Case study of the statistical distribution of the concretes implemented at Qazvin

Subject Areas : Structural Engineering

Ali  Ebrahimi ¹ (Student of MSc, Faculty of civil and surveing, Qazvin Branch, Islamic Azad university, Qazvin, Iran.)
Mahdi  Mahdikhani ² (bAssistance Professor, Faculty of Civil Engineering, Imam Khomeini International University, Qazvin, Iran)

Received: 2017-06-30 Accepted : 2017-08-16 Published : 2017-09-30

Keywords: standard deviation, specified strength, target strength, strength margin, project sensitivity coefficient,

Abstract :

Characteristics of produced concrete become changedthrough changingthe characteristics of materials constituting the concrete. These changes include: The quality of cement, the real ration of water to cement: with neglecting the further water within the aggregates or lack of that, the consideredratio fluctuates and the characteristics of the aggregate which are related to the following dimensions: quality of aggregate, shape of aggregate and aggregate grading. The calculated strength in the mix design is the mean target strength which is marginally further than the specified strength. This further margin lowers the ration of water to cement in calculations and consequently, for a stable flow, the amount of consumption or alloy of cement in concrete increases. On the other hand, the amount of the margin depends on the following factors: The sensitivity level of the concrete project (with K coefficient) and standard deviation of concrete production. The purpose of defining this laboratory project is to obtain an optimal concrete mix design for different consumptions and consequently comparison of theoretical and workshop results in the mix design, lowering the cement consumption and the costs of concrete productions in batching and increasing or stabling the specified strength of concrete through lowering the level of cement consumed in concrete. In this procedure, concrete is produced through common method that is segregating sand from cement to compare that with the results obtained, and to calculate standard deviation fall, strength margin and cement alloy fall in order to produce concrete which is statistically suitable for the required strength.

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