3.2. Building stone, sand and aggregates

Building stone, sand and aggregates are the oldest, widely available and durable building materials. These important and widely used materials, by themselves, could be considered as no-energy materials, however, for the purpose of their processing and transportation, some energy would be required which will make them low-energy materials. The energy used is, principally, for mining, crushing and transporting. In the case of dimension stone, in addition to energy requirements for quarrying and transportation, some energy is required for cutting and polishing stones which are done in stone cutting factories with sophisticated machinery and the use of electrical energy. In the case of sand and aggregates, which are the main ingredients for concrete and mortar making additional energy is used for screening them, thus, making them suitable for the purpose of their use.

In most developing countries and depending on the local circumstances most operations related to the use of stone in building construction are carried out manually. Some values for the energy requirements from different sources are given in table 1 below. These values are exclusive of transporting of materials to the site and do not include the energy of manual work involved.

Table 1. Energy requirements of some stone-based materials