Early-age cracking resistance of ground granulated blast furnace slag concrete

2019 ◽  
Vol 222 ◽  
pp. 278-287 ◽  
Author(s):  
Dejian Shen ◽  
Kaiqi Liu ◽  
Chuyuan Wen ◽  
Yongqiang Shen ◽  
Guoqing Jiang
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Early Age ◽  
Cracking Resistance ◽  
Granulated Blast Furnace Slag ◽  
Furnace Slag

Alkali Activation of Granulated Blast Furnace Slag

2010 ◽  
Vol 158 ◽  
pp. 1-11 ◽  
Author(s):  
Zi Qiao Jin ◽  
Xian Jun Lu ◽  
Shu Gang Hu
Keyword(s):  
Compressive Strength ◽  
Blast Furnace ◽  
Portland Cement ◽  
Blast Furnace Slag ◽  
Ordinary Portland Cement ◽  
Hydration Product ◽  
Early Age ◽  
Hydration Products ◽  
Granulated Blast Furnace Slag ◽  
Furnace Slag

In order to stimulate the potential cementitious property of granulated blast furnace slag (GBFS), the ground GBFS sample (Wei Fang Iron and Steel Corporation, China) was activated by lime and gypsum under different dosages. The results showed that lime is an effective activator for the slag, and the optimum dosage of lime is about 10% (w/w) of the slag. At the optimum dosage of lime, the 28 days compressive strength of the lime-slag paste is higher than that of 32.5 ordinary Portland cement (OPC). But, the early age strength (3 and 7 days compressive strength) of the lime-slag paste is lower than that of the OPC. Addition of gypsum can effectively improve the early age strength of the lime-slag paste. At the ratio of gypsum:lime:slag of 8.2:9.2:82.6 (w/w), both the early and long-term compressive strengths of the gypsum-lime-slag paste are higher than that of the OPC. According to XRD, TG-DTA and SEM detections of the hydration products of the lime-slag paste, the gypsum-lime-slag paste and the OPC paste, it reveals that the hydration process of the GBFS-based cementitious material is different from the ordinary Portland cement and the presence of ettringite (AFt) contributes to the early age strength of the pastes. The major hydration product of the OPC paste (<7 days) were measured as ettringite (AFt), but the AFt phase was not detected in the hydration product of the lime-slag paste and the major hydration product of the lime-slag paste was determined as amorphous CSH gel. However, AFt was detected in the hydration products of the gypsum-lime-slag paste in the early stages of hydration, and the formation of AFt is favorable for the early strength improvement of the material.

Effect of Slag Content and Hardening Accelerator Dosage on the Physico-Mechanical Properties of Cement and Concrete

2011 ◽  
Vol 324 ◽  
pp. 392-395
Author(s):  
Riad Derabla ◽  
Imen Mokrani ◽  
Mohamed Larbi Benmalek
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Mechanical Characteristics ◽  
Setting Time ◽  
Absorption Capacity ◽  
Early Age ◽  
Granulated Blast Furnace Slag ◽  
Furnace Slag ◽  
Physical And Mechanical Characteristics

Our contribution consists at the study of the effect of (0 %, 0.2 % and 0.34 %) dosage of an hardening accelerating plasticizer (Plastocrete 160, produced by Sika Aldjazair) on the properties of normal mortar and concretes prepared with portland cement artificial of Hadjar Soud cement factory (Skikda – Algeria) with addition of (10 % and 20 %) of granulated blast furnace slag finely crushed of the El Hadjar blast furnace (Annaba - Algeria). The tests are focused to the physical and mechanical characteristics of elaborated materials to knowing: setting time, porosity, water absorption capacity and the test of compressive strength at 2, 7 and 28 days. The results obtained show clearly the reliability of the additive used to accelerate the hardening and to obtain high strengths at early age, which increase by increasing of the additive dosage. For the slag, its low hydraulic capacity does not make it profitable than at the long term (beyond 28 days).

