Manufactured Sand meets the development of the times
In 2013, China's cement output exceeded 24 billion tons, and the ready mixed concrete exceeded 1 billion 100 million m3. Fine aggregate sand as an important component of concrete consumption is also huge. Natural river sand is a kind of short-term non-renewable resources, and its distribution is uneven in China. With the large-scale exploitation of river sand, most areas in China have been faced with sand-free, high-quality river sand shortage of resources. Facing the shortage of river sand resources and the rapid development of infrastructure in China, it is urgent to replace natural river sand with new sand resources.
The technical requirements of modern concrete for sand are getting higher and higher, especially for high-strength grade and high-performance concrete, the requirements of aggregate are very strict, and the natural sand to meet the requirements is becoming less and less. Therefore, it is urgent to find new sand resources for concrete. The development and use of machine-made sand has become an important way to solve the shortage of building sand. One of. Since the State Construction Commission formulated the Technical Regulations for Machined Sand Concrete in 1973, the application of machine-made sand has been widely promoted, from construction industry to highway, railway, hydropower, metallurgical and other systems, from retaining works to bridges, tunnels and hydraulic engineering, from masonry mortar to ordinary concrete, reinforced concrete, and pre-construction. Engineering such as stress concrete, pumping concrete, air tight concrete and shotcrete support.
As a substitute for river sand, machine-made sand has become the development trend of concrete in the future. "Building Sand" (GB/T14684-2011) defines machine-made sand as "rock, tailings or industrial waste particles with a particle size of less than 4.75 mm, made by mechanical crushing and screening after soil removal, but excluding soft, weathered particles, commonly known as artificial sand".
The main advantages of manufactured sand are as follows: 1. The surface of manufactured sand is rough and has a fresh interface, and its bonding performance with cement adhesive is superior, and the strength of concrete prepared with manufactured sand is higher; 2. The gradation of manufactured sand can be manually adjusted, which is one of the essential differences from natural sand; 3. The production of manufactured sand can make a lot of waste stone resources. 4. The proper amount of stone powder in machine-made sand can optimize the gradation of machine-made sand and improve the workability of machine-made sand concrete. Stone powder can also play the role of nucleation, accelerating the hydration process of cement; 5) Machined sand basically does not contain harmful substances such as mica, light matter, organic matter.