| At present, mineral powder has been widely used in cement material. But the amount of its replacement is generally less than 30wt%. It is of great significance for improving mineral utilization, reducing cement consumption and protecting ecological environment by improving the content of mineral powder in the cement base material, investigating properties of high content mineral cement materials, especially long-term mechanical properties and durability.(1) Compared with cement as control sample, when the mineral powder content gradually increased in the range of 10wt%~90wt%, the water consumption of the cement standard was gradually reduced and the largest decline was 14.3%; the setting time gradually extended and the maximum extension was 62.5%; mortar fluidity gradually increased and the maximum increase was 10.4%. When the mineral content was less than 40wt% and 50wt%-70wt%, the 28 d strength of cement mortar respectively to meet the strength requirements of 42.5 and 32.5 Portland cement.(2)Through investigating influence of the amount of mineral admixture on the long-term strength of concrete and long-term strength growth rate results, it can be found that the powder doping can increase the later strength of the concrete and improve the later strength of the growth rate. This effect is the most significant in 40wt% mineral content. At the same time, the mineral powder can improve the flexural strength of concrete, so as to improve the toughness of concrete.(3)There are both advantages and disadvantages on effect of mineral powder. With increasing dosage of slag powder, the drying shrinkage rate of concrete increased, resistance to chloride ion permeability is improved, frost resistance reduced. Therefore the use of mineral to replace cement in the production should concern the dry shrinkage property and frost resistance.To sum up, it can meet the needs of different concrete strength by constantly adjusting the dosage of mineral admixture in cement. |
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