DefinePK

Abstract

The concrete is considered as one of the most important building materials. Ordinary Portland cement is used as binding material in concrete production. The manufacturing process of cement is accompanied with carbon dioxide emission. The use of green concrete as environmentally friendly material is very important. The local natural pozzolan (LNP) found in volcanic areas in Almadinah Almunawara in Saudi Arabia can be used as partial replacement of cement and sand to produce light weight concrete with special properties and to improve the mechanical properties of environmental friendly concrete. The main objective of this study is to investigate the effect of partial replacement of cement by weight with local natural pozzolan powder in cement mortar cubes to reduce carbon gas emissions and energy in the manufacturing process of cement. The study also includes the effect of partial substitution for sand used in cement mortar with (LNP) and with partial substitution for cement with silica fume on its mechanical properties. The use of pozzolan with special type of cement is recommended by the Saudi Building Code in case of concrete exposed to sulfate and / or chloride with severe exposure. The experimental work is divided into two parts: cement replacement with (LNP) powder and sand replacement with (LNP) in the presence of silica fume. A 84 cement mortar cubes of 50x50x50 mm were made (6 cubes as control specimens, 24 cubes with cement replacement by weight with (LNP) powder at percentages of 10%, 20%, 30% and 40%, 24 cubes with sand replacement by volume with (LNP) at percentages of 10%, 20%, 30% and 40%, without silica fume, 15 cubes with sand replacement by volume with (LNP) at levels of 0%, 10%, 20%, 30% and 40% and with 5% substitution for cement by weight with silica fume, and 15 cubes with sand replacement by volume with (LNP) at replacement levels of 0%, 10%, 20%, 30% and 40% and with 10% replacement of cement by weight with silica fume). The specimens were tested at 28 and 180 days. The utilization of (LNP) and silica fume showed a marked influence on the mechanical properties of cement mortar specially in the case of sand replacement with (LNP).