Relationship between Internal Relative Humidity and Autogenous Shrinkage of Cement Paste with Supplementary Cementitious Materials (SCM)

2013 ◽  
Vol 539 ◽  
pp. 35-39 ◽  
Author(s):  
Yue Li ◽  
Qian Qian Yan
Keyword(s):  
Fly Ash ◽  
Relative Humidity ◽  
Autogenous Shrinkage ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Cement Pastes ◽  
Different Types ◽  
Influence Of Water ◽  
Internal Relative Humidity ◽  
Main Factor

The influence of water to binder (W/B), types and dosage of supplementary cementitious materials (SCM) on the internal relative humidity (IRH) and autogenous shrinkage (AS) of cement pastes caused by self-desiccation were investigated, and their relationship was discussed. The results show that, W/B is a main factor that affects IRH change and AS of cement pastes with SCM. With the decrease of W/B, IRH of cement pastes decreases, but AS of cement pastes increases. Different types and dosages of SCM affect the IRH differently; fly ash (FA) reduces AS, silica fume (SF) increases AS, and the effect of GBFS on AS is between FA and GBFS. The linear correlation between the change of IRH and AS of cement pastes with SCM is established.

scholarly journals New Approach for the Determination of Radiological Parameters on Hardened Cement Pastes with Coal Fly Ash

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 475
Author(s):  
Ana María Moreno de los Reyes ◽  
José Antonio Suárez-Navarro ◽  
Maria del Mar Alonso ◽  
Catalina Gascó ◽  
Isabel Sobrados ◽  
...  
Keyword(s):  
Fly Ash ◽  
Activity Concentration ◽  
Gamma Ray ◽  
Coal Fly Ash ◽  
Cementitious Materials ◽  
New Method ◽  
Supplementary Cementitious Materials ◽  
Hardened Cement ◽  
Cement Pastes ◽  
Activity Concentrations

Supplementary cementitious materials (SCMs) in industrial waste and by-products are routinely used to mitigate the adverse environmental effects of, and lower the energy consumption associated with, ordinary Portland cement (OPC) manufacture. Many such SCMs, such as type F coal fly ash (FA), are naturally occurring radioactive materials (NORMs). 226Ra, 232Th and 40K radionuclide activity concentration, information needed to determine what is known as the gamma-ray activity concentration index (ACI), is normally collected from ground cement samples. The present study aims to validate a new method for calculating the ACI from measurements made on unground 5 cm cubic specimens. Mechanical, mineralogical and radiological characterisation of 28-day OPC + FA pastes (bearing up to 30 wt % FA) were characterised to determine their mechanical, mineralogical and radiological properties. The activity concentrations found for 226Ra, 212Pb, 232Th and 40K in hardened, intact 5 cm cubic specimens were also statistically equal to the theoretically calculated values and to the same materials when ground to a powder. These findings consequently validated the new method. The possibility of determining the activity concentrations needed to establish the ACI for cement-based materials on unground samples introduces a new field of radiological research on actual cement, mortar and concrete materials.

scholarly journals Synthesis of a New Polycarboxylate at Room Temperature and Its Influence on the Properties of Cement Pastes with Different Supplementary Cementitious Materials

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Shuncheng Xiang ◽  
Yingli Gao ◽  
Caijun Shi
Keyword(s):  
Room Temperature ◽  
Autogenous Shrinkage ◽  
Drying Shrinkage ◽  
Cementitious Materials ◽  
Heat Evolution ◽  
Hydration Heat ◽  
Supplementary Cementitious Materials ◽  
Cement Pastes ◽  
Binder Ratio ◽  
Water Binder Ratio

Three polycarboxylates with different comb structures (i.e., the same degree of polymerization in side chains but different main chains) were synthesized via radical polymerization reaction at room temperature. The effect of polycarboxylates on the surface tension and the flowability in cement pastes was determined. The best product was selected to study its effects on the hydration heat evolution, compressive strength, autogenous shrinkage, and drying shrinkage of cement pastes with different kinds and contents of supplementary cementitious materials. The results showed that with the increase of molar ratio between AA and TPEG to 6 : 1, we could synthesis the best product. When the water-binder ratio was 0.4, with the increase of polycarboxylates, the cement hydration heat evolution had been slowed down, and the more the dosage was, the more obvious the effect was. Adding supplementary cementitious materials to cement under the same experimental conditions also played a mitigation role in slowing down the hydration heat. When the water-binder ratio was 0.3, supplementary cementitious materials could increase the strength of cement by 24.5% in maximum; its autogenous shrinkage and drying shrinkage could be decreased, respectively, by 60.1% and 21.9% in the lowest.

