Performance of Lime-Metakaolin Pastes and Mortars in Two Curing Conditions Containing Kaolin Wastes

2015 ◽  
Vol 668 ◽  
pp. 419-432 ◽  
Author(s):  
Aline Figueirêdo Nóbrega de Azerêdo ◽  
Givanildo Azeredo ◽  
Arnaldo Manoel Pereira Carneiro
Keyword(s):  
Hydrated Lime ◽  
Microstructural Characteristics ◽  
Curing Conditions ◽  
Pozzolanic Material ◽  
Cement Mortars ◽  
Lime Mortars ◽  
Moist Environment ◽  
Hardened State ◽  
Hydrated Products ◽  
Hardened Properties

Many works have shown that metakaolin is very good pozzolanic material for using in lime mortars and Portland cement mortars. Alternatively, many studies also have shown that kaolin wastes, after some treatment, can become a high quality pozzolans. Most of these studies have discussed about the microstructural characteristics and hardened properties of pastes, mortars or concretes mixes containing metakaolin or kaolin wastes cured in moist environment. In this work pastes and mortars made of metakaolin and hydrated lime (L-MK), which the metakaolin was obtained from the kaolin production waste, were assessed in their hardened state. Two curing conditions were considered: dry and moist environment; and three ages of curing (28, 90 and 180 days) were studied. Pastes were assessed by XRD and TG/DTG. In pastes according to the XRD and TG/DTG results, the main hydrated products found were strätlingite, in moist curing, and monocarboaluminate, in dry curing. Properties like flexural and compressive strengths, water absorbed capillarity and loss mass variation were studied in mortars. The results showed that mortars in dry curing presented lower strengths than one in moist curing. In moist curing mortars presented compressive strength values around 12 MPa and in dry curing this value reached 6 MPa. This fact indicate that the strätlingite maybe is responsible for the high strengths in mortars in moist curing when compares with the strengths of mortars cured in dry environment. Further the results showed that mortars in dry curing presented higher water absorbed and mass loss variation than mortars in moist curing.

Hardened Properties of Lime Based Mortars Produced from Kaolin Wastes

2014 ◽  
Vol 600 ◽  
pp. 282-296 ◽  
Author(s):  
Aline Figueirêdo Nóbrega de Azerêdo ◽  
Arnaldo Manoel Pereira Carneiro ◽  
Givanildo Alves de Azeredo ◽  
Mauro Sardela
Keyword(s):  
Thermal Analysis ◽  
Microstructural Analysis ◽  
Construction Materials ◽  
Inert Material ◽  
X Rays ◽  
Historical Buildings ◽  
Microstructural Characteristics ◽  
River Sand ◽  
Lime Mortars ◽  
Hardened Properties

Many studies have been developed about the use of wastes as construction materials. The higher volume of waste generated by many types of industries has caused many environmental problems. Most of these wastes have not been placed in adequate sites, or even been reused. In Brazil the industries that produces kaolin generates a lot of wastes. Studies have been carried out on the use of kaolin wastes as replacement material for Portland cement concretes and mortars; and only few ones have studied it in hydraulic mortars for restoration of historical buildings. In this work kaolin wastes were studied as pozzolanic and inert material in lime mortars. Two lime/metakaolin ratios and different proportions of kaolin wastes as replacement of river sand were studied. Hardened properties of these mortars like compressive and tensile strength and water absorbed by capillarity were evaluated up to 180 days of curing. Microstructural characteristics also were assessed using thermal analysis (TG/DTG) and x-rays diffraction (XRD). Some mortars presented the highest strengths at 90 days of curing, and at 180 days their resistances dropped. The major phases found by microstructural analysis were monocarboaluminate (C4ACH11) and calcium carbonate (CaCO3).

scholarly journals Lime-based mortars with various binder composition: characterization and freeze-thaw resistance assessment

2021 ◽  
Vol 1205 (1) ◽  
pp. 012009
Author(s):  
D Janotova ◽  
Z Slizkova
Keyword(s):  
Outer Part ◽  
Testing Procedure ◽  
Lime Mortar ◽  
Curing Conditions ◽  
Binder Component ◽  
Hydraulic Binder ◽  
Lime Mortars ◽  
Hardened State ◽  
Binder Composition ◽  
Mixing Water

Abstract The study focused on lime mortars with different lime binder types regarding the frost attack effects on their microstructure and mechanical characteristics. The performances of studied mortars in hardened state was significantly influenced by the amount of mixing water and by curing conditions. Inhomogeneous microstructure was observed inside the 360 days old specimens with dimensions 40 × 40 × 160 mm in the case of all lime mortars types. The different state of the binder hardening with respect to various distances from the specimen surface and the different behaviour of matured outer part and immature inner part of lime mortar specimens influenced performed tests and reflected in all results. After 10 and 20 freeze cycles, respectively, the compressive strength of all lime mortar specimens with the hydraulic binder component increased, indicating a beneficial effect of the water on the hydration previously unreacted hydraulic binders. On the other hand, the flexural strength of the frost-aged specimens decreased significantly, indicating the drastic procedure of the test performed concerning lime mortars characteristics, especially when the pure air lime binder was used. Improvement of the testing procedure especially for lime mortars, which are characterized by slow hardening, was recommended.

