STEAM CURING OF PORTLAND CEMENT MORTARS. A NEW CRYSTALLINE SUBSTANCE.: (Preliminary Paper)

1929 ◽  
Vol 1 (2) ◽  
pp. 148-154 ◽  
Author(s):  
T. Thorvaldson ◽  
G. R. Shelton
Keyword(s):  
Portland Cement ◽  
Great Increase ◽  
Chemical Properties ◽  
Hydrated Lime ◽  
Crystalline Material ◽  
Saturated Steam ◽  
Crystalline Substance ◽  
Steam Curing ◽  
Cement Mortars ◽  
The Stability

The steam-curing of Portland Cement Mortars in saturated steam at 100°, 125°, 150°, 175° and 200 °C. was studied both as to variations in the tensile strength of 2-day and 28-day mortar briquets and as to the changes which occurred in the crystalline matter in the cement. The rate of hydration of the cement, as shown by the disappearance of the original crystalline material, increased with the temperature of the saturated steam. Crystals of calcium hydroxide appeared almost at once, but after reaching a maximum decreased again in amount. At the same time, a new crystalline product appeared and increased in quantity as the amount of hydrated lime decreased. Some of the chemical properties of the new crystals are given. The stability of the new crystals when exposed to solutions of sulphates indicates that the great increase in the resistance of Portland cement mortars to alkali action produced by steam-curing is connected with the production of this crystalline material.

STUDIES ON THE ACTION OF SULPHATES ON PORTLAND CEMENT: II. STEAM-CURING OF PORTLAND CEMENT MORTAR AND CONCRETE AS A REMEDY FOR SULPHATE (ALKALI) ACTION

1929 ◽  
Vol 1 (4) ◽  
pp. 359-384 ◽  
Author(s):  
T. Thorvaldson ◽  
V. A. Vigfusson ◽  
D. Wolochow
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Portland Cement ◽  
Laboratory Study ◽  
Cement Mortar ◽  
Steam Curing ◽  
Cement Mortars ◽  
Sodium Magnesium ◽  
The Stability

A study was made of the effect of steam-curing at various temperatures between 50° and 200 °C. on the resistance of Portland cement mortars to the action of solutions of the sulphates of sodium, magnesium and calcium. The methods used consisted in comparing the expansion of steam-cured and untreated mortar specimens during exposure to the solutions, and in determining the changes in the tensile strength of the more resistant mortars after long periods of exposure.A laboratory study of steam-curing as a remedy for the action of sulphates ("alkali") on Portland cement mortars, was made by determining the effect on the stability of the mortar as indicated by changes in volume and in tensile strength on exposure to sulphate solutions at 21 °C. The effect of steam-curing on the tensile and compressive strength of mortars and concrete was also studied.

Effect of hydrated lime on efflorescence formation

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Diogo Henrique de Bem ◽  
Priscila Ongaratto Trentin ◽  
Ronaldo A. Medeiros-Junior
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Design Methodology ◽  
Hydrated Lime ◽  
Content Type ◽  
Mercury Intrusion ◽  
Lime Content ◽  
Cement Mortars ◽  
Cement Based Materials ◽  
Historical Heritage

PurposeEfflorescence formation is very common in cement-based materials. In the case of mortar, efflorescence is more studied when only Portland cement is used as a binder. However, the repair of historical heritage, as well as the construction system of some countries, usually uses mortars composed of hydrated lime and Portland cement. This study aims to determine the influence of the hydrated lime content on the incidence of efflorescence in mortars.Design/methodology/approachMortars with 0%, 50%, and 100% lime/cement ratio were studied, using three different methods to accelerate efflorescence formation. The surface area of mortars affected by efflorescence was quantified by analysis using image software. Also, analysis of mercury intrusion porosity test, flexural tensile, compressive strength, absorption of water by capillarity, porosity, XRD and TGA was performed.FindingsMore efflorescence in mortars with a higher amount of lime in their composition was observed. The results show that the increase in the lime content reduces the flexural tensile and the compressive strength and increased the absorption of water by capillarity and the porosity of the mortars. The material formed by the efflorescence was calcium carbonate, proven by microstructural tests.Originality/valueThe results of greater efflorescence formation in mortars with lime are important to alert users who apply this type of material. Some type of protection must be done more rigorously for lime-cement mortars, especially concerning contact with water, since efflorescence tends to be faster for this type of material.

