Effects of Chemicals as Impurities in Mixing Water on Properties of Concrete

Abstract

The hardening of cement gives strength and durability to concrete. The impurities in mixing water may affect the setting, hardening and strength of the concrete. Great control on properties of cement and aggregates is exercised, but the control on the quality of water is neglected. The suitability of a particular source of water for making concrete can be checked by casting concrete cubes using water under question and potable water and comparing its 7 days and 28 days strength. If the compressive strength is up to 90 percent, the source of water may be accepted. The aim of the present study was to know the effect of chemical impurities in mixing water on different properties of concrete. This work was carried out for a mix of concrete with 0.473 w/c ratio using mixing water with various concentration of Calcium Sulphate (CaSO₄), Sodium Hydroxide (NaOH), Calcium Hydroxide (Ca(OH))₂, Ferrous Sulphate (FeSO₄), and Sodium Nitrate (NaNO₃) to study  effect of chemical impurities on the strength development of  concrete at 7, 14, 28  and 56 days. Decrease in strength of concrete was observed with age and concentration of chemical in mixing water.