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Showing 7 results for Portland Cement

Mahmoud Reza Abdi,
Volume 9, Issue 2 (6-2011)
Abstract

The use of various slags as by-products of steel industry is well established in civil engineering applications. However, the use

of BOS slag in the area of soil stabilization has not been fully researched and developed despite having similar chemical

composition and mineralogy to that of Portland cement. This paper reports on efforts to extend the use of BOS slag to soil

stabilization by determining possible beneficial effects it may have on compressive strength and durability. Results of laboratory

tests conducted on kaolinite samples stabilized with lime and treated with various percentages of BOS slag are presented. Tests

determined strength development of compacted cylinders, moist cured in a humid environment at 35° C and durability by freezing

and thawing method. Results showed that additions of BOS slag to kaolinite samples singularly or in combination with lime

increased unconfined compressive strength and durability. These characteristics were significantly enhanced by the concurrent

use of lime and BOS slag for stabilization of kaolinite.


M. Khorami, J. Sobhani,
Volume 11, Issue 4 (12-2013)
Abstract

Worldwide, asbestos fibers utilized in fiber cement boards, have been recognized as harmful materials regarding the public health and environmental pollutions. These concerns motivate the researchers to find the appropriate alternatives to substitute the asbestos material towards the sustainability policies. In this paper, the applicability of asbestos replacement with three types of agricultural waste fibers, including bagasse, wheat and eucalyptus fibers were experimentally investigated. To this end, the flexural behaviour and microstructure of cement composite boards made by addition of 2 % and 4 % of waste agricultural fibers in combination with and without 5 % replacement of silica fume by mass of cement were evaluated. The results of this study attested the applicability of utilized waste agricultural fibers in production of cement composite boards by improving the flexural and energy absorption characteristics, more or less, depending on the type of fibers. Moreover, it is found that application of silica fume in production of cement composite boards led to an increase in flexural strength.
A. H. Eghbali, K. Fakharian,
Volume 12, Issue 1 (1-2014)
Abstract

Portland cement can be mixed with sand to improve its mechanical characteristics. Many studies are reported in literature on this topic, but the effect of principal stress rotation has not been investigated yet. Considering the inherent anisotropy of most sands, it is not clear whether the added cement shall contribute to equal increase in strength and stiffness at vertical and horizontal directions or not. Furthermore, it is not well understood how the cement as an additive in non-compacted (loose) sand compared to compacted (dense) sand without cement, contribute to improving the material behavior in undrained condition such as limiting the deformations and the liquefaction potential. In this research, undrained triaxial and simple shear tests under different stress paths are carried out on different mixtures of Portland cement (by adding 1.5, 3 and 5 percent) with clean sand to investigate the effect of principal stress rotations. The triaxial test results revealed that the cement mixture reduces the anisotropy, while it improves the mixture mechanical properties compared to compacted sand without cement. The results of the simple shear tests validated the triaxial test results and further clarified the effect of the  parameter or rotation of principal stresses on the behavior of cemented sand mixtures.
A. Allahverdi, M. Mahinroosta,
Volume 12, Issue 4 (12-2014)
Abstract

It was found out that the logarithmic models fit the cement–slag blend systems well. In the present study, based on the experimental results, a logarithmic model has been developed to predict the compressive strength of chemically activated high phosphorous slag content cement. Mixes of phosphorous slag (80 wt.%), Portland cement (14 wt.%) and compound chemical activator (6 wt.%) were prepared at different Blaine finenesses using a laboratory ball mill. Compressive strengths of mortar specimens cured in lime-saturated water were measured at different curing times. Mathematical model was prepared in terms of curing time and water-to-cement ratio as independent variables and compressive strength as dependent variable. The comparisons between the model reproductions and the experimentally obtained results confirm the applicability of the presented model.
A.r. Hariharan, A.s. Santhi , G. Mohan Ganesh ,
Volume 13, Issue 3 (9-2015)
Abstract

This research paper presents the use of wasteful supplementary cementitious materials like fly ash and silica fume to conserve the cement used in concrete. The cement industry is one of the major producers of greenhouse gases and an energy user. In this study, Portland cement was used as a basic cementitious material. Fly ash and silica fume were used as the cement replacements by weight. The replacement levels of fly ash were 30%, 40% and 50%, and silica fume were 6% and 10%. The water binder ratio was kept constant as 0.4 and super plasticizer was added based on the required workability. Results of the binary and ternary concrete mixtures compressive strength, split tensile strength and flexural tensile strength were taken for studyup to 90 days. Based on the experimental results of compressive strength, prediction models were developed using regression analysis and coefficients were proposed to find the split tensile strength and flexural strength of binary-ternary concrete mixtures at 28 and 90 days.
A. Allahvedi, H. Hashemi,
Volume 13, Issue 4 (12-2015)
Abstract

This paper presents an investigation on durability of alkali-activated slag mortar against magnesium sulfate attack. To do so, the immersion tests in 5% magnesium sulfate solution under room temperature and wetting-drying cycles were applied. Mortar specimens from Portland cements type 2 and 5 in accordance to ASTM standard were also prepared and used as reference. The changes in compressive strength and length of specimens were measured at different time intervals and considered for evaluating the extent of degradation. After 360 days of exposure to the magnesium sulfate solution, type 2 and 5 Portland cements and alkali-activated slag cement have shown 61, 41 and 34% reduction in compressive strength and 0.093, 0.057 and 0.021% increase in length, respectively. The specimens were also studied by X-ray diffractometry and scanning electron microscopy for characterizing the chemical products of the degradation process. Main degradation products were ettringite and gypsum for Portland cements and gypsum for alkali-activated slag cement. According to the obtained results, alkali-activated slag cement exhibits a higher sulfate resistance compared to type 2 and even type 5 Portland cements


Ali Allahverdi, Mostafa Mahinroosta, Shima Pilehvar,
Volume 15, Issue 5 (7-2017)
Abstract

Compressive strength is as one of the most important properties of concrete and mortar that its measurement may be necessary at both early and later ages. Prediction of compressive strength by a proper model is a fast and cost-effective way for evaluating cement quality under various curing conditions. In this paper, a logarithmic model based on the results of an experimental work conducted to investigate the effects of curing time and temperature on the compressive strength development of chemically activated high phosphorous slag content cement has been presented. This model is in terms of curing time and temperature as independent variables and compressive strength as dependent variable. For this purpose, mortar specimens were prepared from 80 wt.% phosphorous slag, 14 wt.% Portland cement, and 6 wt.% compound chemical activator at Blaine fineness of 303 m2/kg. The specimens were cured in lime-saturated water under temperatures of 25, 45, 65, 85 and 100 ºC in oven. The model has two adjustable parameters for various curing times and temperatures. Modeling has been done by applying dimensionless insight. The proposed model can efficiently predict the compressive strength of this type of high phosphorous slag cement with an average relative error of less than 4%.



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