Mechanical properties and durability of ultra-high-performance concrete with calcined diatomaceous earth as cement replacement

Calcined diatomaceous earth (CDE) with a maximum grain size of 143 mu m was used to partially replace 5 and 10% of cement in ultra-high-performance concrete (UHPC) mixtures. The other materials used in producing the concrete include Ordinary Portland Cement, iron ore powder, and river sand with maximum grain sizes 112.5, 231, and 766.2 mu m, respectively. Moreover, the UHPC specimens designed with a water-cement ratio of 0.2 and a superplasticizer of 1.5% from the cement weight were tested for flow, compressive strength, flexural strength, splitting tensile strength, durability against NaCl and Na2SO4 attack, and resistance to 400, 500, and 600 degrees C temperatures. The results showed that the use of 5 and 10% CDE to replace cement was able to increase the compressive strength, flexural strength, splitting tensile strength, the durability of UHPC against NaCl, and Na2SO4, as well as its resistance to high temperatures but reduced the mixture flow.