scholarly journals Effect of Ground Granulated Blast Furnace Slag Replacement Ratio on Structural Performance of Precast Concrete Beams

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7159
Author(s):  
Yong-Jun Lee ◽  
Hyeong-Gook Kim ◽  
Kil-Hee Kim

This study was conducted to investigate the effect of ground granulated blast furnace slag on the structural performance of precast concrete beams, evaluating the flexural, shear and bonding performance by using the replacement ratio of the ground granulated blast furnace slag as a variable. The design strength of the concrete was set at 45 MPa in consideration of the characteristics of precast concrete products, and the replacement ratio of the ground granulated blast furnace slag to replace cement was 30 to 70%. The experimental results showed that all specimens had similar behavioral characteristics regardless of the replacement ratio of the ground granulated blast furnace slag. Comparison of the prediction results obtained by ACI 318-19 and EC 2 showed that the mean flexural strength and shear strength were higher than 1.19 and 1.43, respectively, and the mean bond strength was 1.57, satisfying the required performance. Therefore, the experimental results showed that in using the ground granulated blast furnace slag as an admixture for precast concrete, the cement replacement ratio may be increased up to 70% without causing any problems in securing the structural performance. Summarizing the results of the present study, a ground granulated blast furnace slag replacement ratio of 50% or lower may be reasonably applied.

2017 ◽  
Vol 12 (3) ◽  
pp. 456-469 ◽  
Author(s):  
Toshiki Ayano ◽  
◽  
Takashi Fujii ◽  
Kyoji Niitani ◽  
Katsunori Takahashi ◽  
...  

Concrete deck slabs of bridges are often deteriorated by heavy traffic and freezing and thawing actions. Spraying salt during the winter further promotes the deterioration of concrete. Some reports estimate that the length of highway roads requiring the renewal of deteriorated concrete slabs exceeds 230 km. In order to extend the lifespan of damaged bridge girders, the load for these girders must not be increased. This means that prestressed concrete (hereafter, PC) members are desirable to sustain bridge life, because they can be thinner than reinforced concrete (hereafter, RC) members. In addition, to shorten the period of traffic regulation during renewal construction, precast members should be applied. One problem in manufacturing durable precast concrete is steam curing. When the temperature, period, or both of the steam curing process are inadequate, the effect of air-entraining (hereafter, AE) agents is lost because the warmed air trapped by the AE agent expands and escapes from the concrete. Another problem is concrete fatigue. It is well known that the fatigue lives of concrete slabs in wet conditions are much shorter than those in dry conditions. Concrete slabs are waterproofed immediately after construction, but the waterproofing can be fractured soon after opening bridges, and water can reach the concrete surface. The lifespan of concrete slabs in contact with water often depends on the fatigue of the concrete. Granulated blast furnace slag sand (hereafter, BFS) can enhance the resistance to freezing and thawing actions without using AE agents. Therefore, the resistance to freezing and thawing of concrete mixed with BFS is not damaged by steam curing. The fatigue of concrete in water is also improved by the addition of BFS. Furthermore, BFS can reduce the drying shrinkage of concrete. It is advantageous to restrict the loss of prestress in PC. This study shows that precast PC members with high durability can be manufactured when granulated blast furnace slag is used as a fine aggregate in the concrete. BFS reacts with cement hydrates. It is well known that the carbonation of concrete with ground granulated blast furnace slag (hereafter, GGBF) is much greater than that with ordinary binder. However, BFS does not accelerate the carbonation of concrete. When using granulated blast furnace slag as a fine aggregate, no disadvantage in the concrete properties is detected.


Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 442 ◽  
Author(s):  
Hyun-Min Yang ◽  
Seung-Jun Kwon ◽  
Nosang Vincent Myung ◽  
Jitendra Kumar Singh ◽  
Han-Seung Lee ◽  
...  

Ground granulated blast furnace slag (GGBFS) conventionally has been incorporated with ordinary Portland cement (OPC) owing to reduce the environmental load and enhance the engineering performance. Concrete with GGBFS shows different strength development of normal concrete, but sensitive, to exterior condition. Thus, a precise strength evaluation technique based on a quantitative model like full maturity model is required. Many studies have been performed on strength development of the concrete using equivalent age which is based on the apparent activation energy. In this process, it considers the effect of time and temperature simultaneously. However, the previous models on the apparent activation energy of concrete with mineral admixtures have limitation, and they have not considered the effect of temperature on strength development. In this paper, the apparent activation energy with GGBFS replacement ratio was calculated through several experiments and used to predict the compressive strength of GGBFS concrete. Concrete and mortar specimens with 0.6 water/binder ratio, and 0 to 60% GGBFS replacement were prepared. The apparent activation energy (Ea) was experimentally derived considering three different curing temperatures. Thermodynamic reactivity of GGBFS mixed concrete at different curing temperature was applied to evaluate the compressive strength model, and the experimental results were in good agreement with the model. The results show that when GGBFS replacement ratio was increased, there was a delay in compressive strength.


2017 ◽  
Vol 2017 ◽  
pp. 1-6
Author(s):  
Wonsuk Jung ◽  
Se-Jin Choi

This paper investigates the effect of the high-temperature curing methods on the compressive strength of concrete containing high volumes of ground granulated blast-furnace slag (GGBS). GGBS was used to replace Portland cement at a replacement ratio of 60% by binder mass. The high-temperature curing parameters used in this study were the delay period, temperature rise, peak temperature (PT), peak period, and temperature down. Test results demonstrate that the compressive strength of the samples with PTs of 65°C and 75°C was about 88% higher than that of the samples with a PT of 55°C after 1 day. According to this investigation, there might be optimum high-temperature curing conditions for preparing a concrete containing high volumes of GGBS, and incorporating GGBS into precast concrete mixes can be a very effective tool in increasing the applicability of this by-product.


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