Development And Research On The High-performance Admixture Of Concrete

In this dissertation, silica fume, fly ash, slag powder and limestone powder were chosen as mineral admixture. Based on the analysis of the shim and pack mineral admixture mechanism and the project of the test, experiment was studied. The net flow of plasma experiments, mortar testing, concrete strength testing and durability testing for the cement clinker were carried through. The results show that mineral admixture have a good performance such as slowdown water when the mineral admixture were made at the condition of the proper content. In the active of the activator on the high content of mineral admixture, the forepart and the anaphase strength of the concrete can be improved significantly when the great use of the mineral admixture .In the net flow of plasma experiments, in the act on the silica fume, fly ash, slag powder and limestone powder, when the content of silica fume 0.5%, fly ash30%, slag powder35% ,net flow of plasma was reached 280mm.Results indicated that the strength of 40% slag powder was equal to the pure silicate cement under the W/B=0.5. The strength of 50% slag powder was slow descended at the age of 3d and 28d. When changed the W/B, under the W/B=0.47, the anaphase strength of the concrete can be improved significantly. It was obviously that the active of theâ… state of fly ash was higher theâ…¡state of fly ash. Holding the content of fly ash 40%, it had the best excited effect and when the activator were tri-ethanol 3‰+sodium sulfate 2%. The strength of 3d and 28d was approach to the pure silicate cement. When the combination of mineral admixture was silica fume0.5%+ fly ash20%+ slag powder30% and the activator was gesso 1.0%, it had a great effect on the strength. The forepart strength of the concrete can be improved significantly when the use of the activator.The anaphase (28d)strength of the concrete can be increased last out. When the strength of the concrete was C40, at the mineral admixture of silica fume0.5%+ fly ash20%+ slag powder30% and the activator was gesso1.0%+ NaOH1 .0%+ Na₂CO₃0.5%, it had a great effect change on the increasing of concrete strength. Particularly in the strength of 7d and 28d, the strength of 28d achieved 50.78 MPa which was higher than the strength of pure silicate cement 46.67 MPa.According to the durability testing for the cement and the micro-scanning electron microscopy and digital photos, results indicated that the durability on the corrupt of sulfate and resisting on carbonization was improved greatly.At the basis of analysis of the mechanism of the mineral admixture and the experiment result, this paper gave the excellent high-performance admixture combination--silica fume0.5%+ fly ash20%+ slag powder30%, and the proper activator --gesso1.0%+ NaOH1.0%+ Na₂CO₃0.5%. Using the super splice of mineral admixture (namely 1+2≥3 ), it can exert the merit of the combination of mineral admixture, and at the same time ,it can also overcome the performance bug of singleness of mineral admixture, also can reduce the cost on concrete .