scholarly journals Effect of High Calcium Fly Ash, Ladle Furnace Slag, and Limestone Filler on Packing Density, Consistency, and Strength of Cement Pastes

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 301
Author(s):  
Eleftherios K. Anastasiou
Keyword(s):  
Fly Ash ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Strength Development ◽  
Ladle Furnace ◽  
Limestone Filler ◽  
Cement Pastes ◽  
High Calcium ◽  
High Calcium Fly Ash ◽  
Furnace Slag

Environmental considerations and technical benefits have directed research towards reducing cement clinker content in concrete, and one of the best ways to do this is to replace cement with supplementary cementitious materials. High calcium fly ash, ladle furnace slag, and limestone filler were investigated as supplementary cementitious materials in cement pastes, and binary mixtures were produced at 10%, 20%, and 30% cement replacement rates for each material. The water requirement for maximum packing and for normal consistency were obtained for each paste, and strength development was determined at 3, 7, 28, and 90 days for the 20% replacement rate. Furthermore, two ternary mixtures at 30% cement replacement were also prepared for maximum packing density and tested for compressive strength development. The results showed that high calcium fly ash decreased cement paste packing and increased water demand but contributed to strength development through reactivity. Ladle furnace slag and limestone filler, on the other hand, were less reactive and seemed to contribute to strength development through the filler effect. The ternary paste with 70% cement, 20% high calcium fly ash, and 10% limestone filler showed equivalent strength development to that of the reference cement paste.

scholarly journals Effect of Supplementary Materials on the Autogenous Shrinkage of Cement Paste

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3367 ◽  
Author(s):  
Tianshi Lu ◽  
Zhenming Li ◽  
Hao Huang
Keyword(s):  
Blast Furnace ◽  
Fly Ash ◽  
Relative Humidity ◽  
Cement Paste ◽  
Blast Furnace Slag ◽  
High Performance Concrete ◽  
Autogenous Shrinkage ◽  
Chemical Shrinkage ◽  
Internal Relative Humidity ◽  
Furnace Slag

In recent years more and more attention has been given to autogenous shrinkage due to the increasing use of high-performance concrete, which always contains supplementary materials. With the addition of supplementary materials—e.g., fly ash and blast furnace slag—internal relative humidity, chemical shrinkage and mechanical properties of cement paste will be affected. These properties significantly influence the autogenous shrinkage of cement paste. In this study, three supplementary materials—i.e., silica fume, fly ash and blast furnace slag—are investigated. Measurements of final setting time, internal relative humidity, chemical shrinkage, compressive strength and autogenous deformation of the cement pastes with and without supplementary materials are presented. Two water-binder ratios, 0.3 and 0.4, are considered. The effects of different supplementary materials on autogenous shrinkage of cement paste are discussed.

Effect of ground granulated blast funrnace slag and fly ash on strength, permeability, and under-water abrasion of fine-grained concrete

2020 ◽  
Vol 71 (7) ◽  
pp. 775-788
Author(s):  
Quyet Truong Van ◽  
Sang Nguyen Thanh
Keyword(s):  
Fly Ash ◽  
Concrete Strength ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Chloride Permeability ◽  
Cement Replacement ◽  
Fine Grained ◽  
Granulated Blast Furnace Slag ◽  
Compressive Strength Test ◽  
Economic Ground

The utilisation of supplementary cementitious materials (SCMs) is widespread in the concrete industry because of the performance benefits and economic. Ground granulated blast furnace slag (GGBFS) and fly ash (FA) have been used as the SCMs in concrete for reducing the weight of cement and improving durability properties. In this study, GGBFS at different cement replacement ratios of 0%, 20%, 40% and 60% by weight were used in fine-grained concrete. The ternary binders containing GGBFS and FA at cement replacement ratio of 60% by weight have also evaluated. Flexural and compressive strength test, rapid chloride permeability test and under-water abrasion test were performed. Experimental results show that the increase in concrete strength with GGBFS contents from 20% to 40% but at a higher period of maturity (56 days and more). The chloride permeability the under-water abrasion reduced with the increasing cement replacement by GGBFS or a combination of GGBFS and FA

scholarly journals Investigation of C-S-H in ternary cement pastes containing nanosilica and highly-reactive supplementary cementitious materials (SCMs): Microstructure and strength

2019 ◽  
Vol 198 ◽  
pp. 445-455 ◽  
Author(s):  
Daniel da Silva Andrade ◽  
João Henrique da Silva Rêgo ◽  
Paulo Cesar Morais ◽  
Anne Neiry de Mendonça Lopes ◽  
Moisés Frías Rojas
Keyword(s):  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Cement Pastes
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