粉煤灰微珠文獻(xiàn)翻譯已修改5the performance study on c60pacting concrete mixed with ultra pozz in different degrees of fineness

1、The Performance of C60 Self-compacting Concrete Mixed With Ultra pozz in Different FinenessAbstract: The workability and mechanical properties of C60 self-compacting concrete mixed with Ultra pozz in different fineness have been studied in this paper. The result shows that when the D50=2.87m Ultra p

2、ozz equivalent replace D50=12.84m grade fly ash, the workability and mechanical properties of C60 self-compacting concrete improved, the autogenous shrinkage reduced.Key words: self-compacting concrete; grade fly ash; Ultra pozzIntroductionThe utilization of Ultra pozz in high-performance concrete (

3、HPC) has become popular recently, but further study on the dosage and fineness of Ultra pozz for large-scale applications in construction should be developed,to find out the reasonable parameters to make high-performance concrete with excellent mechanical properties and volume stability.In this pape

4、r, C60 self-compacting concrete mixed with Ultra pozz and superplasticizer, research the effect of different fineness of Ultra pozz on the workability, mechanical properties and volume stability of concrete.1 Raw materials and test methods1.1 Raw Materials1.1.1 Cement and Mineral admixtures P.O42.5

5、cement, S95 GGBS, Grade I Fly ash, Ultra pozz. The physical properties of cement and mineral admixtures are shown in Table1.Table1 The physical properties of cement and mineral admixturesRaw materialsDensity(g/cm3)Specific surface area(m2/kg)Water requirement (%)Fluidity (%)R28 (MPa)28d Compressive

6、strength (%)P.O42.5 cement3.00360100-51.5100.0Grade I Fly ash2.203409510048.594.2Ultra pozz2.517509010551.5100.0S95 GGBS2.8045510510051.099.0The Fly ash particle size distribution are shown in Figure 1(a/b). As shown in Fig1 (a), Grade I Fly ash particle size distribution is mainly in 050m, D25=5.19

7、m, D50=12.84m, D75=27.15m, D90=48.52m. However, as shown in Fig1 (b), Ultra pozz particle size distribution is mainly in 010m, D10=0.82m, D25=1.72m, D50=2.87m,D75=5.1m, D90=9.7m.(a) Grade I Fly ash (b) Ultra pozzFig1 Fly ash particle size distribution1.1.2 Aggregate Fine sand and gravel performance

8、parameters as shown in Table2 and Table3.Table2 Fine sand parametersFineness modulusMud content(%)Clay content(%)Apparent density(kg/m3)Bulk density(kg/m3)2.201.826301520Table3 Gravel parametersParticle size(mm)Mud content (%)Clay content (%)Crushing index(%)Flakiness particle content(%)Apparent den

9、sity(kg/m3)Bulk density(kg/m3)51600.56.06.0264015301.1.3 Superplasticizer Polycarboxylate superplasticizer, solid content 22%, water reduction 25%.1.2 Test method1.2.1 Fresh concrete workability testAccording to “Ordinary concrete mixture performance test methods” (GB/T 500802002) test slump and flu

10、idity, test concrete cohesiveness by simple viscometer method (to test the emptying time in inverted slump bucket). Simultaneously, test the self-compacting performance by U-shape box according to “Self-compacting concrete application of technical regulations”.1.2.2 Compressive strength testConcrete

11、 compressive strength test according to GB/T 500812002 “Ordinary concrete mechanical test criteria”.1.2.3 Autogenous shrinkage testThe autogenous shrinkage of concrete at early cured stage tested by non-contact method of “Concrete Common long-term performance and durability standard test methods”, G

12、B/T 50082-2009. Test equipment used CABR-NES style non-contact measuring instrument.2 The effect on C60 self-compacting concrete mixed with Ultra pozz in different degrees fineness The concrete mixing proportion of C60 Self- Compacting Concrete with Ultra pozz were shown in Table4, the workability a

