Competition between Hydration and Carbonation in Hydraulic Lime and Lime-Pozzolana Mortars

2010 ◽  
Vol 133-134 ◽  
pp. 241-246 ◽  
Author(s):  
Özlem Cizer ◽  
Koen Van Balen ◽  
Dionys Van Gemert
Keyword(s):  
Mechanical Properties ◽  
Moisture Content ◽  
Strength Development ◽  
Strength Gain ◽  
Carbonation Reaction ◽  
Hydraulic Lime ◽  
Pozzolanic Material ◽  
Dry Conditions ◽  
Sufficient Strength

A combined reaction of hydration and carbonation takes place in hydraulic lime and lime-pozzolana mortars. Hydration reactions are the first reaction and carbonation of lime is the complementary reaction in the strength gain. Competition between these two reactions can occur in lime-pozzolana mortars if the pozzolanic material has low reactivity with lime, leading to the consumption of lime by carbonation reaction. The degree and the order of these reactions are strongly influenced by the moisture content. Hydration reactions are enhanced under moist conditions while carbonation is delayed. Curing under dry conditions does not sufficiently increase their strength because the hydration reactions are slowed down or even terminated by the full carbonation of lime in lime-pozzolana mortars. The consequence of this on the mechanical properties of the mortars is remarkable while the same impact is not observed in their porosity. Such mortars require moist conditions to ensure sufficient strength development.

scholarly journals Relaxation of ceramic tile stresses generated by fast drying: a kinetic model

2018 ◽  
Author(s):  
J. L. Amorós ◽  
V. Cantavella ◽  
E. Blasco
Keyword(s):  
Mechanical Properties ◽  
Stress Relaxation ◽  
Kinetic Model ◽  
Moisture Content ◽  
Mechanical Strength ◽  
Ceramic Tile ◽  
Drying Process ◽  
Ceramic Tiles ◽  
Relaxation Kinetic ◽  
Dry Conditions

Abstract Unfired tile mechanical properties are very important in the ceramic tile manufacturing process. Inadequate mechanical properties lead to rejects (both in unfired and fired tiles). Unfired tile mechanical strength changes significantly after the tiles exit the industrial dryer. This behaviour can be explained by assuming that the fast-drying process generates stresses in the tile, which subsequently relax. A kinetic model has been derived, based on Maxwell’s viscoelastic elements, which explains the development of dried tile mechanical strength. This increases asymptotically when the dried tiles are stored in dry conditions. However, if tiles adsorb humidity (upon exiting the dryer), tile mechanical strength rises and then decreases. This is the result of two opposing phenomena: stress relaxation raises mechanical strength while the concurrent rise in moisture content lowers mechanical strength. The developed model successfully describes this joint mechanical behaviour. Keywords: ceramic tiles, fast drying, stress relaxation, kinetic model

Effect of Calcium Hydroxide Content on Pozzolanic Reaction of Calcined Clays: Their Mechanical Properties and Microstructures

2021 ◽  
Vol 1034 ◽  
pp. 161-168
Author(s):  
Supaluk Suttikul ◽  
Kanyarat Ano ◽  
Kedsarin Pimraksa
Keyword(s):  
Mechanical Properties ◽  
Calcium Hydroxide ◽  
Clay Minerals ◽  
Pozzolanic Reaction ◽  
Montmorillonite Clay ◽  
Strength Development ◽  
Calcined Clay ◽  
Pozzolanic Material ◽  
Phase Development ◽  
Calcium Aluminosilicate

The research aimed to investigate the effect of calcium hydroxide content on pozzolanic reaction of calcined clays. Pozzolanic reaction of calcined clay was determined in terms of its mechanical properties, phase development and microstructures. Three clay minerals (two kaolinitic clays and kaolinite-montmorillonite clay) were chosen to produce pozzolanic materials via calcination at temperature of 700 °C to allow dehydroxylation of clay minerals. Ratios of calcium hydroxide to calcined clays were varied from 0.1 to 0.5. Mixing water contents or liquid to solid ratios (0.62, 0.75 and 0.80) and curing times (7 and 28 days) were also studied. It was found that calcium aluminosilicate hydrate (stratlingite) could be formed after pozzolanic reactions of all clay minerals. The development of stratlingite agreed with the strength development showing the highest compressive strength at 26 MPa (28 days) when kaolinite-montmorillonite clay was used as pozzolanic material and the ratio of calcium hydroxide to calcined clay was 0.5.

scholarly journals Influence of moisture content on the mechanical properties of selected wood-based composites

