Investigation of the effect of silica sand replacement with sand and quartz powder on compressive strength of reactive powder concrete

Reactive Powder Concrete (RPC) is a ultra-powerful concrete with superior physical and mechanical properties, which was registered in France in 1994. This concrete uses high cement factor, fine powdered materials, low water to cement ratio, and the use of superplasticizer with high compressive strength and very low permeability, high durability and abrasion resistance. the high amount of cement and microsilica used in this concrete not only increases the cost of production, but also increases the heat of hydration. On the other hand, cement production can have harmful effects on the environment. In the production of reactive powder concrete, fine-grained powder materials such as silica sand, microsilica, and quartz powder are used as materials. This concrete has a high compressive strength compared to conventional concrete, which has attracted much attention in recent years. With this type of concrete, the weight of the structure can be significantly reduced, and its important features include high compressive strength, low permeability, durability and abrasion resistance and high ductility that can absorb more energy during an earthquake. Iran has a lot of desert lands and mines, which is one of the first 10 countries in the world and the first in the Middle East in terms of mineral deposits. The bulk of Reactive Powder Concete is formed from the sand. In this research, the purpose of producing reactive powder concrete with the desired mechanical properties of ordinary sand of the Ceram mine of Tabriz, passing through a sieve of 2.36 mm, was used as a substitute for silica sand from the Ghum Tapa mine (which naturally has a grain of less than 600 Micro-meter) is near the city of Tabriz. In this research, after examining the mechanical properties of the used sand, five mixing plans containing 0, 25, 50, 75 and 100% ordinary sand were prepared and Then, by replacing the ordinary sand of the Ceram mine of Tabriz instead of silica sand, The quartz powder used in this design was discarded and the amount of ordinary sand in this mixture was tested using the test method. This design is in fact a special cement sand mortar that has a microsilica and Superplasticizer that lowers production costs, while at the same time has enough resistance to use in practical applications. Prior to molding the molds, a flow table test was conducted to evaluate the concrete's workability and consistency. Concrete samples made at the Concrete Laboratory of the Azarbaijan Shahid Madani University and opened the molds after twenty-four hours and placed the samples in the water at a temperature of 23 to 25 degrees Celsius. Compressive strength, water absorption during curing in 7, 28 and 90 days life has been tested. The results indicate that by increasing the replacement percentage of ordinary sand, instead of silica sand, compressive strength is increasing. In 7-day samples, the highest compressive strength for concrete with 100% ordinary sand is obtained and in 28-day and 90-day samples with 75% and 50% replacement rates have the highest compressive strength, respectively. the compressive strength has increased and also the removal of quartz powder from the mixing design has been accompanied by a decrease in compressive strength, it can be to dismiss this reduction of resistance in order to economize the plan and make it more desirable and The experimental results also show that ordinary sand can be used as a substitute for silica sand and quartz powder In the mixing design of the reactive powder concrete, that make a kind of self-compacting mortar it can be to used The results of the experimental study indicate that ordinary sand can be used as a substitute for silica sand in the production of reactive powder concrete. It should be noted that in each area, with local building materials, these tests should be repeated. The results of this study are related to the silica sand and the above-mentioned ordinary sand.