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Coarse aggregate, as the component with the highest content in concrete, plays a rigid skeleton role within the concrete. Usually, when concrete is subjected to compressive loads, force is mainly transmitted between internal coarse aggregates. When failure occurs, it mainly manifests as micro cracks appearing at the bonding surface between mortar and coarse aggregates, and then the cracks gradually increase with the increase of load. Finally, the concrete is damaged. It can be seen that using high-quality coarse aggregates is of great significance to improve the performance of concrete.
1. The influence of coarse aggregate strength on concrete performance:
The influence of coarse aggregate strength on the compressive strength of concrete gradually increases with the decrease of water cement ratio. For high-strength concrete, due to the small water cement ratio, there are relatively few micro cracks in the interface transition zone between cement mortar and aggregate. The load is mainly transmitted between coarse aggregates, and although the micro cracks inside the concrete can develop along the interface transition zone, they cannot be interconnected. Therefore, the influence of aggregate strength on ordinary concrete is relatively small, while for high-strength concrete, its strength gradually increases with the increase of coarse aggregate strength.
2. The influence of coarse aggregate water absorption rate on concrete performance:
The water absorption rate of different types of coarse aggregates will also vary to a certain extent, and the water absorption rate of aggregates has a significant impact on the flowability of fresh concrete and the mechanical properties after hardening. When the water cement ratio remains constant, the increase in water absorption of coarse aggregate is equivalent to reducing the water cement ratio around the aggregate, increasing the bonding performance between the aggregate and mortar, and improving the strength grade of concrete; On the other hand, since the water absorbed by the aggregates does not diffuse to the surface of the concrete, this water can serve as a curing agent for the interior of the concrete in the later stage, thereby improving its strength.
3. The influence of coarse aggregate particle shape on concrete performance:
The particle shape of coarse aggregate, as an important physical property of aggregate, also has a prominent impact on the performance of concrete. The slump of fresh concrete decreases with the increase of needle like content in the crushed stone, which in turn leads to a decrease in the workability of the concrete. Therefore, in actual construction, in order to enhance the fluidity of the concrete, it is necessary to control the content of needle like crushed stone as much as possible.
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