Models for Predicting Free Water and Specific Heat of Pastes Containing Ground Granulated Blast Furnace Slag

2016 ◽  
Vol 860 ◽  
pp. 135-139 ◽  
Author(s):  
Arosha Dabarera ◽  
Warangkana Saengsoy ◽  
Kanako Mori ◽  
Somnuk Tangtermsirikul
Keyword(s):  
Blast Furnace ◽  
Specific Heat ◽  
Blast Furnace Slag ◽  
Free Water ◽  
Early Age ◽  
Cement Pastes ◽  
Granulated Blast Furnace Slag ◽  
Free Water Content ◽  
High Specific Heat ◽  
Furnace Slag

This paper aims to investigate early age behavior in terms of free water content and specific heat for hardening cement paste incorporating Ground Granulated Blast Furnace Slag. Experiments were conducted to obtain free water and specific heat of slag-cement pastes by varying water to binder ratios and slag replacement levels. Free water to total binder ratios for pastes with w/b of 0.40 and slag replacements of 45% and 75% are 0.23 and 0.25 at 3 days and 0.17 and 0.19 at 28 days, respectively. Specific heat values for similar mixtures are 0.26 and 0.30 at 3 days and 0.23 and 0.25 at 28 days. Results showed that specific heat decreases as the amount of free water decreases. The slag substitution resulted in high specific heat and free water at early age but tends to decrease in long term due to enhanced reaction kinetics. Models were proposed to compute free water and specific heat by modifying existing models. The model simulations can be used to predict the measured values accurately.

scholarly journals Estimation of Ground Granulated Blast Furnace Slag and Rice Husk Ash Cementing Efficiency in Low and Medium Grade Self-Compacting Concretes

2019 ◽  
Vol 9 (1) ◽  
pp. 5044-5048
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Rice Husk Ash ◽  
Early Age ◽  
Strength Gain ◽  
Strength Enhancement ◽  
Granulated Blast Furnace Slag ◽  
Furnace Slag

Ternary blended Self Compacting Concrete (SCC) made with rice husk ash (RHA) and GGBFS (ground granulated blast furnace slag) has developed as a substitute to normal concrete. It has advantages such as less cement usage, energy usage, cost and for other ecological and socio-economic benefits. The current work quantifies the 3, 7 and 28-days cementitious efficiency for various percentages of RHA and GGBFS combination in SCC. The usage of GGBFS in M20 and M40 SCC reduces workability but increases compressive and tensile strength when compared with OPC based SCC. The optimum GGBFS is found to be 30% for low and medium strength levels of SCC. For M20 and M40, 30% GGBFS reduces workability slightly but still within desired limits. So after various trial mixes it was found that 27% GGBFS by weight of OPC and 3% RHA by weight of GGBFS quantity can be admixed to OPC SCC to achieve similar strength and workability and also better rate of strength regain in early days of hardening. In M20 and M40 grades of SCC, 3% RHA by weight of GGBFS quantity is replaced. Due to addition of GGBFS to SCC will enhance the later age compressive strength but early age compressive strength decreases while the desired workability is controlled using SP appropriately. This is true for all grades of GGBFS based SCC. In M20 GGBFS based SCC, the strength gain at 3 days is nearly 9% but the compressive strength at 28 days increased by 31%. In M40, GGBFS based SCC, the strength gain at 3 days is nearly 14% but the compressive strength at 28 days increased by 21%. RHA is added as replacement of cement to improve the early age strength of SCC. RHA addition to concrete as cement replacement may help to improve strength marginally but impacts the workability drastically so SP should be used controllably to attain the desired workability. In M20 GGBFS+RHA based SCC, the compressive strength enhancement at 3 days is 21% and the compressive strength at 28 days increased by 46%. In M40, GGBFS+RHA based SCC, the compressive strength enhancement at 3 days is 20% and at 28 days increased by 34%. Similarly tensile strength in all grades of GGBFS and RHA admixed SCC increases by around 15 to 34% in M20 grade and 9 to 36% in M40 grade SCC mix. So it can be concluded that RHA and GGBS combination principally yields early strength which is not possible in SCC mixes primary made with fly ash.

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