study on the effect of micro-silica and nano-silica combination on the property of high-performance, lightweight concrete

Concrete is among the most commonly utilized construction materials in the world. due to population growth and the urgent need to resettle people, the need for tall buildings has arisen, so engineers have shown a great deal of interest in using high-performance concrete because this type of concrete has valuable mechanical, durability, and workability properties. one of the disadvantages of concrete structures is their very high dead weight, which results in negative detriments such as increased vulnerability to earthquakes, bulky structural components, and consequently high consumption of building materials, which also have destructive environmental effects. using lightweight concrete is an excellent solution to reduce the dead load of concrete structures. still, using lightweight aggregates reduces concrete's main characteristics, such as its mechanical properties. considering the synergistic effect of the simultaneous use of micro-silica and nano-silica with each other in concrete as cement substitutes, this article investigated the possibility of compensating for the weaknesses of lightweight concrete with the mentioned technique. the assessment was performed by doing tests such as compressive strength at the ages of 3, 7, 28, and 91 days and 28-day water absorption and oven-dry density tests with two types of curing, lime-saturated pool and laboratory environment with an average humidity of 80%. also, the slump test of fresh concrete was performed in the workability section. the results indicate that the simultaneous combination of micro-silica and nano-silica can provide characteristics of high-performance concrete, so high-performance, lightweight concrete is possible.