The nanogranular behavior of C-S-H at elevated temperatures (up to 700 °C)

DeJong, Matthew J.; Ulm, Franz‐Josef

doi:10.1016/j.cemconres.2006.09.006

Cited by 240 publications

(70 citation statements)

References 27 publications

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“…The modulus and hardness of C-S-H gel were found to be between 20-40 GPa and 1-2 GPa, respectively, depending on the density of C-S-H. This is consistent with previous studies (Acker, 2001;Velez et al, 2001;Constantinides and Ulm, 2004;DeJong and Ulm, 2007;Mondal et al, 2007;Sorelli et al, 2008). Modulus and hardness varied in the cement grain, which could be pure clinker phase or the particle edge and void regions in the boundary of pure phases within the cement grain.…”

Section: Nanoindentationsupporting

confidence: 80%

“…However, to the best of our knowledge, there is no report that investigates the microscopic mechanical properties across the interface between cement grains and C-S-H gel in level III. Previous studies are mainly restricted to C-S-H phase or cement clinker (Acker, 2001;Constantinides et al, 2003;2006;Constantinides and Ulm, 2007;DeJong and Ulm, 2007;Jennings et al, 2007;Mondal et al, 2007;Vandamme et al, 2010;Davydov et al, 2011;Jones et al, 2012). This interfacial phase may play important roles across the boundary for joining mechanically dissimilar materials, i.e., cement grains and C-S-H gel, and thus an in-depth investigation is needed.…”

Section: Introductionmentioning

confidence: 99%

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Nanomechanical properties of C-S-H gel/cement grain interface by using nanoindentation and modulus mapping

Corr

Shah

2015

J. Zhejiang Univ. Sci. A

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Investigation on the mechanical properties of cement-based materials at micron and sub-micron scales is important for understanding its overall performance. Recent progress in experimental nanomechanics opens new access to nanoengineering of cement-based composites. In this study, nanoindentation and viscoelastic modulus mapping were employed to study the interfacial properties. The interface width measured by modulus mapping was around 250 nm as compared to a rough estimation of less than 5 μm by nanoindentation, due to the fact that 2 orders of magnitude increase in spatial resolution could be achieved by modulus mapping. Both the nanoindetation and modulus mapping results indicated that the modulus of the interface falls between 60-70 GPa. The packing density in the interface was non-uniform as two peaks of value were observed for the storage modulus distribution. This interface could be regarded as a dense hydration coating around cement grains, which was less permeable and hindered the further hydration of cement.

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Section: Nanoindentationsupporting

confidence: 80%

Section: Introductionmentioning

confidence: 99%

Nanomechanical properties of C-S-H gel/cement grain interface by using nanoindentation and modulus mapping

Corr

Shah

2015

J. Zhejiang Univ. Sci. A

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“…This figure shows Journal of Sustainable Cement-Based Materials 5 that calcareous sand and mortar decarbonize over 600°C whereas most of the pure cement paste is dehydrated below 600°C. Indeed, several authors [28][29][30] have shown that the dehydration of C-S-H is about 180-300°C and the dehydration of CH (Portlandite) is about 450-550°C. Therefore, a heating at 600°C has been chosen for the measurement of bound water content as it allows avoiding the decarbonation of aggregates.…”

Section: Bound Water Contentmentioning

confidence: 99%

Influence of hardened cement paste content on the water absorption of fine recycled concrete aggregates

Zhao

Rémond

Damidot

et al. 2013

Journal of Sustainable Cement-Based Materials

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A linear relationship was found between the mean size of four granular classes (0/0.63, 0.63/1.25, 1.25/2.5, 2.5/5 mm) of different laboratory-made fine recycled concrete aggregates (FRCA) and their hardened cement paste content (CPC). A method based on salicylic acid dissolution was specifically developed for the measurement of CPC. Results showed that bound water and density of FRCA were strongly correlated with their CPC. Identically, the water absorption coefficient also followed a linear trend as a function of the CPC but only for the three coarser granular classes. Indeed, the water absorption coefficient of the finer fraction of FRCA (0/0.63 mm) cannot be correctly measured using European standard method EN 1097-6 or method no. 78 of IFSTTAR; but it can be obtained by extrapolation from the previous linear trend. As a consequence, the accurate total water absorption of FRCA (fraction 0/5 mm) can be estimated.

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“…The dehydration/vaporization mechanism proposed by DeJong and Ulm [8] was shown as a possible deterioration mechanism resulting in decreased C-S-H packing factors and in turn reduced elastic modulus and hardness as measured by nanoindentation. However, unless additional secondary chemical bonding was to occur between C-S layers (similar to irreversible creep mechanisms [16] during the vaporization event, it is likely that rehydration of the C-S-H would occur slowly.…”

Section: Resultsmentioning

confidence: 99%

Nanomechanical structure-property relations of dynamically loaded reactive powder concrete

Allison¹,

Moser²,

Chandler³

et al. 2011

Materials Characterisation V

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Low water-to-cement ratio ( w / c ) reactive powder concretes (RPCs) exhibit much higher compressive strengths compared to conventional concrete through optimized particle packing and specialized curing regimes. The high strain-rate impact behavior of RPCs was investigated at the macroscale. However, little work has been done to study the fundamental material behaviors and failure mechanisms of RPC under high strain impact and penetration loads at lower length scales. These high strain-rate loadings have many possible effects on RPCs at the microscale and nanoscale, including alterations in the composition and bonding present in hydrated phases such as calcium silicate hydrate (C-S-H), in addition to fracture and debonding. In this work, the possible chemical and physical changes of RPCs under high strain-rate impact and penetration loads were investigated using a novel technique wherein nanoindentation measurements were spatially correlated with chemical composition using electron microscopy. Results indicate that high strain-rate impacts degrade both the elastic modulus and indentation hardness of RPCs and, in particular C-S-H, with damage likely occurring due to microfracturing and debonding. Additional studies will be required to better understand degradation phenomena within C-S-H itself.

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The nanogranular behavior of C-S-H at elevated temperatures (up to 700 °C)

Cited by 240 publications

References 27 publications

Nanomechanical properties of C-S-H gel/cement grain interface by using nanoindentation and modulus mapping

Nanomechanical properties of C-S-H gel/cement grain interface by using nanoindentation and modulus mapping

Influence of hardened cement paste content on the water absorption of fine recycled concrete aggregates

Nanomechanical structure-property relations of dynamically loaded reactive powder concrete

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