Development of expansive concrete for chemical prestressing applications

Expansive concrete is a specialized type of concrete that expands when mixed with water leading to a larger volume after setting. Such concrete is usually used to compensate for shrinkage. However, although expansive concrete can also be used in self-stressing concrete (chemical prestressing), still such use is very limited. This is because achieving high expansion rates in expansive concrete while upholding desirable mechanical strength and durability characteristics presents a formidable challenge. This study aims to develop expansive concrete capable of achieving substantial expansion rates while maintaining robust mechanical attributes. The research also delves into the material's behaviour over an extended period of time. First, a thorough examination of existing literature was conducted to select the component of the mixture. The mixture was subsequently prepared using various replacement ratios of expansive agent (CSA) in relation to the weight of the cement. These ratios included: 0%, 10%, 12.5%, 15%, 17.5%, and 20%. To study the influence of curing, the specimens were divided into two groups: one immersed in water, while the other was left in dry conditions. The findings have revealed that high expansion values can be achieved when using moderate replacement rations of CSA in combination with continuous water curing. Conversely, low expansion rates were recorded for specimens cured in dry conditions. Notably, such specimens can expand later when exposed to water, which can adversely influence the strength and durability of the concrete.