Oolitic limestone is one type of limestone which formed during the Jurassic period and can be found in large deposits in many areas of England. It can be used as coarse aggregate for concrete construction, however due to its porosity, it requires additional cement to maintain compressive strength, when compared to marine gravel (sandstone) concrete. Since freeze/thaw durability is one of the most common problems in temperate countries, this paper investigates the freeze/thaw resistance of Oolitic limestone itself and when used as a coarse aggregate in concrete. The washed oolitic limestone was freeze/thaw tested to BS EN 1367 -1 :2007 and conclusions were drawn. Sixteen concrete cubes (100 mm3) were made, 8 using Oolitic limestone as a coarse aggregate and another 8 using marine gravel. Two cubes (1 Oolitic limestone, 1 marine gravel aggregate concrete) were used in a compressive strength test after 3 days of curing, to establish the strength at which the concrete was subjected to freeze/thaw action and the remaining 14 cubes were subject to freeze/thaw cycles, to a maximum of 56 cycles as informed by BS CEN/TR 15177:2006. Compressive strength, percentage mass lost and pulse velocity were compared and the results showed an equal ability to resist freeze/thaw damage when comparing the marine aggregate and oolitic limestone. Normally, the main role of coarse aggregate in concrete is just to act as a filler which determines strength. However in the case of Oolitic limestone, which is composed mainly of calcite (calcium carbonate), further studies should be made both to determine the mineralogy and its behaviour chemically when exposed to cement paste.
|Built and Natural Environment Research Papers
|Published - Dec 2011