Time Depndence of pH in a Cementitious Repository

1988 ◽  
Vol 127 ◽  
Author(s):  
Alan Atkinson ◽  
Nicoia M. Everitt ◽  
Richard M. Guppy
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Soluble Ions ◽  
Fuel Ash ◽  
Pulverized Fuel ◽  
Waste Repository ◽  
Pulverized Fuel Ash ◽  
Furnace Slag ◽  
Cement Compounds

ABSTRACTThe pH of a cementitious radioactive waste repository is expected to decrease with time as water leaches out soluble ions or as a result of reactions between repository constituents. These processes have been simulated in the laboratory and the results compared with behaviour anticipated from the known chemistry of cement compounds.The studies indicate that the pH in Portland cements and Blast Furnace Slag cements (BFS) is likely to remain above 10.5 for very long periods of time, of the order of several hundred thousand years for a typical repository. They also show that extensive use of Pulverized Fuel Ash (PFA) leads to uncertainty in long term pH which could be as low as 9 to 10 in some cases.

Cements in radioactive waste disposal: some mineralogical considerations

1985 ◽  
Vol 49 (351) ◽  
pp. 211-221 ◽  
Author(s):  
C. E. McCulloch ◽  
M. J. Angus ◽  
R. W. Crawford ◽  
A. A. Rahman ◽  
F. P. Glasser
Keyword(s):  
Blast Furnace ◽  
Radioactive Waste ◽  
Blast Furnace Slag ◽  
Radioactive Waste Disposal ◽  
Composite Matrix ◽  
Fuel Ash ◽  
Pulverized Fuel ◽  
Pulverized Fuel Ash ◽  
Furnace Slag

AbstractCementitious matrices are being assessed for immobilization of radioactive wastes. This paper discusses some mineralogical aspects of cement chemistry and the uses of siliceous minerals as selective sorbants to enhance immobilization potential.Studies of sorption and leaching of caesium from pulverized fuel ash (PFA), blast furnace slag, tobermorite, xonotlite, and clinoptilolite are reported. The role of incorporation of these additives in cement and the effect on the nature of the composite matrix on caesium behaviour has been investigated. Specific mechanisms of the interaction of additives with highly alkaline cement environment are described. While slags, PFA, and clinoptilolite undergo reaction at different rates, tobermorite and xonotlite appear to be stable in cement.

scholarly journals Effects of ground granulated blast furnace slag and pulverized fuel ash on rheology of concrete

2020 ◽  
Vol 39 (1) ◽  
pp. 97-104
Author(s):  
A.S. Bature ◽  
M. Khorami ◽  
A. Lawan
Keyword(s):  
Blast Furnace ◽  
Portland Cement ◽  
Yield Stress ◽  
Blast Furnace Slag ◽  
Granulated Blast Furnace Slag ◽  
Fuel Ash ◽  
Pulverized Fuel ◽  
Dynamic Yield ◽  
Pulverized Fuel Ash ◽  
Furnace Slag

The rheology of concrete containing Pulverized Fuel Ash (PFA) and Ground Granulated Blast Furnace Slag (GGBS) has been scarcely studied and reported, despite their increase application as Supplementary Cementitious Materials (SCM) that drives improvement of sustainability of the construction industry. This work studied the effect of these SCMs and Superplasticizer proportions on rheological properties of concrete using rate controlled concrete rheometer. Two groups of mixes containing replacement or addition on mass basis using either PFA or GGBS or their combinations were derived from the control mix. The dynamic yield stress, plastic viscosity and 28 day compressive strength of the control mix are 1258 Pa, 6 PaS, and 40.5 MPa respectively. The results of the rheology tests of the various binary mixes (PFA and Portland cement) and ternary mixes (Portland cement, PFA and GGBS) structural concrete shows wide disparity in the measured rheological parameters. The results show that the decrease in dynamic yield stress of the ternary mix containing 20% GGBS is 4.1%, whereas the decrease in dynamic stress of the ternary mix containing 20% PFA is 35.9% compared to the control ternary mix. The high volume Portland cement replaced ternary concrete can therefore be effectively characterized as a workable and pumpable concrete. Keywords: Rheology, PFA, GGBS, superplasticizer, concrete.

