Volume 17, Issue 5 (2017)                   MJCE 2017, 17(5): 217-228 | Back to browse issues page

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Nasiri R, Maghsoudi M. Evaluation of Engineering Properties of Control and Composite Concrete Consisting of Limestone Powder and Pozzolan. MJCE. 2017; 17 (5) :217-228
URL: http://journals.modares.ac.ir/article-16-10145-en.html
Abstract:   (737 Views)
Portland-limestone cement (PLC) is a new, more sustainable version of portland cement that is becoming widely available in North America. Known as Type IL cement in the blended cement specifications of ASTM and AASHTO, it has already been approved by many transportation agencies and its use in structures and pavements is rapidly increasing. PLC implementation has been fueled mostly by interest in sustainability, but some experiences have also shown that it can be used to improve concrete performance and even mix economics. Beneficial performance synergies of PLC with fly ash and slag cement (SCMs) have been well documented. Recent research has also studied optimum PLC properties, the most beneficial types and characteristics of SCMs, and the extent to which SCM replacement rates can be extended. In addition to improved strength development, setting, and durability, this more sustainable PLC concrete has been found to improve finishing properties and the quality of formed or slipped surfaces. The webinar will review research and trial project data and highlight successful applications and project experiences to date, sharing implementation guidelines.
More recently, the composite concretes which is consisting of Portland cement, lime stone powder and different types of pozzolans are used in a few countries. This type of concrete is more beneficial as a certain percentage of lime stone powder and pozzolan is substituted by cement weight in concrete. However, considering Iran, although considerable number of cement factories is available, and the economic cost of composite cement, the practical use of such cement is not yet seriously taking into consideration. When designing a concrete structure using composite cement, some of its characteristics and engineering properties become different from those of normal concrete, NC. These differences in material properties may have important consequences in terms of the structural behavior and design of composite concrete members. The design provisions contained in the building codes are, in reality, based on tests conducted on NC. The design of these structural members is not covered in existing codes of practice.
Therefore for the aim of practical usage of composite cements, it is necessary to investigate seriously the plastic phase, engineering properties and durability considerations of this type of composite cement. In this paper, the chemical analysis of composite materials including cement, lime stone powder and Rafsenjan’s pozzolan are performed and the results and analysis of ten designed concrete mixes which are constructed and tested are discussed. The mixes are including control and nine composite (ie. cement type II of Kerman cement factory, Rafsenjan’s pozzolan and limestone powder) concrete. In plastic phase; the tests on slump, setting time and volume expansion of control and composite cement and in hardened phase; the tests on compressive strength for two wet (w) and %5 sulphate sodium (s) curing conditions, different type of tensile strength (i.e. splitting, European and flexural tensile strength) at short and long time ages and water capillary absorptions are carried out. Also, for concepts of practical use of such concretes in reinforced concrete structures, the compressive and tensile stress-strain diagrams are plotted by attaching sensors on two types of concrete. It was concluded that: i) the setting time of composite specimens were lower than that of control concrete specimen, ii) replacing of lime stone powder and pozzolan by cement weight caused to reduce the compressive strength of composite to that of control concrete at early and long ages however, ultimate compressive strain (εcu) of almost all the specimens reached 0.003 which is recommended by ACI standard. and iii) no considerable effect on the compressive strength of specimens was observed for two curing regimes of sulphate (s) and wet (w).
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Article Type: Original Manuscript | Subject: omran
Received: 2016/09/29 | Accepted: 2017/03/13 | Published: 2017/12/22

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