scholarly journals The influence of curing temperature, plastic additives and polypropylene fibers on the mechanical behaviour of cementitious materials

2020 ◽  
Vol 150 ◽  
pp. 02012
Author(s):  
Mohammed Aqil ◽  
Lahcen Bahi ◽  
Latifa Ouadif ◽  
Siham Belhaj ◽  
Raounak Edderkaoui
Keyword(s):  
Compressive Strength ◽  
Mechanical Behaviour ◽  
Mechanical Performance ◽  
Cementitious Materials ◽  
Curing Temperature ◽  
Polypropylene Fibers ◽  
Hydration Kinetics ◽  
Degree Of Hydration ◽  
History Of ◽  
Kinetics Of

An experimental company was carried out to better understand the influence of curing temperature on the mechanical behaviour of cementitious materials, particularly compressive strength, the study focused on two types of mortars, the first containing polypropylene fibers while the second contains a proportion of PVC-type plastic grains from industrial waste, the hydration kinetics of the different components of the formulated mortar has been characterized by the isothermal calorimetric test, thus a history of the hydration degrees has been established, Afterwards, an attempt was made to correlate the compressive strength with the evolution of the degree of hydration for the different formulations, based on the results obtained, it is clearly observable that the compressive strength evolves with the degree of hydration and that the specimen containing the polypropylene fibers has the best mechanical performance with respect to compression.

scholarly journals Influence of Ultrasonication of Functionalized Carbon Nanotubes on the Rheology, Hydration, and Compressive Strength of Portland Cement Pastes

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5248
Author(s):  
Laura Silvestro ◽  
Artur Ruviaro ◽  
Geannina Lima ◽  
Paulo de Matos ◽  
Afonso R. G. de Azevedo ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Compressive Strength ◽  
Portland Cement ◽  
Mechanical Performance ◽  
Isothermal Calorimetry ◽  
Hydration Kinetics ◽  
Cement Pastes ◽  
Degree Of Hydration ◽  
Vis Spectroscopy ◽  
Localized Defects

The functionalization process usually increases the localized defects of carbon nanotubes (CNT). Thus, the ultrasonication parameters used for dispersing non-functionalized CNT should be carefully evaluated to verify if they are adequate in dispersing functionalized CNT. Although ultrasonication is widely used for non-functionalized CNT, the effect of this dispersing process of functionalized CNT has not been thoroughly investigated. Thus, this work investigated the effect of ultrasonication on functionalized CNT + superplasticizer (SP) aqueous dispersions by ultraviolet-visible (UV-Vis) spectroscopy, dynamic light scattering (DLS), and Fourier transform infrared spectroscopy (FTIR). Furthermore, Portland cement pastes with additions of 0.05% and 0.1% CNT by cement weight and ultrasonication amplitudes of 0%, 50% and 80% were evaluated through rheometry, isothermal calorimetry, compressive strength at 1, 7 and 28 days, X-ray diffraction (XRD), and thermogravimetric analysis (TGA). FTIR results from CNT + SP dispersions indicated that ultrasonication may negatively affect SP molecules and CNT graphene structure. The increase in CNT content and amplitude of ultrasonication gradually increased the static and dynamic yield stress of paste but did not significantly affect its hydration kinetics. Compressive strength results indicated that the optimum CNT content was 0.05% by cement weight, which increased the strength of composite by up to 15.8% compared with the plain paste. CNT ultrasonication neither increases the degree of hydration of cement nor the mechanical performance of composite when compared with mixes containing unsonicated CNT. Overall, ultrasonication of functionalized CNT is not efficient in improving the fresh and hardened performance of cementitious composites.

scholarly journals Use of Treated Non-Ferrous Metallurgical Slags as Supplementary Cementitious Materials in Cementitious Mixtures

2021 ◽  
Vol 11 (9) ◽  
pp. 4028
Author(s):  
Asghar Gholizadeh Vayghan ◽  
Liesbeth Horckmans ◽  
Ruben Snellings ◽  
Arne Peys ◽  
Priscilla Teck ◽  
...  
Keyword(s):  
Mechanical Performance ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Partial Replacement ◽  
Strength Development ◽  
Supplementary Cementitious Material ◽  
Performance Requirements ◽  
Metallurgical Slags ◽  
Leaching Behaviour ◽  
Kinetics Of

This research investigated the possibility of using metallurgical slags from the copper and lead industries as partial replacement for cement. The studied slags were fayalitic, having a mainly ferro-silicate composition with minor contents of Al2O3 and CaO. The slags were treated at 1200–1300 °C (to reduce the heavy metal content) and then granulated in water to promote the formation of reactive phases. A full hydration study was carried out to assess the kinetics of reactions, the phases formed during hydration, the reactivity of the slags and their strength activity as supplementary cementitious material (SCM). The batch-leaching behaviour of cementitious mixtures incorporating treated slags was also investigated. The results showed that all three slags have satisfactory leaching behaviour and similar performance in terms of reactivity and contribution to the strength development. All slags were found to have mediocre reactivity and contribution to strength, especially at early ages. Nonetheless, they passed the minimum mechanical performance requirements and were found to qualify for use in cement.

