本报告回顾了未经加工或加工的天然火山灰在混凝土中的使用，并概述了天然火山灰的性质及其在水硬性水泥混凝土生产中的使用。早在发明波特兰水泥之前，就已经用掺有石灰的天然火山灰来加固混凝土和砂浆。如今，它们可以用来提高新拌和硬化混凝土的性能，在某些情况下可能具有经济价值。

This report reviews the use of raw or processed natural pozzolans in concrete and provides an overview of the properties of natural pozzolans and their use in the production of hydraulic-cement concrete. Long before the invention of portland cement, natural pozzolans mixed with lime were used to strengthen concrete and mortar. Today, they can be used to enhance the properties of fresh and hardened concrete and may provide economic value in some cases.