Note 1 This specifiion is regarded as adequate to ensure satisfactory materials for most concrete It is recognized that for certain work or in certain regions it may be either more or less restrictive than needed For example where aesthetics are important more restrictive limits may be considered regarding impurities that would stain the concrete sur Note 1 This specifiion is regarded as adequate to ensure satisfactory materials for most concrete It is recognized that for certain work or in certain regions it may be either more or less restrictive than needed For example where aesthetics are important more restrictive limits may be considered regarding impurities that would stain the concrete surface