scholarly journals Effect of Type of Curing and Metakaolin Replacement on Air Lime Mortars for the Durability of Masonries

2021 ◽  
Vol 6 (10) ◽  
pp. 143
Author(s):  
João Monteiro ◽  
Vitor Silva ◽  
Paulina Faria
Keyword(s):  
Relative Humidity ◽  
Atlantic Ocean ◽  
Mechanical Performance ◽  
Early Stage ◽  
Mechanical Parameters ◽  
Curing Conditions ◽  
Physical Chemical ◽  
Lime Mortars ◽  
Hardened Properties

The interest in restoration and maintenance of old masonries towards their durability is nowadays combined with the concept of sustainability and the need to implement more suitable materials for building heritage interventions. This has led to the importance of having a better knowledge of air lime mortars, namely on the effect of pozzolanic additions, curing conditions and evolution at early stages. This study consisted in the characterization of mortars based on hydrated air lime and sand, with 1:2 (lime:sand) volumetric composition, with different weight percentages of substitution of lime by metakaolin (Mk): 0%, 10% and 20%. Mortar prisms were analyzed in three different curing environments: maritime (by the Atlantic Ocean), in laboratory humidity (95 ± 5% relative humidity, RH) and standard (65 ± 5% RH) conditioning. Tests were conducted to evaluate fresh and hardened properties of mortars, considering physical, chemical and mechanical performance at 28, 90 and 180 days. Results showed the viability of applying air lime-Mk mortars with curing conditions similar to the tested ones. In the standard curing, the mortar with 20% Mk revealed advantages in mechanical parameters. Concerning the behaviour towards water, improvements were shown at an early stage with the humid curing, while maritime curing benefited its behaviour for at least up to 6 months.

Measurement of strength and microstructural characteristics of epoxypolimers cured by thermal and microwave methods

2020 ◽  
pp. 35-41
Author(s):  
E. V. Matveev ◽  
A. V. Mamontov ◽  
A. I. Gajdar ◽  
B. A. Lapshinov ◽  
A. N. Vinogradov
Keyword(s):  
Microwave Field ◽  
Epoxy Polymer ◽  
Local Deformation ◽  
Test Method ◽  
Microstructural Characteristics ◽  
Curing Conditions ◽  
Secondary Cracks ◽  
Curing Methods ◽  
Cracks Propagation ◽  
The Relationship

In this work, we studied the strength parameters, fractographic patterns, and the microstructure of epoxy polymer samples cured both by thermal and microwave methods at various temperature, power, and time conditions. The dependence of strength on curing conditions is determined using the tensile test method. To achieve maximum strength for both curing methods optimum conditions were found. A comparative fractographic analysis of microwave and thermal cured samples fractures having similar strength characteristics was carried out by electron microscopy. It was found that microwave field curing leads to the globules size increase in the cured epoxy polymer and an increase in the number of nanopores in the material. Plastic samples local deformation is also more pronounced during fracture, which leads to a greater difference of the main and secondary cracks propagation velocities ratio. The relationship between the studied samples optical density in the wavelength range from 360 to 2500 nm and the parameters of both curing methods (microwave and thermal) was established.

Fresh and hardened state behaviour of aerial lime mortars with superplasticizer

2019 ◽  
Vol 225 ◽  
pp. 1127-1139 ◽  
Author(s):  
Bruna Silva ◽  
Ana Paula Ferreira Pinto ◽  
Augusto Gomes ◽  
António Candeias
Keyword(s):  
Lime Mortars ◽  
State Behaviour ◽  
Hardened State

scholarly journals Quantitative Analysis of CO2 Uptake and Mechanical Properties of Air Lime-Based Materials

Energies ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2903 ◽  
Author(s):  
Sung-Hoon Kang ◽  
Yang-Hee Kwon ◽  
Juhyuk Moon
Keyword(s):  
Portland Cement ◽  
Silica Fume ◽  
Co2 Concentration ◽  
Hydrated Lime ◽  
Cement Industry ◽  
Raw Material ◽  
Co2 Uptake ◽  
Carbonation Reaction ◽  
Lime Mortar ◽  
Curing Conditions

