Abstract:
This research examined the available data on chemical and physical properties of hydrated lime from limestone and marble deposits in twenty two locations and one hundred and five samples in Nigeria and four locations and sixteen samples from other countries, with the aim of revealing their suitability for cement production. The geochemical data show that the most important minerals in the production of cement or lime from Nigerian and imported limestones are: CaO which varies from 51.4% in the ASTM specification to 51.3% for the imported limestones and 54.1% for the Nigerian limestones; and loss on ignition varies from 32.0% for the Nigerian limestones, 42.0% for the ASTM specification and 42.3% for the imported materials. Also of significance is the amount of SiO2 which varies from 4.0% in the ASTM specification, 4.0% in the Nigerian limestones and 1.5% in the imported limestones. Apart from MgO, the other minor minerals have compositions generally above the ASTM specification. Results from the geotechnical data show the average for the Nigerian limestone deposits for apparent porosity 0.61, hardness 2.86, bulk density 2.61g/cm3, specific gravity 2.71, compressive strength 91.3MPa, tensile strength 3.84MPa, pH 8.36, and shear strength 10.49MPa. Most of the physical properties of Nigerian limestones fall within the range of ASTM specification, except the shear strength and apparent porosity which fall below the recommended range. The apparent porosity of Nigerian limestones is 0.61 while that of imported limestones is 0.62. The compressive strength of the Nigerian limestones is 91.3MPa while that of the imported limestones is 89.6MPa. Also the bulk density for the Nigerian limestones is 2.61g/cm3 while it is 2.60g/cm3 for the imported limestones.
An overall chemical and physical properties evaluation indicated that most of the limestone deposits in Nigeria are suitable for cement production. Statistical analysis of all the samples tested showed that CaO, MgO, K2O, Na2O, Fe2O3, SiO2, Al2O3, are all within 95% confidence level for the production of cement. All the samples investigated have very high reliability for manufacturing of cement. In general, there is no major difference between the physical properties of the Nigerian limestones and the imported limestones.
