Properties of concrete using high C3S cement with ground granulated blast-furnace slag

Hama

2020

Materials

The frost damage resistance of blast-furnace slag (BFS) cement is affected by carbonation. Hence, this study investigates the carbonation properties of pastes incorporating BFS with different replacement ratios, such as 15%, 45%, and 65% by weight, and different curing conditions, including air and carbonation. The BFS replacement ratio properties, determined by the Ca/Si ratio of calcium silicate hydrate in the cement paste sample, were experimentally investigated using mercury intrusion porosimetry, X-ray diffraction, and thermal analysis. The experimental investigation of the pore structure revealed that total porosity decreased after carbonation. In addition, the porosity decreased at a higher rate as the BFS replacement rate increased. Results obtained from this study show that the chemical change led to the higher replacement rate of BFS, which produced a higher amount of vaterite. In addition, the lower the Ca/Si ratio, the higher the amount of calcium carbonate originating from calcium silicate hydrate rather than from calcium hydroxide. As a result of the pore structure change, the number of ink-bottle pores was remarkably reduced by carbonation. Comparing the pore structure change in air-cured and carbonation test specimens, it was found that as the replacement rate of BFS increased, the number of pores with a diameter of 100 nm or more also increased. The higher the replacement rate of BFS, the higher the amount of calcium carbonate produced compared with the amount of calcium hydroxide produced during water curing. Due to the generation of calcium carbonate and the change in pores, the overall number of pores decreased as the amount of calcium carbonate increased.

Section: Pore Volume Of Log Differential Resultsmentioning

confidence: 68%

Effect of Blast-Furnace Slag Replacement Ratio and Curing Method on Pore Structure Change after Carbonation on Cement Paste

Hama

2020

Materials

“…It can be seen that the compressive strength of the mortar samples tends to decrease with increasing BFS replacement ratio at 1, 3, and 7 days, owing to the fact that the proportion of cement content decreases and the reaction rate of BFS is slow (Çetin et al 2016;Barnett et al 2006;Boukendakdji et al 2012;Miyazawa et al 2014;Özbay et al 2016;Jaya Prithika and Sekar 2016). In fact, it may cause a decrease in the compressive strength at an early curing age.…”

Section: Resultsmentioning

confidence: 98%

Effect of Limestone Powder and Gypsum on the Compressive Strength Mixture Design of Blast Furnace Slag Blended Cement Mortar

Zhang

et al. 2017

ACT

Journal of Advanced AbstractThis paper investigates the compressive strength development of blast furnace slag (BFS) blended mortar mixtures incorporating various mineral admixtures, namely BFS, limestone powder (LSP), and gypsum (CS). BFS replacement ratios of 15, 20, and 25 wt.%; LSP replacement ratios of 2, 3, 4, and 5 wt.%; and a CS replacement ratio of 2 wt.% are employed to improve the strength of BFS blended mortar mixtures. The hydration reaction and products resulting from the use of cement, BFS, and mineral admixtures are quantitatively examined with respect to the XRD/Rietveld method in order to investigate the relationship between the produced hydrates and the strength. Experimental investigation reveals that the mortar mixture with BFS 15 wt.%, LSP 4 wt.%, and CS 2 wt.% exhibits similar compressive strength to an ordinary Portland cement mortar mixture. In addition, the strength is found to be decreased as the BFS replacement ratio increases. At a BFS replacement ratio above 20 wt.%, LSP affects the strength improvement of BFS cement and CS affects the initial strength improvement of BFS cement.

“…Therefore, it is very important to use it more actively as an admixture for concrete. In view of the above, the use of GBFS is expected to expand more widely worldwide [ 8 , 9 , 10 , 11 , 12 , 13 ].…”

Section: Introductionmentioning

confidence: 99%

“…However, GBFS-mixed concrete also has certain disadvantages such as a delayed setting and substantial decrease in the compressive strength in the early aging stage in comparison with 100% OPC. That is why the range over which GBFS-mixed concrete can be used is limited despite its several advantages [ 10 , 11 , 12 , 13 , 14 ]. In the construction field, securing concrete with an early strength (on the first and third day of aging) is a particularly crucial factor that determines the time of removal of the forms (or the shortening of the construction time period).…”

Section: Introductionmentioning

confidence: 99%

Improvement of Early Strength of Cement Mortar Containing Granulated Blast Furnace Slag Using Industrial Byproducts

Lee

2017

Materials

Abstract:In the field of construction, securing the early strength of concrete (on the first and third days of aging) has been an important problem in deciding the mold release time (i.e., shortening the construction time period). Therefore, the problem of reduced compressive strength in the early aging stage caused by mixing granulated blast furnace slag (GBFS) with concrete must certainly be resolved. In this study, we conduct experiments to explore methods for generating a concrete that develops an early strength equivalent to that of 100% OPC. The objective of this study is the development of an early-strength accelerator (ESA) made from an industrial by-product, for a GBFS-mixed cement mortar. This study also analyzes the mechanism of the early-strength generation in the concrete to evaluate the influence of the burning temperature of ESA on the optimal compressive strength of the concrete. According to the results of the experiment, GBFS, whose ESA is burnt at 800 • C, shows an activation factor of 102.6-104.7% in comparison with 100% OPC on the first and third days during early aging, thereby meeting the target compressive strength. The results of the micro-analytic experiment are as follows: ESA showed a pH of strongly alkaline. In addition, it was found that the content of SO 3 was high in the chemical components, thus activating the hydration reaction of GBFS in the early age. This initial hydration reaction was thought to be due to the increase in the filling effect of the hydrate and the generation of C-S-H of the early age by the mass production of Ettringite.