**2.1 Sources of aggregate in Ethiopian past, present, and future trends**

The natural aggregates are formed as a result of the processes of weathering and abrasion or through crushing a large parent mass [7]. Engineers are first of all concerned with technical requirements. However, in the future, probably the environmentalists will take over much of the standardization work. Quarrying and transport of materials have environmental impacts on the local neighborhood and society, for instance, with regard to noise, dust, pollution, and effects on biodiversity [8]. The city of Addis Ababa is growing from time to time very rapidly. Its area which is 54,000 Ha is being covered by buildings, houses, roads, bridges, etc. [9]. To meet the overgrowing demand, the number and production capacity of quarry sites, coarse aggregate, and sand deposits are aggressively increasing. Admasu [7] (2015) reported that based on the data from Addis Ababa Environmental Protection Authority in 2005 to 2015, the number of aggregate production plants in the capital has increased from 152 to 257.
