Aggregate is one of the main materials of concrete, accounting for about 70% of the volume of concrete. It is the main material of concrete engineering, and its amount is very large. As a main material, its quality will naturally affect the performance of concrete. The country and the industry have made specific provisions on the quality of aggregates. Even the technicians of concrete manufacturers will set a standard in their hearts according to their own understanding of aggregates. These behaviors will naturally affect the selection and use of aggregates, and even affect the mix design ideas, and ultimately affect the performance of concrete. How to treat and use aggregates correctly is a problem worthy of our deep consideration. Knowing aggregates and rocks can better make concrete.
The precursors of coarse and fine aggregates are rocks, which are naturally produced mineral or glass aggregates with stable appearance and are combined in a certain way. It is the material basis of the crust and upper mantle. It can be divided into magmatic rock, sedimentary rock and metamorphic rock according to its origin. Among them, magmatic rock is a rock formed by the condensation of high-temperature molten magma on the surface or underground, also known as igneous rock. Magmatic rocks that erupt from the surface are called extrusive rocks or volcanic rocks, and those that condense underground are called intrusive rocks. Sedimentary rocks are rocks formed under surface conditions by the transportation, sedimentation and diagenetic consolidation of weathering, biological and volcanic products by external forces such as water, air and glacier; Metamorphic rock is a kind of rock formed by metamorphism due to the change of geological environment of the magmatic rock, sedimentary rock or metamorphic rock. Due to the differences of formation conditions, mineral composition, structure and other factors of various rocks, the physical and mechanical formation of different rocks may be very different.
Magmatic rock The high-temperature molten silicate material (magma) generated in the deep part of the crust or under the crust rises along the weak zone in the crust, invades the shallow part of the crust or erupts out of the surface to condense into rock, also known as igneous rock. The composition of magma is mainly silicate material, and only a few volcanoes have ever ejected carbonate magma (such as eastern Tanzania, Africa) and iron oxide slurry (such as Laco magnetite magma in Chile, South America). There are a large number of oxygen, silicon and other elements in the silicate slurry. These elements each form a complex anion group of various states with silicon oxygen tetrahedron in different forms. During the change of condensed state of these ion clusters, the activity trend of magma also changes. In addition, the active state of magma is also affected by volatile components in magma. The content of volatile components in magma generally does not exceed 6%, mainly water vapor (about 60% – 90% of the total volatile), followed by CO2, CO, SO2, HCI, H2S,