scholarly journals Cement-Based Renders Manufactured with Phase-Change Materials: Applications and Feasibility

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Luigi Coppola ◽  
Denny Coffetti ◽  
Sergio Lorenzi
Keyword(s):  
Compressive Strength ◽  
Phase Change ◽  
Phase Change Materials ◽  
Residential Buildings ◽  
Setting Time ◽  
Drying Shrinkage ◽  
Hydration Kinetics ◽  
Mechanical Performances ◽  
Entrapped Air ◽  
Kinetics Of

The paper focuses on the evaluation of the rheological and mechanical performances of cement-based renders manufactured with phase-change materials (PCM) in form of microencapsulated paraffin for innovative and ecofriendly residential buildings. Specifically, cement-based renders were manufactured by incorporating different amount of paraffin microcapsules—ranging from 5% to 20% by weight with respect to binder. Specific mass, entrained or entrapped air, and setting time were evaluated on fresh mortars. Compressive strength was measured over time to evaluate the effect of the PCM addition on the hydration kinetics of cement. Drying shrinkage was also evaluated. Experimental results confirmed that the compressive strength decreases as the amount of PCM increases. Furthermore, the higher the PCM content, the higher the drying shrinkage. The results confirm the possibility of manufacturing cement-based renders containing up to 20% by weight of PCM microcapsules with respect to binder.

scholarly journals Influence of Partial Replacement of Micro-Silica by Fly-Ash on Strength Properties of Reactive Powder Concrete

2020 ◽  
Vol 9 (3) ◽  
pp. 2932-2937
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Fly Ash ◽  
Mechanical Performance ◽  
Cementitious Materials ◽  
Partial Replacement ◽  
Reactive Powder Concrete ◽  
Experimental Investigations ◽  
Reactive Powder ◽  
Micro Silica

Reactive powder concrete (RPC) is the ultra-high strength concrete made by cementitious materials like silica fumes, cement etc. The coarse aggregates are completely replaced by quartz sand. Steel fibers which are optional are added to enhance the ductility. Market survey has shown that micro-silica is not so easily available and relatively costly. Therefore an attempt is made to experimentally investigate the reduction of micro-silica content by replacing it with fly-ash and mechanical properties of modified RPC are investigated. Experimental investigations show that compressive strength decreases gradually with addition of the fly ash. With 10 per cent replacement of micro silica, the flexural and tensile strength showed 40 and 46 per cent increase in the respective strength, though the decrease in the compressive strength was observed to be about 20 per cent. For further percentage of replacement, there was substantial drop in compressive, flexural as well as tensile strength. The experimental results thereby indicates that utilisation of fly-ash as a partial replacement to micro silica up to 10 per cent in RPC is feasible and shows quite acceptable mechanical performance with the advantage of utilisation of fly-ash in replacement of micro-silica.

scholarly journals Influence of Glass Powder on Hydration Kinetics of Composite Cementitious Materials

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Xiaolin Chang ◽  
Xinping Yang ◽  
Wei Zhou ◽  
Guoshuai Xie ◽  
Shuhua Liu
Keyword(s):  
Glass Powder ◽  
Isothermal Calorimetry ◽  
Cementitious Materials ◽  
Heat Emission ◽  
Hydration Heat ◽  
Hydration Kinetics ◽  
Period Increase ◽  
Acceleration Period ◽  
Boundary Reaction ◽  
Kinetics Of

The influence of glass powder (GP) on hydration kinetics of composite cementitious materials has been investigated by isothermal calorimetry test and hydration kinetics methods in this paper. The hydration heat emission rate and hydration heat decrease gradually while the induction and acceleration period increase with the increase of GP content. According to Krstulovic-Dabic model, the hydration process of composite cementitious materials containing GP is controlled by a variety of complicated reaction mechanisms, which can be divided into three periods: nucleation and crystal growth (NG), phase boundary reaction (I), and diffusion (D). The NG and I process are shortened after incorporating GP.

scholarly journals Mechanical Performance and Microstructure of Ultra-High-Performance Concrete Modified by Calcium Sulfoaluminate Cement

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Meimei Song ◽  
Chuanlin Wang ◽  
Ying Cui ◽  
Qiu Li ◽  
Zhiyang Gao
Keyword(s):  
Compressive Strength ◽  
High Performance ◽  
Mechanical Performance ◽  
High Performance Concrete ◽  
Autogenous Shrinkage ◽  
Ultra High Performance Concrete ◽  
Maximum Heat ◽  
Degree Of Hydration ◽  
Calcium Sulfoaluminate ◽  
Shrinkage Property

