CIVE 2700 Lecture Notes - Lecture 6: Portland Cement, Magnetite, Scoria
4 Apr 2016
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-9 per tonne vs /tonne for cement (aggregates typically 70-80% of concrete) Lower potential shrinkage and creep strains due to long-term loading and drying --> less. Using 100% paste would be highly susceptible to chemical attack. Sand and gravel: gravel pits, river sand deposits, beach sand, rock quarries. Rocks worn-down by natural action (i. e. water) tend to be smooth and rounded. Crushed stone is produced by crushing quarried rocks or large boulders. Open pits take up a lot of space. Produced as an end product of industrial process. Steel slag: waste material from blast furnace. Expanded natural materials: shale, clay or slate. Manufactured sand: crushed stone, gravel, blast furnace slag. Normal weight aggregates for normal density concrete (2150-2500 kg/m3) Low-density structural concrete ( < 1850 kg/m3) Industrial manufactured: slag, expanded shale, slate, clay, hollow glass beads, foamed polymer beads. Suitability of aggregates from given sources depends on physical, chemical and mechanical properties of rocks -- varies within quarry or pit.
