In order to study the engineering application performance of machine-made sand C35 pile foundation concrete with fly ash and slag powder, this paper starts from the workability of fresh concrete, the early strength of concrete, and the early anti-cracking performance, and the mechanism suitable for engineering is obtained The proportion of sand C35 pile foundation concrete, and the economic analysis of the proportion. The research results show that: (1) The mixing of fly ash and mineral powder is beneficial to improve the workability of fresh concrete, but the amount of both should not be excessive. When the amount of fly ash is large, the concrete is easy to bleed and scratch the bottom; when the amount of slag is too much, the concrete is sticky. The water consumption and water reducing agent content increase. When the mixing ratio of the two is 1:2.50 or 1:1.30, the machine-made sand concrete meets the workability requirements of pile foundation concrete. (2) The double mixing of fly ash and mineral powder is conducive to the early strength growth of concrete. When the total content of 35% is kept unchanged, when the mixing ratio of fly ash and mineral powder is 1:2.50, the strength development is optimal, and the machinemade sand at 28 d age, the concrete can reach 121% of the trial mix strength of C35 concrete. (3) The double addition of fly ash and mineral powder is beneficial to the early anti-cracking performance of concrete, and the anti-cracking grade of machine-made sand concrete can reach the requirement of grade IV. (4) The economic analysis of the machine-made sand pile concrete with a mixing ratio of fly ash and mineral powder of 1:2.50 shows that the direct cost of 1 m3 concrete is reduced by 13.2% compared with river sand concrete.
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