scholarly journals DURABILITY PROPERTIES OF TERNARY BLENDED FLOWABLE HIGH PERFORMANCE CONCRETE CONTAINING GROUND GRANULATED BLAST FURNACE SLAG AND PULVERIZED FUEL ASH

2019 ◽  
Vol 81 (4) ◽  
Author(s):  
Cheah Chee Ban ◽  
Chow Wee Kang
Keyword(s):  
Blast Furnace Slag ◽  
High Performance ◽  
High Performance Concrete ◽  
Durability Properties ◽  
Granulated Blast Furnace Slag ◽  
Concrete Production ◽  
Fuel Ash ◽  
Pulverized Fuel ◽  
Pulverized Fuel Ash ◽  
Furnace Slag

The use of ordinary Portland cement as the primary binder in concrete production resulted in the high carbon footprint of the concrete material which cause a great deal of environmental impacts over the years. The consumption of OPC is especially significant for high strength concrete, which require a very high cement content (more than 450 kg/m3). Hence, supplementary cementitious materials such as ground granulated blast furnace slag (GGBS) and pulverized fuel ash (PFA) were chosen as partial replacement materials of OPC for concrete production in the research due to their ease of availability from the steelmaking manufacturing sectors and coal-fired electricity power stations in the country. As the sustainability of concrete is also our main concern, the durability performance of flowable high performance concrete containing high volume of GGBS and PFA (50-80% replacement of OPC) has been studied in this research. Therefore, the durability properties of flowable high performance concrete had been assessed in term of air permeability, porosity, water absorption and capillary action. From the results of assessment, all ternary blended concrete mixes exhibited better durability performances than control OPC concrete at later ages due to formation of denser microstructure by pozzolanic reaction of GGBS and PFA. It is concluded that the mix proportion of flowable high performance concrete production with 60% replacement of OPC by GGBS and PFA has the optimum durability performances than OPC concrete.

scholarly journals LONG-TERM HYDRATION REACTION OF HIGH BLAST-FURNACE SLAG CEMENT

2010 ◽  
Vol 64 (1) ◽  
pp. 48-53
Author(s):  
Takeshi ANSAI ◽  
Makoto NISHIKAWA ◽  
Yosaku IKEO ◽  
Etsuo SAKAI
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Hydration Reaction ◽  
Slag Cement ◽  
Furnace Slag

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).

Microanalytical studies (X-ray photoelectron spectrometry) of surface hydration reactions of cement compounds

1983 ◽  
Vol 310 (1511) ◽  
pp. 85-92 ◽  
Keyword(s):  
Blast Furnace ◽  
Chemical Composition ◽  
Kinetic Energy ◽  
Blast Furnace Slag ◽  
X Rays ◽  
Hydration Time ◽  
X Ray ◽  
Tentative Interpretation ◽  
Furnace Slag ◽  
Cement Compounds

X-ray photoelectron spectrometry (X.p.s.) measures the kinetic energy of electrons photoejected from a solid surface by soft X-rays. The kinetic energy of the photoelectrons can be related to the binding energy that these electrons had originally in the solid. X.p.s. is a rather new technique for studying cements. It has been used recently in the surface analysis of C 3 S, C 2 S, C 3 A and blast-furnace slag grains during their hydration. Changes in chemical composition have been found as soon as the surface comes into contact with water, shown by a change in the shape, position an intensity of characteristic peaks like Ca 2p , Si 2p , O l8 and a reduction of characteristic ratios Ca/Si or Al/Si. A tentative interpretation of X.p.s. kinetic curves as a function of hydration time is presented.

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