Synthesis and application of methylcellulose extracted from waste newspaper in CPV-ARI Portland cement mortars

2010 ◽  
pp. n/a-n/a
Author(s):  
Geandre de Carvalho Oliveira ◽  
Guimes Rodrigues Filho ◽  
Júlia Graciele Vieira ◽  
Rosana M. Nascimento De Assunção ◽  
Carla da Silva Meireles ◽  
...  
Keyword(s):  
Portland Cement ◽  
Cement Mortars

Studies on Polyaniline: Polyethyleneterephthalate Films

2006 ◽  
Vol 111 ◽  
pp. 99-102 ◽  
Author(s):  
A.A. Ahmed ◽  
Faiz Mohammad
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Arrhenius Equation ◽  
Great Increase ◽  
Thermooxidative Stability ◽  
Ambient Conditions ◽  
Dc Electrical Conductivity ◽  
The Stability ◽  
Almost All ◽  
Conductivity Retention

The films of polyaniline:polyethyleneterephthalate films were prepared by polymerizing aniline soaked in polyethyleneterephthalate films of different thicknesses. The films were characterized by FTIR as well as for their electrical properties. The electrical properties of the films were observed to be of good quality as almost all the films showed a great increase in their electrical conductivity from insulator to semiconductor region after doping with hydrochloric acid. All the films in their doped state follow the Arrhenius equation for the temperature dependence of electrical conductivity from 35 to 115oC. The thermooxidative stability was studied by thermogravimetry and differential thermal analysis. The stability in terms of dc electrical conductivity retention was also studied under ambient conditions by two slightly different techniques viz. isothermal and cyclic techniques. The dc electrical conductivity of the films was found to be stable below 90oC for all the films under ambient conditions.

Effect of chemical admixtures on the sulfate requirement of cement

1980 ◽  
Vol 7 (2) ◽  
pp. 256-263 ◽  
Author(s):  
M. A. Ward ◽  
S. M. Khalil ◽  
B. W. Langan
Keyword(s):  
Portland Cement ◽  
Initial Temperature ◽  
Precast Concrete ◽  
Steam Curing ◽  
Sulfate Content ◽  
Chemical Admixtures ◽  
Cost Of Energy ◽  
Hot Weather ◽  
The Cost ◽  
Ready Mixed Concrete

As the cost of energy and hence the cost of producing Portland cement increase, the question arises as to whether we are obtaining optimum performance from the admixtures we use. As an example, data are presented indicating that a significant improvement in strength and shrinkage can be achieved by optimizing the sulfate content of the cement for given cement–admixture combinations. It is shown that the optimum SO3 is clearly a function of the initial temperature of the concrete, particularly during the first 24 h after casting, a characteristic of considerable importance in hot weather concreting and steam curing of concrete products. It is recommended that more attention be directed towards optimizing the effectiveness of chemical admixtures in both the ready-mixed concrete and precast concrete industries.

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.

Effect of coal additives on the physical and chemical properties of the Portland cement

2018 ◽  
Vol 39 (2) ◽  
pp. 55-64
Author(s):  
Benarima Zine EL abidine ◽  
Belaadi Salah ◽  
Bentaieb Noureddine ◽  
Zirour Fetiha Ralida ◽  
Touil Djamel
Keyword(s):  
Portland Cement ◽  
Chemical Properties ◽  
Physical And Chemical Properties ◽  
Physical And Chemical ◽  
And Chemical Properties
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