Advanced Materials Research Vol. 824

Abstract: Large volume of reclaimed asphalt pavements (RAP) aggregates are generated during pavement rehabilitation and reconstruction and disposed along road alignment while large quantities of groundnut shell ash (GSA) are generated from the combustion of groundnut shell and also disposed in large quantities on production sites. This paper presents results of the laboratory evaluation of the characteristics of GSA stabilized RAP with a view to determining its suitability for use as highway pavement material in flexible pavements construction. The RAP-GSA mixtures were subjected to British standard light (BSL) (standard Proctor) compactive effort to determine the compaction characteristics and California bearing ratio (CBR). Test results show that the properties of RAP improved with GSA treatment. The particle grading improved from 99.13% coarse aggregate and 0.87% fines, with AASHTO classification of A-1-b for 100% RAP and 9.08% coarse aggregate and 90.92% fines, with AASHTO classification of A-4 for 100% GSA to 15.6691.72% coarse aggregate and 8.2884.32% fines, with AASHTO classification in the range A-4 (silty soil) to A-1-a [granular material, for the various RAP-GSA mixes. Maximum dry density (MDD) decreased while the optimum moisture content (OMC) increased with higher GSA content in the RAP + GSA mixes. Optimum CBR values of 22.2% (unsoaked) and 18.3% (soaked) were recorded for 80% RAP + 20% GSA and 90% RAP + 10% GSA mixes, respectively. This optimum mixes satisfied durability requirement with insignificant water absorption and can be used as subgrade material in flexible pavements. This research provides the results to the evaluation of GSA stabilized RAP as highway construction material, as it is based on CBR determination. Further work may be encouraged to assess resilient modulus of this material under cyclic load.

Abstract: Large quantities of groundnut shell ash (GSA) are generated from the combustion of groundnut shell, disposed in large quantities on production sites while large volume of reclaimed asphalt pavements (RAP) aggregates are also generated during pavement rehabilitation and reconstruction and disposed along road alignments. This paper presents results of the laboratory evaluation of the effect of compactive efforts on the strength properties of GSA stabilized RAP with a view to determining its suitability as highway pavement material in pavement constructions. The RAP-GSA mixtures were subjected to Reduced British Standard light, RBSL (reduced Proctor); British Standard light, BSL (standard Proctor); West African Standard, WAS and British Standard heavy, BSH (modified Proctor) compactive efforts to determine the compaction characteristics, California bearing ratio (CBR), durability and water absorption characteristics. Test results show that the properties of RAP improved with GSA treatment. The particle grading improved from 99.13 % coarse aggregate and 0.87 % fines, with AASHTO classification of A-1-b for 100 % RAP, and 9.08 % coarse aggregate and 90.92 % fines, with AASHTO classification of A-4 for 100 % GSA to 15.6691.72 % coarse aggregate and 8.2884.32 % fines, with AASHTO classification in the range A-4 (silty soil) to A-1-a (granular materials), for the various RAP-GSA mixes. Maximum dry density (MDD) decreased while the optimum moisture content (OMC) increased with higher GSA content in the RAP + GSA mixes and with decreased compactive effort from BSH to RBSL. Optimum CBR values of 35.1% (unsoaked) and 44.1% (soaked) recorded for 90% RAP + 10% GSA mix achieved with BSH compactive effort, satisfied the durability requirements with insignificant expansion and water absorption and can be used as subbase material in flexible pavements construction. This research provides the results of evaluation of the effect of compactive efforts on the strength properties of GSA stabilized RAP as highway construction material, as it is based on CBR determination. Further work may be encouraged to assess resilient modulus of this material under cyclic load.

Abstract: Lateritic soil treated with up to 20% glass cullet content was subjected to grain-size distribution, consistency tests, specific gravity tests, compaction using standard proctor, California Bearing Ratio (CBR), unconfined compression test, direct shear test and permeability tests. The study showed increase in grain sizes resulting in coarser soil, changes in moisture-density relationship, resulting in lower Optimum Moisture Content (OMC) and higher Maximum Dry Density (MDD), an increase in CBR, an increase in unconfined compressive strength (UCS); changes in cohesion-frictional angle relationship resulting in lower cohesion (c) and higher angle of internal friction (Φ) and an increase in co-efficient of permeability, k, with increased glass cullet treatment. These results show an improvement in geotechnical properties, making glass cullet-lateritic soil blend; a potentially good highway material and suggesting the suitability of the blend for embankments, structural and non-structural fill and retaining wall backfill.

