An accelerated one day curing cycle was adopted that consisted of a 3 h delay period, heating to 65 °C, a peak temperature maintained for 3 h, and, finally, cooling. The results indicated that increment in gypsum fineness increased concrete expansion at one day for both sealed and accelerated cured concrete. In drying condition, similar shrinkage was observed. The addition of gypsum provided slightly lower shrinkage, and this may help to reduce cracking of concrete. Limestone powder improved concrete strength at early age. The difference in blast-furnace cement fineness did not have significant differences in compressive strengths, especially at 28 days.


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