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Superplasticized vs. Conventional Concrete: A Comparative Review

Materials Sciences and Applications 2024年第9期15卷 271-284页

作者： mark bediako Advanced Material Science Division CSIR-Building and Road Research Institute Kumasi Ghana

The global awareness and utilization of superplasticizers (SPs) in concrete have significantly contributed to developing resilient and sustainable infrastructure. Despite this, many developing nations face limited adoption of SPs in construction practices due to a lack of knowledge. This study provides a concise overview of concrete’s mechanical and durability properties, comparing formulations with and without superplasticizers. The focus is on compressive and flexural strengths, modulus of elasticity, water sorptivity, and chloride penetration. The results underscore the considerable improvement in both mechanical and durability properties when SPs are incorporated. The study recommends the widespread use of SPs, particularly in developing countries, to enhance the longevity of concrete structures.

关键词： Superplasticizers Concrete Mechanical Properties Durability Developing Countries

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Alternative Binders for Increased Sustainable Construction in Ghana—A Guide for Building Professionals

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Materials Sciences and Applications 2013年第12期4卷 20-28页

作者： mark bediako Augustine Osei Frimpong Council for Scientific and Industrial Research—Building and Road Research Institute Materials Division Kumasi Ghana

Sustainable concepts and practices have taken a centre-stage in different fields of studies and professions. This is because human activities continue to threaten the carrying capacity of earth resources as well as life basic needs such as shelter. Ghana, a developing nation, has been characterized with a boom in construction activities. In almost every constructional work, Portland cement remains the main binding agent that is used to bind aggregates together in a monolithic unit. The overdependence of the Ghanaian construction industry on Portland cement has contributed to huge sums of foreign exchange used to import cement ingredients, high cost of buildings and annual artificial shortages of cement which leads to high cost of the product. In this work, alternative binding agent—pozzolana cement, is reported with regards to the theory behind its utilization, laboratory results and practical applications. Results obtained from both the laboratory and the field works have shown that the future binder for the Ghanaian construction industry is pozzolana cement. CSIR-Building and Road Research Institute recommends it for the construction industry for use in various forms of construction such as block making, concrete and mortar works.

关键词： Sustainable Carrying Capacity Alternative Binder Foreign Exchange Pozzolana Cement

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Effect of Curing Environment on the Strength Properties of Cement and Cement Extenders

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Materials Sciences and Applications 2015年第1期6卷 33-39页

作者： mark bediako J. T. Kevern Eric Opoku Amankwah Council for Scientific and Industrial Research Building and Road Research Institute Materials Engineering Development Division Kumasi Ghana Department of Civil and Mechanical Engineering University of Missouri Kansas City Missouri USA Development Office University of Education-Winneba Kumasi Campus Kumasi Ghana

Curing of cement based products such as concrete and mortar, is very important to achieve good strength and durable products. However the curing environment plays a pivotal role in the overall quality of cement based products in terms of strength development. ASTM C192 allows moist curing either in a fog room or under water. However, these must meet ASTM C511 which controls temperature, and specifically for water curing, the concentration of calcium ions in the curing solution. Unfortunately in many parts of the world, water curing literally means curing in tap water. This is done primarily because there is a lack of knowledge or ignorance regarding the mobility and roll of calcium hydroxide in the curing process. To illustrate the differences, in this study, straight ASTM Type I/II Portland cement and that mixed with powdered waste clay bricks as a cement extender were used to prepare two different batches of mortars. The chemical properties of the powdered waste clay brick met the ASTM C618 standard specifications for Class N pozzolans. Both mortar specimens were cured under two different environment comprising of either water and lime saturated water. Mortar specimens were tested for compressive strength at 3, 7, 14 and 28 days of either curing conditions. Test results indicated that mortar specimens cured in lime saturated water obtained higher strength than those cured in fresh water at all ages of curing. Statistical inference drawn from ANOVA testing showed that curing conditions had significant impact on strength development of the blended and unblended cement systems. The study recommends that testing of concrete and mortar samples and other research related works be performed in lime saturated water other than fresh water.

关键词： Curing Water Lime Saturated Water Mortar Compressive Strength ANOVA

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Potential Use of Crushed Ghanaian Limestone in Paste and Mortar Formulated for Masonry

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Journal of Civil Engineering and Architecture 2011年第3期5卷 258-264页

作者： mark bediako Albert A. Adjaottor Simon K. Y. Gawu Council for Scientific and Industrial Research-Building and Road Research Institute KNUST- Kumasi Ghana

Crushed Ghanaian limestone （L） powder was analysed for its physical, chemical and microstructural properties for the formulation of mortar for masonry. Ordinary Portland Cement （OPC） was replaced by 10- 40% limestone powder for paste and mortar formulation. Mechanical properties that included compressive strength, water demand and setting times （initial and final） were determined and analysed. The mechanical properties were determined in accordance with ASTM standards. The test results indicated that crushed limestone powder contained about 88.7% CaO in calcite form. A 10-30% and 35-40% limestone content in conjunction with OPC was suitable to produce ASTM type M and S mortars respectively. Formulated OPC - L paste showed a high water demand, a delayed initial setting time and an accelerated final setting time than the plain OPC paste.

关键词： Limestone powder masonry mortar water demand setting times compressive strength

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