The EFFECT Of Curing Conditions on the Hydration and Strength Development in Fondu: Slag

1990 ◽  
pp. 288-297
2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Mengyuan Li ◽  
Qiang Wang ◽  
Jun Yang

A comparison was made between the impact of raising the thermostatic temperature and the impact of prolonging the thermostatic time on the performance of steam-cured concrete containing a large portion of fly ash (FA) or ground granulated blast furnace slag (GGBS) by analysing the form removal strength, chemically combined water content, reaction degree, strength development, chloride permeability, and volume stability. For the materials and test conditions reported in this study, raising the thermostatic temperature is more favourable for concrete containing FA, as indicated by the significantly higher form removal strength and the higher growth of reaction degree of FA compared with prolonging the thermostatic time. With an increase in the thermostatic temperature, the hydration degree of a binder containing FA or GGBS initially increases and subsequently decreases. Although concrete containing FA can obtain satisfactory form removal strength with steam curing at 80°C, the late strength development of concrete containing FA is slow for the same curing conditions. The effect of the late performance of resistance to chloride ion permeability improved by FA is better than the effect improved by GGBS. The risk of destroying the structure of concrete containing a large portion of FA or GGBS due to delayed ettringite formation (DEF) is minimal when specimens were steam-cured at 80°C.


2012 ◽  
Vol 626 ◽  
pp. 931-936 ◽  
Author(s):  
Liew Yun Ming ◽  
Kamarudin Hussin ◽  
Mohd Mustafa Al Bakri Abdullah ◽  
Mohammed Binhussain ◽  
Luqman Musa ◽  
...  

The properties of metakaolin geopolymer paste are affected by the alkali concentration, the initial raw materials, solidification process, and amount of mixing water as well as the curing conditions. This study aimed to investigate the effect of curing temperature (room temperature, 40°C, 60°C, 80°C and 100°C) and curing time (6h, 12h, 24h, 48h and 72h) on the geopolymer pastes produced from geopolymer powder. The results showed that curing at room temperature was unfeasible. Heat was required for the geopolymerization process, where strength increased as the curing temperature was increased. Moderate elevated curing temperature favored the strength development of geopolymer pastes in comparison with those treated with extreme elevated curing temperature. When geopolymer paste was subjected to extreme elevated curing temperature, shorter curing time should be used to avoid deterioration in strength gain. Similarly, longer curing time was recommended for moderate elevated curing temperature. The microstructure of geopolymer paste cured at moderate curing temperature showed obvious densification of structure. In contrast, the structure formed was weak and less compact at very high elevated curing temperature.


2020 ◽  
Vol 9 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Parameshwar N Hiremath ◽  
H P Thanu ◽  
S N Basavana Gowda ◽  
Sharan Kumar Goudar

2018 ◽  
Vol 774 ◽  
pp. 277-282
Author(s):  
Gum Sung Ryu ◽  
Kyung Taek Koh ◽  
Gi Hong An ◽  
Hyeong Yeol Kim ◽  
Sung Choi

Repair materials for concrete structures are often required to exhibit high bond strength at a concrete substrate, and it typically consists of ordinary Portland cement (OPC) incorporating expensive admixtures at a low water-to-binder ratio. Meanwhile, cementless mortar employs alkali-activation of cementless and pozzolanic precursors such as ground granulated blast-furnace slag (GGBFS) and fly ash (FA). The final product develops strength relatively faster than OPC, and its strength can be flexibly talyored by controlling the type and dosage of the activator. The present study investigates the strength development characteristic of cementles mortar for use in repair of concrete structures. Independent variables include mix proportions and curing conditions, which were chosen to optimize the performance of the cementless mortar.


2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Keun-Hyeok Yang ◽  
Jae-Sung Mun ◽  
Myung-Sug Cho

This study examined the relative strength-maturity relationship of high-strength concrete (HSC) specifically developed for nuclear facility structures while considering the economic efficiency and durability of the concrete. Two types of mixture proportions with water-to-binder ratios of 0.4 and 0.28 were tested under different temperature histories including (1) isothermal curing conditions of 5°C, 20°C, and 40°C and (2) terraced temperature histories of 20°C for an initial age of individual 1, 3, or 7 days and a constant temperature of 5°C for the subsequent ages. On the basis of the test results, the traditional maturity function of an equivalent age was modified to consider the offset maturity and the insignificance of subsequent curing temperature after an age of 3 days on later strength of concrete. To determine the key parameters in the maturity function, the setting behavior, apparent activation energy, and rate constant of the prepared mixtures were also measured. This study reveals that the compressive strength development of HSC cured at the reference temperature for an early age of 3 days is insignificantly affected by the subsequent curing temperature histories. The proposed maturity approach with the modified equivalent age accurately predicts the strength development of HSC.


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