BioResources ◽  
2020 ◽  
Vol 15 (3) ◽  
pp. 5503-5513
Author(s):  
Conrad M. Sala ◽  
Eduardo Robles ◽  
Aneta Gumowska ◽  
Anita Wronka ◽  
Grzegorz Kowaluk
Keyword(s):  
Mechanical Properties ◽  
Moisture Content ◽  
Modulus Of Elasticity ◽  
Wood Quality ◽  
Construction Materials ◽  
Modulus Of Rupture ◽  
Slight Reduction ◽  
Furniture Industry ◽  
Different Types ◽  
Dry Conditions

Wood quality depends on many circumstances, as it is sensitive to changing properties, depending on the environment. This work evaluates the influence of moisture content of selected wood-based composites on their basic mechanical properties, i.e., modulus of rupture and modulus of elasticity. The selected panels were divided by application in construction materials and furniture materials, which demand specific conditions during service-life. The increase of moisture content in different types of wood-based panels resulted in a slight reduction of the modulus of rupture and the modulus of elasticity. Boards for use in dry conditions, mainly in the furniture industry, were more sensitive to lowering their modulus of elasticity with higher board moisture content compared with those designed for humid conditions, mainly from the building industry.

scholarly journals Impact of Moisture Content on the Dynamic Failure Energy Dissipation Characteristics of Sandstone

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Aihong Lu ◽  
Shanchao Hu ◽  
Ming Li ◽  
Tianzhu Duan ◽  
Bing Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Elastic Modulus ◽  
Energy Dissipation ◽  
Surface Energy ◽  
Moisture Content ◽  
Rock Masses ◽  
Moisture Contents ◽  
Dry Conditions ◽  
Moisture Conditions

Rockburst frequently occurs in deep underground engineering, which poses a threat to safety and causes economic losses. Water injection into surrounding rock masses is an effective method for preventing rockburst, and the moisture content of rocks is significant for assessing the probability of rockburst. However, the majority of studies focus on the relationship between the macromechanical properties of rock masses under static loads and the moisture content of rock masses and seldom explore the impact of moisture variation (under dynamic loads) on the mechanical properties and energy dissipation. In this paper, the mechanical properties and energy dissipation of sandstone with different moisture contents have been experimentally investigated by the split Hopkinson pressure bar (SHPB) test. The test results indicate that the peak strength, dynamic elastic modulus, and unloading elastic modulus of sandstone in dry conditions are considerably larger than those in moisture conditions, and the three parameters linearly decrease as the moisture content increases from 0% to 2.58%. The distribution law of sandstone fragments with different moisture contents has been investigated by sieving test fragments with different grain sizes of grading sieves. The results show that the percentage of large grain size fragments incrementally decreases, and the percentage of small grain size fragments incrementally increases with moisture contents from 0% to 2.58%. When the moisture content ranges from 2.01%∼2.58%, the fractal dimension linearly increases, which indicates that the higher the moisture content is, the larger the dimension of the broken sandstone is. The calculation results for energy indicate that the sandstone energy attains the peak value with 0% moisture content. When the moisture content ranges from 2.01%∼2.58%, the reflected energy increases, and the transmitted energy and dissipated energy linearly decrease. In addition, the surface energy of the sandstone with different moisture contents has been investigated by converting fragments into spheres with the corresponding size. The results indicate that the smallest surface area of sandstone is obtained in dry conditions, but its surface energy in dry conditions is larger than that in moisture conditions. When the moisture ranges from 0% to 2.58%, due to 3% illite and 2% chlorite clay minerals reacting with different proportions of moisture, the surface areas of sandstone fragments linearly increase and the surface energy of sandstone linearly decreases.

scholarly journals Compressive Strength Gain Behavior and Prediction of Cement-Stabilized Macadam at Low Temperature Curing

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Yongli Xu ◽  
Guang Yang ◽  
Hongyuan Zhao
Keyword(s):  
Compressive Strength ◽  
Low Temperature ◽  
Curing Temperature ◽  
Strength Development ◽  
Construction Process ◽  
Strength Gain ◽  
Estimation Model ◽  
Maturity Method ◽  
Temperature Ranges ◽  
Natural Temperature

For cement-based materials, the curing temperature determines the strength gain rate and the value of compressive strength. In this paper, the 5% cement-stabilized macadam mixture is used. Three indoor controlled temperature curing and one outdoor natural curing scenarios are designed and implemented to study the strength development scenario law of compressive strength, and they are standard temperature curing (20°C), constant low temperature curing (10°C), day interaction temperature curing (varying from 6°C to 16°C), and one outdoor natural temperature curing (in which the air temperature ranges from 4°C to 20°C). Finally, based on the maturity method, the maturity-strength estimation model is obtained by using and analyzing the data collected from the indoor tests. The model is proved with high accuracy based on the validated results obtained from the data of outdoor tests. This research provides technical support for the construction of cement-stabilized macadam in regions with low temperature, which is beneficial in the construction process and quality control.

