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Pendant cements form on the bottom of grains where water droplets are held. Hardgrounds are hard crusts of carbonate material that form on the bottom of the ocean floor, below the lowest tide level. Isopachous (which means equal thickness) cement forms in subaqueous conditions where the grains are completely surrounded by water (Boggs, 2006).
Carbonatation is a slow process that occurs in concrete where lime (CaO, or Ca(OH) 2 ) in the cement reacts with carbon dioxide (CO 2) from the air and forms calcium carbonate. The water in the pores of Portland cement concrete is normally alkaline with a pH in the range of 12.5 to 13.5.
AFm form inter alia when tricalcium aluminate 3CaO·Al 2 O 3, or C 3 A in CCN, reacts with dissolved calcium sulfate (CaSO 4), or calcium carbonate (CaCO 3). As the sulfate form is the dominant one in AFm phases in the hardened cement paste (HCP) in concrete, AFm is often simply referred to as Aluminate Ferrite monosulfate or calcium aluminate ...
Hydrotalcite – Hydrated Mg-Al layered double hydroxide (LDH) containing carbonate anions; Tacharanite – Calcium aluminium silicate hydrate mineral (Ca 12 Al 2 Si 18 O 33 (OH) 36, and also Ca 12 Al 2 Si 18 O 51 (OH) 2 · 18 H 2 O) Mechanisms of formation of C-S-H phases: Alkali–silica reaction – Chemical reaction damaging concrete
Calcareous sinter is a freshwater calcium carbonate deposit, also known as calc-sinter. Deposits are characterised by low porosity and well-developed lamination, often forming crusts or sedimentary rock layers. Calcareous sinter should not be confused with siliceous sinter, which the term sinter more frequently [citation needed] refers to.
ASR can lead to serious cracking in concrete, resulting in critical structural problems that can even force the demolition of a particular structure. [4] [5] [6] The expansion of concrete through reaction between cement and aggregates was first studied by Thomas E. Stanton in California during the 1930s with his founding publication in 1940. [7]
Calcium silicate, also known as slag, is produced when molten iron is made from iron ore, silicon dioxide and calcium carbonate in a blast furnace. When this material is processed into a highly refined, re-purposed calcium silicate aggregate, it is used in the remediation of acid mine drainage (AMD) on active and passive mine sites. [ 13 ]
Silicate carbonate minerals can be formed in limestone metamorphosed by heating from igneous intrusions. [1] Scawtite forms where the activity of calcium is high compared to H +. Spurrite forms in a limited range of calcium activity and high silica activity. [2] In magma, a carbonate rich melt is imiscible with a silicate melt. [3]