In the cement industry, utilization of a sustainable binder that has a lower energy consumption and carbon dioxide (CO2) emission than Portland cement is becoming increasingly important. Air lime is a binder that hardens by absorbing CO2 from the atmosphere, and its raw material, hydrated lime, is manufactured at a lower temperature (around 900 °C) than cement (around 1450 °C). In this study, the amount and rate of CO2 uptake by air lime-based materials are quantitatively evaluated under ambient curing conditions of 20 °C, 60% relative humidity, and 0.04% CO2 concentration. In addition, the effects of the water-to-binder ratio (w/b) and silica fume addition on the material properties of the air lime mortar, such as strength, weight change, carbonation depth, and pore structure, are investigated. Unlike hydraulic materials, such as Portland cement, the air lime mortar did not set and harden under a sealed curing condition, however, once exposed to dry air, the mortar began to harden by absorbing CO2. During the first week, most of the internal water evaporated, thus, the mortar weight was greatly reduced. After that, however, both the weight and the compressive strength consistently increased for at least 180 days due to the carbonation reaction. Based on the 91-day properties, replacing 10% of hydrated lime with silica fume improved the compressive and flexural strengths by 27% and 13% respectively, whereas increasing the w/b from 0.4 to 0.6 decreased both strengths by 29% due to the increased volume of the capillary pores. The addition of silica fume and the change in the w/b had no significant impact on the amount of CO2 uptake, but these two factors were effective in accelerating the CO2 uptake rate before 28 days. Lastly, the air lime-based material was evaluated to be capable of recovering half of the emitted CO2 during the manufacture of hydrated lime within 3 months.

scholarly journals Ultrasonic Pulse Velocity—Compressive Strength Relationship for Portland Cement Mortars Cured at Different Conditions

Crystals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 133 ◽  
Author(s):  
Esteban Estévez ◽  
Domingo Alfonso Martín ◽  
Cristina Argiz ◽  
Miguel Ángel Sanjuán
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Internal Quality ◽  
Curing Conditions ◽  
Linear Relationships ◽  
Cement Mortars ◽  
Strength Relationship

The purpose of this paper is to establish some correlations between the main technical parameter with regard to the cement-based materials technology, the 28-day compressive strength, and ultrasonic pulse velocity of standard mortar samples cured at three different conditions—(i) under water at 22 °C; (ii) climatic chamber at 95% RH and 22 °C; (iii) lab ambient, 50% RH, and 22 °C—and after five curing periods of 1, 2, 7, 14, and 28 days. Good correlations for each curing conditions were obtained. All the positive linear relationships showed better R2 than exponential ones. These findings may promote the use of ultrasonic pulse velocity for the estimation of the 28-day compressive strength of standard Portland cement samples within the factory internal quality control.

Evaluation of Mechanical Behavior and Microstructural Characteristics of Photocatalytic Concretes to Be Used as Pavement Blocks

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
João Victor Staub de Melo ◽  
Glicério Trichês
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Mechanical Behavior ◽  
Tio2 Nanoparticles ◽  
Modulus Of Elasticity ◽  
Microstructural Characteristics ◽  
State Tests ◽  
Fresh State ◽  
Hardened State ◽  
Microstructural Behavior

This paper reports the results obtained in a study on the effect of the addition of TiO2 nanoparticles on the mechanical properties and microstructural characteristics of photocatalytic concretes. In the hardened state, tests to determine the compressive strength and modulus of elasticity were carried out. Also, microstructural aspects of the samples were investigated. In the fresh state, the influence of the addition of TiO2 on the concrete compaction and conduction calorimetry curves was evaluated. The results obtained indicated a better mechanical and microstructural behavior of concrete with addition of TiO2.

Non-Destructive Tests as Durability Indicators in Cement Mortars with Pozzolanic Substitutions

2017 ◽  
Vol 902 ◽  
pp. 9-13
Author(s):  
Rosalía Ruiz Ruiz ◽  
Elia Mercedes Alonso Guzmán ◽  
Wilfrido Martínez Molina ◽  
Hugo Luis Chávez García ◽  
Judith Alejandra Velázquez Perez
Keyword(s):  
Mechanical Characteristics ◽  
Ultrasonic Pulse Velocity ◽  
Good Alternative ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Cement Industry ◽  
Capillary Absorption ◽  
Pozzolanic Material ◽  
Cement Mortars ◽  
Non Destructive

Cement industry is responsible of 5-7% of CO2 emissions to the atmosphere. This is preoccupant because this is one of the greenhouse effect gases which cause global warming. Pozzolanic material incorporation in cement mortars elaboration represents a good alternative to partially substitute cement, since its chemical composition could contribute to improvement of its durability and mechanical characteristics. In this research, mortars with pozzolanic substitutions are evaluated through non-destructive tests as: capillary absorption, electrical resistivity, and ultrasonic pulse velocity to the age of 1000 days. The results suggested that the incorporation of pozzolanic material as partial substitutes of Portland cement increases the mortars properties mainly in substitutions of CBC 20%, PN 10, and 30%.

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