scholarly journals Symmetric Nature of Stress Distribution in the Elastic-Plastic Range of Pinus L. Pine Wood Samples Determined Experimentally and Using the Finite Element Method (FEM)

Symmetry ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 39
Author(s):  
Łukasz Warguła ◽  
Dominik Wojtkowiak ◽  
Mateusz Kukla ◽  
Krzysztof Talaśka
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Stress Distribution ◽  
Moisture Content ◽  
Tool Geometry ◽  
Wood Fibers ◽  
Data Set ◽  
Plastic Deformations ◽  
Pine Wood ◽  
Elastic Plastic

This article presents the results of experimental research on the mechanical properties of pine wood (Pinus L. Sp. Pl. 1000. 1753). In the course of the research process, stress-strain curves were determined for cases of tensile, compression and shear of standardized shapes samples. The collected data set was used to determine several material constants such as: modulus of elasticity, shear modulus or yield point. The aim of the research was to determine the material properties necessary to develop the model used in the finite element analysis (FEM), which demonstrates the symmetrical nature of the stress distribution in the sample. This model will be used to analyze the process of grinding wood base materials in terms of the peak cutting force estimation and the tool geometry influence determination. The main purpose of the developed model will be to determine the maximum stress value necessary to estimate the destructive force for the tested wood sample. The tests were carried out for timber of around 8.74% and 19.9% moisture content (MC). Significant differences were found between the mechanical properties of wood depending on moisture content and the direction of the applied force depending on the arrangement of wood fibers. Unlike other studies in the literature, this one relates to all three stress states (tensile, compression and shear) in all significant directions (anatomical). To verify the usability of the determined mechanical parameters of wood, all three strength tests (tensile, compression and shear) were mapped in the FEM analysis. The accuracy of the model in determining the maximum destructive force of the material is equal to the average 8% (for tensile testing 14%, compression 2.5%, shear 6.5%), while the average coverage of the FEM characteristic with the results of the strength test in the field of elastic-plastic deformations with the adopted ±15% error overlap on average by about 77%. The analyses were performed in the ABAQUS/Standard 2020 program in the field of elastic-plastic deformations. Research with the use of numerical models after extension with a damage model will enable the design of energy-saving and durable grinding machines.

scholarly journals Mechanical Properties of Cement-Treated Soil Mixed with Cellulose Nanofibre

2021 ◽  
Vol 11 (14) ◽  
pp. 6425
Author(s):  
Hidenori Takahashi ◽  
Shinya Omori ◽  
Hideyuki Asada ◽  
Hirofumi Fukawa ◽  
Yusuke Gotoh ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Geotechnical Engineering ◽  
Strength Development ◽  
Soft Ground ◽  
Wood Cellulose ◽  
Treated Soil ◽  
Made In ◽  
Cement Treatment

Cellulose nanofibre (CNF), a material composed of ultrafine fibres of wood cellulose fibrillated to nano-order level, is expected to be widely used because of its excellent properties. However, in the field of geotechnical engineering, almost no progress has been made in the development of techniques for using CNFs. The authors have focused on the use of CNF as an additive in cement treatment for soft ground, where cement is added to solidify the ground, because CNF can reduce the problems associated with cement-treated soil. This paper presents the results of a study on the method of mixing CNF, the strength and its variation obtained by adding CNF, and the change in permeability. CNF had the effect of mixing the cement evenly and reducing the variation in the strength of the treated soil. The CNF mixture increased the strength at the initial age but reduced the strength development in the long term. The addition of CNF also increased the flexural strength, although it hardly changed the permeability.

scholarly journals Effect of Moisture Content on the Processing and Mechanical Properties of a Biodegradable Polyester

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1616
Author(s):  
Vincenzo Titone ◽  
Antonio Correnti ◽  
Francesco Paolo La Mantia
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Moisture Content ◽  
Mechanical Testing ◽  
Hydrolytic Degradation ◽  
Slight Reduction ◽  
Biodegradable Polyester ◽  
Molding Process ◽  
Elongation At Break ◽  
Effect Of Moisture

This work is focused on the influence of moisture content on the processing and mechanical properties of a biodegradable polyester used for applications in injection molding. The pellets of the biodegradable polyester were exposed under different relative humidity conditions at a constant temperature before being compression molded. The compression-molded specimens were again placed under the above conditions before the mechanical testing. With all these samples, it is possible to determine the effect of moisture content on the processing and mechanical properties separately, as well as the combined effect of moisture content on the mechanical properties. The results obtained showed that the amount of absorbed water—both before processing and before mechanical testing—causes an increase in elongation at break and a slight reduction of the elastic modulus and tensile strength. These changes have been associated with possible hydrolytic degradation during the compression molding process and, in particular, with the plasticizing action of the moisture absorbed by the specimens.

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