Indigenous resources for natural and artificial mineral admixtures with high pozzolanic reactivity have been employed in many countries around the world. Extensive studies have been conducted for this purpose. With the use of agricultural waste residue, apart from improving properties of concrete, main benefits come from saving natural resources and energy, as well as protecting the environment by using these mineral admixtures (agroagricultural waste). The effective level of blending Portland cement (PC) in mortar or concrete with such mineral admixtures depends on many factors, such as the type of admixture and the cement replacement level. In the present paper two types of agroagricultural waste residue, namely, rice husk ash, bagasse ash and byproduct from thermal waste and fly ash were used. The above mentioned admixtures were thermally treated at a temperature of 650∘C. Characterizations of mineral admixtures were carried out by FTIR and XRD, and Microstructural properties were evaluated in concrete and mortar with partially replacement levels varying from 5% to 30%. Various tests such as water absorption, bulk volume of the specimen, dry weight of the specimen saturated mass, and coefficient of water absorption were concluded. The results showed that as the percentage of replacement level increases in the entire three admixtures studied, water absorption also increased.