scholarly journals Influence of mineral additions on the microstructure of concrete in chloride environment

2018 ◽  
Vol 1 (1) ◽  
pp. 283-292
Author(s):  
Walid Fouad Edris ◽  
Safwat Abdelkader ◽  
Encarnacion Reyes Pozo ◽  
Amparo Moragues Terrades

In this work we have designed an experimental campaign with four different dosages of concrete to study the influence of the principal additions used in marine environments. The effect of material composition [Sulfate Resistant Portland Cement (SRPC), Blast Furnace Slag Portland Cement (BFSPC), Silica Fume (SF) and Fly Ash (FA) with four different mix designs] was performed by means of differential thermal analysis (DTA), mercury intrusion porosimetry (MIP), gas permeability, chloride diffusion and mechanical properties of concrete. In order to simulate the aggressiveness of the marine environment the concretes were immersed in a sodium chloride solution with a concentration of 1 molar during different times of 182, 365 and 546 days. According to the results obtained, the SRPC and SRPC+FA samples suffered the highest rise in permeability, porosity and chloride diffusion, and the greatest loss in compressive strength

2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Yubo Li ◽  
Shaobin Dai ◽  
Xingyang He ◽  
Ying Su

The application of ultrafine ground-granulated blast-furnace slag (GGBFS) in concrete becomes widely used for high performance and environmental sustainability. The form of ultrafine slag (UFS) used in concrete is powder for convenience of transport and store. Drying-grinding-drying processes are needed before the application for wet emission. This paper aims at exploring the performances of concrete blended with GGBFS in form of slurry. The ultrafine slag slurry (UFSS) was obtained by the process of grinding the original slag in a wet ball mill, which was mixed in concrete directly. The durations of grinding were 20 min, 40 min, and 60 min which were used to replace Portland cement with different percentages, namely, 20, 35, and 50, and were designed to compare cement with original slag concrete. The workability was investigated in terms of fluidity. Microstructure and pore structure were evaluated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and mercury intrusion porosimetry (MIP). The fluidity of concrete mixed with UFSS is deteriorated slightly. The microstructure and early strength were obviously improved with the grind duration extended.


1995 ◽  
Vol 12 (1) ◽  
pp. 83-95 ◽  
Author(s):  
JEFFREY H. BOY ◽  
TIMOTHY D. RACE ◽  
KETURAH A. REINBOLD ◽  
JOHN BUKOWSKI ◽  
XIAOFENG ZHU

2017 ◽  
Vol 71 (1) ◽  
pp. 308-314
Author(s):  
Shingo YOSHIMOTO ◽  
Tatsuo SHINMI ◽  
Hiroyoshi KATO ◽  
Takatoshi MOTOORI

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3448
Author(s):  
Chenhui Jiang ◽  
Aiying Wang ◽  
Xufan Bao ◽  
Zefeng Chen ◽  
Tongyuan Ni ◽  
...  

This paper presents an experimental investigation on geopolymer coatings (GPC) in terms of surface protection of civil structures. The GPC mixtures were prepared with a quadruple precursor simultaneously containing fly ash (FA), ground granulated blast-furnace slag (GBFS), metakaolin (MK), and Portland cement (OPC). Setting time, compressive along with adhesive strength and permeability, were tested and interpreted from a perspective of potential applications. The preferred GPC with favorable setting time (not shorter than 120 min) and desirable compressive strength (not lower than 35 MPa) was selected from 85 mixture formulations. The results indicate that balancing strength and setting behavior is viable with the aid of the multi-componential precursor and the mixture design based on total molar ratios of key oxides or chemical elements. Adhesive strength of the optimized GPC mixtures was ranged from 1.5 to 3.4 MPa. The induced charge passed based on a rapid test of coated concrete specimens with the preferred GPC was 30% lower than that of the uncoated ones. Setting time of GPC was positively correlated with η[Si/(Na+Al)]. An abrupt increase of setting time occurred when the molar ratio was greater than 1.1. Compressive strength of GPC was positively affected by mass contents of ground granulated blast furnace slag, metakaolin and ordinary Portland cement, and was negatively affected by mass content of fly ash, respectively. Sustained seawater immersion impaired the strength of GPC to a negligible extent. Overall, GPC potentially serves a double purpose of satisfying the usage requirements and achieving a cleaner future.


2019 ◽  
Vol 110 ◽  
pp. 01055
Author(s):  
Liliya Kazanskaya ◽  
Nicolay Privalov ◽  
Svetlana Privalova

Nowadays, it is acknowledged that the use of mineral additives based on ground slag is one of ways of resource saving and improvement of technical properties of cement composites. Mineral additives with fineness similar to the Portland cement fineness are often used to replace part of Portland cement. Two kinds of ultra-fine ground granulated blast furnace slag that differ in composition and fineness were studied in the paper. Water-reduction due to effect of super plasticizer in slag-Portland cement compositions with amount of slag up to 70% was studied. The results of reduction of binder quantity per 1 kg of chemical admixture due to significant water-reduction are obtained and analysed. Correlations depending on kind, amount and fineness of slags, as well as depending on mineralogical composition of Portland cement were stated. The ultra-fine mineral additives based on ground slag with high specific surface area can be used for significant reduction of compositional binder.


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