High autogenous shrinkage property is one of the disadvantages of ultra-high-performance concrete (UHPC), which may induce early age cracking and threaten the safety of concrete structure. In the present study, different dosages of calcium sulfoaluminate (CSA) cement were added in UHPC as an effective expansive binder. Hydration mechanism, autogenous shrinkage property, and compressive strength of UHPC were carried out to investigate the effect of CSA addition on the mechanical properties of UHPC. Scanning electron microscopy was also employed to characterize the intrinsic microstructural reasons relating to the changes in macroproperties. Based on the XRD diagram, increasing formation of ettringite and Ca(OH)2 can be found with increasing CSA content up to 15%. In the heat flow results of UHPC with 10% CSA addition, the maximum heat release increases to 2.6 mW/g, which is 8.3% higher than the reference UHPC, suggesting a higher degree of hydration with CSA addition. The results in autogenous shrinkage show that CSA expansion agent plays a significantly beneficial role in improving the autogenous shrinkage of UHPC. The corresponding autogenous shrinkage of UHPC is −59.66 μ ε , −131.11 μ ε , and −182.31 μ ε , respectively, at 7 d with 5%, 10%, and 15% addition, which is 108%, 117%, and 123% reduction compared to the reference specimen without CSA. In terms of compressive strength, UHPC with 5%, 10%, 15%, and 20% CSA addition has 10.5%, 17.4%, 30.2%, and 22.1% higher compressive strength than that for the reference UHPC at 28 d. Microstructural study shows that there is an extremely dense microstructure in both the bulk matrix and interfacial transition zone of UHPC with 10% CSA addition, which can be attributed to the higher autogenous shrinkage property and can therefore result in higher mechanical performance.

scholarly journals Hydration Kinetics of Portland Cement–Silica Fume Binary System at Low Temperature

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3896 ◽  
Author(s):  
Yao Li ◽  
Yonggang Deng ◽  
Runqing Liu
Keyword(s):  
Binary System ◽  
Low Temperature ◽  
Portland Cement ◽  
Silica Fume ◽  
Rate Constant ◽  
Reaction Order ◽  
Cementitious Materials ◽  
Hydration Kinetics ◽  
K Value ◽  
Kinetics Of

Portland cement–silica fume binary cementitious materials are widely used in engineering construction and have been investigated from micro- to macroscopic aspects. However, the theoretical background on the hydration kinetics of the binary system has not been sufficiently covered in the literature. In this study, the hydration dynamic characteristics of the Portland cement–silica fume binary system curing at low temperature were investigated. Hydration kinetics equations were optimized and a hydration model followed by a computer program was developed to calculate the reaction rate constant K and the reaction order n. This model presented that the hydration process of the binary system at low temperature could be divided into three stages, namely, nucleation and growth (NG), interactions at phase boundaries (I), and diffusion (D). The n values for the binary system varied in the range of 1.2 to 1.6, indicating that the hydration of the binary system at low temperature was a complex elementary reaction. Silica fume can reduce the total heat at the later stage of the hydration and the reaction order n, but increase the heat flow at the accelerating stage and the hydration rate constant K. Low temperature prolonged the hydration induction period, decreased and delayed the secondary exothermic peak, as well as reduced the n and K value.

Stabilization of Sulfate-Containing Soil by Cementitious Mixtures Mechanical Properties

2003 ◽  
Vol 1837 (1) ◽  
pp. 12-19 ◽  
Author(s):  
Lan Wang ◽  
Amitava Roy ◽  
Roger K. Seals ◽  
John B. Metcalf
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Cementitious Materials ◽  
Curing Temperature ◽  
Type I ◽  
Size Fractions ◽  
Granulated Blast Furnace Slag ◽  
Local Parish ◽  
Stabilized Soil ◽  
North Louisiana

Winn Rock (CaSO4) gravel from a quarry in Winn Parish in north Louisiana was used extensively as a surface course for local parish roads. Stabilization of these roads with Type I portland cement followed by an overlay of asphaltic concrete resulted in heaving. A study was undertaken to investigate the cause or causes of the expansion as well as to identify an alternate means of stabilization. Specimens of representative soil from the affected area were stabilized in the laboratory using various cementitious materials and were cured using a variety of methods. The mix contained 5% to 20% cementitious material. The cementitious materials were Type I portland cement, lime, and supplementary cementing materials such as granulated blast furnace slag (BFS), Class C fly ash (CFA), silica fume, and an amorphous silica (AS). The unconfined compressive strength of the stabilized soil was determined. The effect of size fractions other than the gravel on the expansion was assessed, and the expansion of the specimens over time was monitored. The cement and BFS mixtures almost doubled the compressive strength of the specimens compared with portland cement alone. The finer size fractions were responsible for expansion. The magnitude of expansion was directly proportional to the amount of Type I portland cement, the amount of available moisture, and the curing temperature. Replacement of a part of the portland cement by BFS significantly reduced the amount of expansion even at the highest moisture content. No expansion was detected when CFA and AS partially replaced the cement.

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