13、nd mechanical properties test results were shown in Table5. In the test, when Grade I fly ash was equivalent replaced by Ultra pozz, the slump and fluidity of fresh concrete were improved, emptying time and altitude difference of U-shape box were both reduced, at the same time, the compressive stren

14、gth and surplus value of concrete mixed with Ultra pozz were greatly enhanced compareing to the concrete mixed with Grade I fly ash. Table4 C60 Self- Compacting Concrete mixed Ultra pozz design (kg/m3)NO.CementGrade I fly ashUltra pozzS95 GGBSFine sandGravelWaterSuperplasticizer1300135-1057509151401

15、.7%2300160-807509151401.6%3300180-607509151401.5%4300-1351057509151401.7%5300-160807509151401.6%6300-180607509151401.5%As shown in Table5, the workability of C60 self-compacting concrete gradually increased with the Ultra pozz dosage increaseing, however, the compressive strength was slightly reduce

16、d simultaneously.NO.Emptying time(s)Slump (mm)Fluidity (mm)Altitude difference of U-shape box (mm)Compressive strength (MPa)R7R14R28182206204061.370.775.5272406602058.567.974.4362607001055.465.572.346250660067.776.182.655280710065.074.580.564280730064.372.778.1 2 The effect of cement dosage on C60 s

17、elf-compacting concrete mixed with Ultra pozz The concrete mixing proportion of C60 self- compacting concrete mixed Ultra pozz with different cement dosages was shown in Table6, the workability and mechanical properties test results were shown in Table7. The test shows that reduce the cement dosage

18、resultd in similar workability, reduced compressive strength.Table6 C60 self- compacting concrete mixing proportion with Ultra pozz at different cement dosages (kg/m3)NO.CementUltra pozzS95 GGBSFine sandGravelWaterSuperplasticizer7300180607509151401.5%8280180807509151401.4%92501801107509151401.3%102

19、201801407509151401.3%Table7 The workability and mechanical properties of C60 self- compacting concrete with Ultra pozz at different cement dosages NO.Emptying time(s)Slump (mm)Fluidity (mm)Altitude difference of U-shape box (mm)Compressive strength (MPa)R7R14R2874280730064.372.778.184280740062.566.8

20、75.294280740055.462.572.5104280740052.760.169.6At the same time, we can find that even the cement dosage was reduced to 220 kg/m3, the 28d concrete compressive strength was 69.6Mpa, which meet the requirement of C60 Self- Compacting Concrete mechanical properties. Comparing with specimens NO.10 and

21、NO.3, if the workability and mechanical properties are kept the same, the cement dosage can be obviously reduced when Ultra pozz replaced Grade I fly ash. 4 The autogenously shrinkage test of C60 self- compacting concrete The autogenously shrinkage test results of C60 self- compacting concrete were

22、shown in Fig2. The test results was that the NO.10 autogenously shrinkage is 2.0 at 7d, which is obviously low than NO.3. It means than the autogenously shrinkage will be reduced when Ultra pozz replace grade I fly ash.Fig2 C60 Self- Compacting Concrete autogenously shrinkage test Some researches in

23、dicated that the degree of hydration reaction of fly ash is about 10% at 28d, and increased to almost 20% at 90d. Keep dosage and cured stage the same, even the fineness degree of fly ash changed, there would be no obviously change in chemically combined water and pozzolanic activity. Comparing to f

24、ly ash, the pozzolanic activity of GGBS is 30% at 60d, which is greater than fly ash. The autogenously shrinkage is mostly brought about by cement, therefore, when grade I fly ash were replaced by Ultra pozz, GGBS dosage increased and cement dosage reduced simultaneously, the autogenously shrinkage of C60 self- compacting concrete could be reduced obviously.5 ConclusionsBoth workability and mechanical properties of C60 self- compacting concrete can be obviously improved by Ultra po