Effects of Carbonate Additions on Heat of Hydration and Sulfate Resistance of Portland Cements

2009 ◽  
pp. 73-73-9 ◽  
Author(s):  
RD Hooton
Keyword(s):  
Heat Of Hydration ◽  
Portland Cements ◽  
Sulfate Resistance

scholarly journals Portland Cements with High Content of Calcined Clay: Mechanical Strength Behaviour and Sulfate Durability

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4206 ◽  
Author(s):  
Carlos H. Aramburo ◽  
César Pedrajas ◽  
Rafael Talero
Keyword(s):  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Chemical Effect ◽  
Portland Cements ◽  
Calcined Clay ◽  
Blended Cements ◽  
Sulfate Resistance ◽  
Type Iv ◽  
Mechanical Strengths ◽  
Mineralogical Compositions

Calcined clay has become the supplementary cementitious materials with the greatest potential to reduce the clinker/cement. In this research, the mechanical strengths and sulphate resistance of blended cements with a high content of calcined clay as a pozzolanic addition were evaluated to demonstrate that these cements could be designed as CEM (cement) type IV/A-SR and IV/B-SR cements by the current European standard UNE-EN 197-1: 2011. The blended cements were prepared by two Portland cements (P1 and PY6) with different mineralogical compositions and a calcined clay. The level of replacement was greater than 40% by weight. The results obtained confirm the decrease in the mechanical strengths and the increase in the sulfate resistance of the two Portland cements when they are replaced by calcined clay at a level of replacement greater than 40%. These results are a consequence of the chemical effect from the pozzolanic activity of the calcined clay. Therefore, there is an important decrease in portlandite levels of paste liquid phase that causes the increase in sulfate resistance and the decrease of the mechanical strengths.

Status of ASTM and Other National Standards for the Use of Fly Ash Pozzolans in Concrete

1986 ◽  
Vol 86 ◽  
Author(s):  
Richard M. Majko
Keyword(s):  
Fly Ash ◽  
Activity Index ◽  
Hydrated Lime ◽  
Test Methods ◽  
General Purpose ◽  
Standard Test ◽  
Heat Of Hydration ◽  
Pozzolanic Activity ◽  
National Standards ◽  
Sulfate Resistance

ABSTRACTThe Subcommittee of ASTM that is responsible for pozzolan specifications, (C09.03.10) is currently revising C 618, the standard specification, and C 311, the standard test methods. It is no small task. It is generally considered that dividing fly ashes into two classifications (Class F and Class C) is no longer acceptable. The Subcommittee has reached the tentative conclusion that one class of fly ash pozzolan is more appropriate and less ambiguous, provided it is accompanied by an optional table outlining the appropriate limits for sulfate resistance, heat of hydration, hydraulic properties, etc. That is, the engineer need specify only a fly ash pozzolan. If the engineer needs more than a “general purpose” fly ash he calls for special characteristics from the optional requirement table. Any major revision in the C 618 specification challenges the Subcommittee to look for better and more useful test methods in C 311. The committee is looking at C 1012 for a sulfate resistance procedure, conduction calorimetry as a heat of hydration method, and better methods to evaluate pozzolanic activity. The committee is aware of the limited usefulness of hydrated lime or sodium hydroxide in evaluating pozzolanic activity. Perhaps a more suitable term, i.e. the activity index with cement, is more appropriate. Fly ash properties that need to be evaluated include water reduction, activation by lime and alkalies, hydraulic or self-cementing properties and pozzolanic activity. Any test that tends to compensate for a fly ash's lower reactivity (i.e., accelerated thermal curing at 35°C or 65°C) probably leads to misleading results. A critical look at the national standards of other countries might allow the committee to take a visionary yet practical approach toward a new fly ash specification.

Numerical Simulation of Autogenous Shrinkage of Eco-Friendly Blended Portland Cements Using a Multi-Component Hydration Model

2008 ◽  
Vol 569 ◽  
pp. 261-264 ◽  
Author(s):  
Xiao Yong Wang ◽  
Han Seung Lee ◽  
Seung Min Lim
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Ordinary Portland Cement ◽  
Autogenous Shrinkage ◽  
Heat Of Hydration ◽  
Curing Temperature ◽  
Portland Cements ◽  
Influence Of Water ◽  
Hydration Model ◽  
Numerical Program

Fly ash and granulated blast-furnace slag, which are used as blends of Portland cement, are waste materials produced in electric and energy industry. Due to excellent durability, low heat of hydration, energy-saving, resource-conserving, and generally less expensive than ordinary Portland cement, blends Portland cements is used increasingly in construction industry. Both ecology benefit and economic benefit can be achieved by using blended Portland cement. Addition of blended components to cement, especially such as fly ash or silica fume, will lead to a densification of the microstructure. The autogenous shrinkage deformation will increase and the following autogenous shrinkage crack will do harm to durability of concrete structure. In this paper, based on the multi-component hydration model, a numerical program is built to predict autogenous shrinkage of ordinary Portland cement and blended Portland cement. The numerical program considers the influence of water to cement ratio, curing temperature, particle size distribution, cement mineral components on hydration process and autogenous shrinkage. The prediction result agrees well with experiment result.

scholarly journals Sulfate resistance of calcined clay – Limestone – Portland cements

2019 ◽  
Vol 116 ◽  
pp. 238-251 ◽  
Author(s):  
Zhenguo Shi ◽  
Sergio Ferreiro ◽  
Barbara Lothenbach ◽  
Mette Rica Geiker ◽  
Wolfgang Kunther ◽  
...  
Keyword(s):  
Portland Cements ◽  
Calcined Clay ◽  
Sulfate Resistance
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