Evaluation of selected basement complex rocks from Ado-Ekiti, SW Nigeria, as source of road construction aggregates

Abstract

The petrographical and physical properties of major Precambrian basement rocks in Ado-Ekiti, Nigeria, were evaluated with a view to determine their suitability as road construction aggregates. Fifty rock samples were collected and subjected to petrographic evaluation and laboratory tests (water absorption capacity, specific gravity, Los Angeles abrasion value, aggregate crushing value, aggregate impact value and ten percent fines, flakiness index and unconfined compressive strength). Petrographical analysis revealed that the rocks (migmatite gneiss, quartzite, granite and charnockite) were predominantly acidic, rich in quartzo-feldspathic minerals. Opaque minerals in the rock units ranged between 0.6 and 2.3 % with maximum value in fine-grained charnockite. The specific gravity of the rock aggregates ranged between 2.65 and 2.74. All water absorption capacity values conform to recommended standard value of water absorption capacity \2 %. The aggregate crushing value of the rocks ranged between 17.6 and 28.4 % with minimum from quartzite (17.60-18.40 %) and highest in migmatite gneiss (27.70-28.40 %). The aggregate impact value ranged between 11.0 and 19.0 %, with the lowest value (11.0-11.6 %) from quartzite and highest in charnockite (18.4-19.0 %). Other properties including Los Angeles abrasion, ten percent fines, flakiness index and unconfined compressive strength ranged 17. 4-29.8 %, 96.96-131.63 kN, 13 and 24.9 and 138.98-167.52 MPa, respectively. Based on physical and mechanical properties of the rock aggregates in this study, quartzite, and fine-medium grained granites were considered most suitable for road aggregates production as the tests were within the acceptable limits for general road aggregates purposes. Porphyritic granite, the migmatite gneiss and charnockites showed results for which most values were outside, at the margin or slightly within the acceptable limits for general road stone purpose. The geotechnical assessment provided by this study revealed that not all the Precambrian basement rocks would yield aggregates that are satisfactory for use as road aggregates.

Strength and abrasive properties of andesite: relationships between strength parameters measured on cylindrical test specimens and micro-Deval values—a tool for durability assessment

“…Relationships were also found between the amount of the aluminium, sodium and iron oxides and LA coefficient in the case of sandstones (Tugrul and Yılmaz 2012). Textural properties can affect the physical and mechanical properties as well (Afolagboye et al 2016), as Wang et al (2015) f Andesite 13-Sárospatak. All images were taken with single polar, except image e where crossed polars were used (scale bar 0.5 mm) (compare the textural descriptions given in Table 1)…”

Petrographic and Mechanical Analyses of Selected Granitic Rock Deposits in Ado-Ekiti, South-West Nigeria.

“…Outcrop of quartzites occurrence in Ado Ekiti can rise to 100 m above the surrounding ground level. Their exposure can be linked to continual weathering and erosion due to uneven terrain in the region (Afolagboye, Talabi and Akinola, 2016). The samples points cut across the Ado and Irepodun/Ifedoun Local Government Areas of Ekiti State.…”

“…Table 3 presents the physical properties which include speci c gravity, porosity, and water absorption as well as the uncon ned compressive strength of the granitic rock aggregates under the study. The speci c gravity of a given rock aggregate depends on the density of its minerals and the total void volume present in the bulk materials (Bell, 2007;Afolagboye, Talabi and Akinola, 2016). The speci c gravity of aggregates ranges between 2.63 and 2.71 with a standard variation of 0.03.…”

“…It is essential to estimate the water absorption characteristics of the aggregates since their strength and colour can be attributed to their cement content which depends on the porosity and therefore water absorption (Bell, 2007). Previous works reported that a little increase in the water content may result in a dramatic reduction in strength and deformability (Erguler and Ulusay, 2009;Arif et al, 2013;Afolagboye, Talabi and Akinola, 2016). Eze (E.O., 1997) emphasized that when rock aggregates with water absorption values that exceed 4% are considered for construction application and an additional geotechnical investigation is crucial to ascertain their suitability.…”

Geochemical Trends in Weathering Profiles and Their Underlying Precambrian Basement Rocks in Akure, Southwestern Nigeria

“…The degree of weathering is partly dictated by rock's mineralogy. Rocks with coarse grains are more susceptible to weathering than when the same rock has fine grains [30] .…”