Abstract: Laterite was treated with calcium carbide waste and lime as the control, to ascertain its modification and stabilization potential, in incremental order of 2% up to 10 %. Atterbergs limits test, compaction test, California bearing ratio (CBR) and unconfined compressive strength (UCS) test was performed on laterite treated with both additives. The use of χ² test to compare results of tests, showed that there is no significant difference between the modification potential of both additive as reflected in χ² values of 1.293, 0.995 and 0.650 obtained from the comparison of liquid limit, plastic limit and plasticity index test results. However difference was observed with CBR and 7 day UCS test results as χ² values of 13.75 and 11.64 respectively were higher than the standard value of 9.49 obtained from statistical Table at 4 degree of freedom and 5 % level of significance. Based on result of tests, calcium carbide waste is recommended for use in soil modification and stabilization, as usage will provide an effective way of disposing calcium carbide waste.

Abstract: The effect of three different curing conditions on the compressive strength and water absorption of lateritic interlocking bricks, produced with laterite stabilized with 0 %, 2 %, 4 %, 6 % and 8 % cement content was investigated. The study is aimed at providing an alternative to the conventional method of curing interlocking bricks. The three curing conditions used in the study are A (covering of bricks with tarpaulin after sprinkling with water twice a day) B (complete immersion in water) C (complete covering with air and water tight polythene bags). Laterite used in the production of interlocking bricks was as an A-2-7 soil, using the AASHTO system of soil classification. Compressive strength of bricks increased with cement content and days under the different curing conditions, 28 day optimum compressive strength values of 4.28 N/mm², 3.67 N/mm² and 3.67 N/mm² at 8 % cement content was obtained from bricks using curing condition C B and A respectively. Water absorption value decreased with cement content under the different curing conditions, minimum water absorption values of 2.44 %, 1.68 % and 1.72 % at 8 % cement content was obtained with bricks cured under curing condition A B and C respectively. Based on results of test, curing condition C is recommended for use in the production of cement stabilized interlocking bricks, as this will enhance effective production of interlocking bricks in areas where water is scarce.

Abstract: This paper discusses the perception of gravel suppliers in the six states situated in South-western Nigeria. It reported findings from a research on gravel supply studies in the study area. Major gravel pits, together with their perceived technical characteristics in the states were identified through a structured questionnaire designed to solicit response from truck drivers and association of gravel suppliers. Based on this, factors affecting gravel supply and usage were measured by random variables devised for the purpose. The observed outcomes of the variables from the survey carried out constituted the research data. The collated data was analyzed based on quantitative method through the use of simple percentage method of data analysis. The paper posits that geological location of Lagos state is responsible for the absence of any gravel pit in the state, hence the prohibitive cost of gravel in the state when compared to other states in the zone. In all the states, more than 99% of gravel suppliers attribute transport as a major factor affecting the cost of gravels. The technical characteristics of gravels from South-western Nigeria are also perceived to be good in construction, though these assertions need to be empirically proved.

Abstract: Objects and engineering structures are subject to displacements resulting from numerous internal and external factors. Determination of the magnitude of these displacements is possible on the basis of cyclic measurements of changes in position of points determining the geometrical shape of the studied object. Processing the measurement results is aimed at determining the characteristics of the changes and assessment of possible hazards. The paper proposes a methodology for processing repeated GPS data from two-measurement epoch 2010 and 2011 using a model that utilizes multi-parameter transformation, relating original and repeated observations. The mathematical model was applied to original and repeated Global positioning system (GPS) station observations made to target points at Ikpoba Dam in Benin City. The transformation consisted of a parameter similarity transformation at the reference station (translations in the X-, Yand Z-directions at the instrument station, and rotations about the X-, Y-and Z-axes), plus a scale factor relating original and repeated instrument-target. Using MATLAB programme, three control points were transformed and the coordinates of all other monitoring and reference stations were obtained with reference to the transformed control points.Points displacement between the measurement epoch were then computed from the transformed coordinates. The results obtained showed a maximum error of 1mm on the X coordinate, 2mm on the Y coordinate and 7mm in elevation.

Abstract: Oil contaminated soils (PCS) was treated with up to 6% rice husk ash (RHA) by dry weight of soil. Specimens of treated soil compacted at the energy of the standard Proctor (relative compaction = 100%) were subjected to compaction, unconfined compressive strength (UCS) and California bearing ratio (CBR) tests. The results of laboratory tests show that properties of the treated soil improved with RHA treatment. Peak unconfined compressive strength value of 410kN/m2 was obtained at 2% oil/ Applying the conventional evaluation criteria reveals that soil-oil RHA mixture containing 2% oil/4% RHA, 4% oil/4% RHA and 6% oil/4% RHA yields optimum CBR values of 4.6, 4.4 and 3.5% which does not satisfy the minimum required CBR of 15% for use as a subgrade material in road foundation.

Abstract: This paper presents the results of an evaluation of lime treated oil contaminated soil for use in waste containment systems. Soil samples were treated with up 6 % lime contents. Specimens were prepared at optimum moisture content and compacted using British Standard Light (BSL) or Standard Proctor (relative compaction = 100%) to evaluate its effectiveness when used in waste containment applications. The hydraulic conductivity values increased with higher lime contents but were less than 1 x 10^-9 m/s required for a liner material.