Issue 60

A. Boukhelkhal et alii, Frattura ed Integrità Strutturale, 60 (2022) 89-101; DOI: 10.3221/IGF-ESIS.60.07

    1 2 . in i i in S R R R (3) Tabs. 8 and 9 present the performance indices for multiple criteria and the suitable MP content for different performance criteria. With regards to the fluidity retention and compressive strength requirements (PI-1), using 5% of MP was found to be more suitable. For constructions that require fluidity retention and production cost gain (PI-2) (or compressive strength and production cost gain (PI-3)), a substitution level of 20% is considered the best. If all of the three characteristics (fluidity retention, compressive strength and production cost gain) are required (PI-4), adding 20% of MP is the appropriate substitution level.

Mix. ID

Multiple performance criterion

0MP

5MP

10MP

15MP

20MP

23.79

22.68 12.11 11.48 56.14

19.02 18.22 14.36 70.55

17.56 25.00 17.56 87.81

PI-1 PI-2 PI-3 PI-4

22.99

0 0 0

5.95 6.09

29.36

Table 8: Performance indices for multiple criteria.

Performance index Required performance criteria

MP (%)

PI-1

Fluidity retention + compressive strength

5-10

Fluidity retention + production cost gain

PI-2

20

Compressive strength + production cost gain

20

PI-3

Fluidity retention + compressive strength + production cost gain

20

PI-4

Table 9: Appropriate MP content for different performance criteria.

C ONCLUSIONS

B

ased on the experimental results and evaluation of SCC with MP using the concept of a performance index, the following conclusions can be drawn :  All SCC mixtures have satisfactory self-compacting properties at fresh state. The use of MP in SCC enhances the filling and passing abilities.  The addition of MP seems to reduce the need for superplasticizer and water to obtain a similar fluidity to the SCC control mixture. This not only reduces the production cost, but also the w/c ratio, which allows to enhance the performance of hardened SCC.  The time to retain the fluidity of SCC can be extended by using MP, this will be very helpful when transporting concrete over long distances.  At a hardened state, the 28-days compressive strength of SCC with MP ranged from 26 to 37 MPa. This means that is possible to used MP in SCC for construction requiring medium strength. An examination of the risk of static segregation shows that all the mixtures tested are homogeneous and have good resistance to the static segregation.  The use of MP as a partial replacement for cement reduced the production cost and CO 2 emissions, which means that MP is an interesting material to produce an eco-friendly SCC.  The characteristics of SCC may be assigned numerical performance Index values. These values may constitute a reliable means for concrete producers in finding the rate of cement replacement by other cementitious materials. According to the performance index results, the inclusion of 20% of MP in SCC mixtures was beneficial for most of the targeted performance criteria.

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