Journal of Emerging Trends in Engineering and Applied Sciences (JETEAS) 6(1): 49- 56 © Scholarlink Research Institute Journals, 2015 (ISSN: 2141-7016) jeteas.scholarlinkresearch.com Journal of Emerging Trends in Engineering and Applied Sciences (JETEAS) 6(1):49- 56 (ISSN: 2141-7016) Comparative Analysis of Cement and Lime Modification of Ikpayongo Laterite for Effective and Economic Stabilization Manasseh Joel and Joseph Ejelikwu Edeh 1 Department of Civil Engineering, University of Agriculture, Makurdi, 970001, Nigeria. Corresponding Author: Manasseh Joel _________________________________________________________________________________________ Abstract Some geotechnical properties of laterite obtained from Ikpayongo treated with 2 to 10 % cement was compared with the same laterite treated with 2 to 10 % Lime, to determine the most suitable modifier for effective and economic stabilization. Modification potential was assessed using Atterbeg’s limits test, while California bearing ratio (CBR) and unconfined compressive strength (UCS) tests were used to ascertain strength gain with additives concentration. The plasticity index of the natural laterite reduced from 16 % to 7 % and 4 % respectively, when treated with 10 % cement and lime respectively. 7 day UCS value of laterite increased from 534 kN/m2 to maximum values of 1255 kN/m2 and 1090 kN/m2 respectively, when treated with 10% cement and 10 % lime respectively. California bearing ratio (CBR) value increased from 28 % to 135 % and 100 % when treated with 10 % cement and lime respectively. Based on results obtained from the study, treatment of Ikpayongo laterite with 6 % cement or 4 % lime will effectively modify it for economic stabilization. The use of 4 % lime is recommended for modification of Ikpayongo laterite, as the use of excess cement might lead to cracks in the stabilized layer, even though economic analysis is in favour of the use of cement. Results of tests from the study will serve as a guide in the selection of an appropriate modifier for effective stabilization of laterite for roadwork. __________________________________________________________________________________________ Keywords: cement, lime, ikpayongo laterite, modification conditions of combined silica and bases and the relative accumulation or enrichment from outside sources (absolute accumulation) of oxides and hydroxides of sesquioxides (mainly Al2 O3, and Fe2O3, the most resistant components to leaching). The third stage (dehydration or desiccation) involves partial or complete dehydration (Sometimes involving hardening) of the sesquioxide rich materials and secondary minerals. INTRODUCTION The importance of road in the development of any nation can hardly be over emphasized, as it plays a crucial role in the transportation of goods and services. This is normally achieved through the vast network of roads that connect rural and urban centers. Efforts at achieving the construction of more roads is hindered by the high cost of building new roads, attributed to the non availability of suitable road building materials within the vicinity of most road projects. Laterite, a sedimentary rock deposit arising from the weathering of rocks, is one of the most common and readily available road building materials that can be sourced locally in Nigeria. Laterite has been defined by different authors using different criteria, but for simplicity and ease of understanding laterite as defined by Ola (1983) as the products of tropical weathering with red, reddish brown, and dark brown colour, with or without nodules or concreting and generally (but not exclusively) found below hardened ferruginous crust or hard pan, will be adopted in this study. GEOLOGY OF IKPAYONGO LATERITE At Ikpayongo, a distance of 22km from Makurdi, the capital of Benue State of Nigeria, West- Africa, is found a deposit of laterite, divided into two equal parts by the main road linking Makurdi to Otukpa. Ikpayongo laterite is located in the Benue trough (which is more than 800 kilometers in length and varies in width from 100 kilometers in the south to about 150 kilometers in the north. The Benue trough is conventionally divided into three sections; the lower, Middle and the Upper. According to (Rahaman and Malomo, 1983) sedimentation in all the sections started in the cretaceous (Albian) and ended at Upper-most Cretaceous times (Maestrichtian). The lower section where Ikpayongo laterite deposit is situated is dominated by the Abakaliki anticlinorium. Maximum thickness in the lower section estimated by Cratchley and Jones (1965) from gravity a study probably does not exceed 4300 meters. Ford (1989) describe laterite found in Laterite formation process can be categorize into three major stages namely; decomposition, leaching and dehydration/desiccation. The first stage is decomposition which is characterized by physical and chemical break down of primary minerals and the release of constituent elements. The second stage involves the leaching, under appropriate drainage 49 Journal of Emerging Trends in Engineering and Applied Sciences (JETEAS) 6(1):49- 56 (ISSN: 2141-7016) cement, based on findings by (Joel and Agbede, 2011; Eze-Uzomaka and Agbo, 2010) this observation clearly shows that there is need for a modifier or admixture in the stabilization of Ikpayongo laterite with cement. Although cement and lime have been used for modification/stabilization of soil, there is need for a study that will help identify the most effective modifying agent that will upgrade the geotechnical properties of Ikpayongo laterite to a level that economic stabilization with cement can be achieved. The study is restricted to the use of cement and lime, due to their availability and cost. the Benue trough as a residual weathering product on partially or wholly decomposed basalts and other basic to intermediate igneous rocks. Other sedimentary deposits that characterize the trough are limestone, clay and shale. Limestone deposits exist at different locations in the Benue trough, such locations within the lower Benue trough are Gboko, Igumale and Nkalagu, where different cement factories are being situated. The abundance of clay and shale formation is also a noticeable feature of the lower Benue trough. All this could help one understand the origin and formation of laterite at Ikpayongo, this may have been the outcome of the weathering of basalts, which resulted in products like limestone, clay, shale and laterite, all possible products of the weathering of basalts within the trough. An admixture or a modifier according to Punmia (2005) refers to certain chemicals sometimes added to soil-cement, to reduce the cement consumption or make a soil suitable for stabilization, when not responsive to cement alone in its natural state. Lime and calcium chloride are common chemicals normally applied to soils containing clays or organic matter. When the amount of cement added is insufficient to harden the soil enough to meet soilcement stability and durability criteria, cement usage under such condition according to O’Flaherty (1974) is aimed at modification, as the resultant material may fragment under the action of traffic, high waterholding capacities and volume change are characteristics of such soil, which may cause excessive distortion of pavements, due to low supporting values, as their moisture content vary with the weather. The geotechnical characteristics and field performance of lateritic soils, as well as their reaction to different stabilising agents according to Makasa, (2004) may be interpreted in the light of genesis and pedological factors (parent material) degree of weathering, clay-size content, depth of soil in the profile. The behaviour of laterite soils in pavement structure has been found to depend mainly on their particle-size characteristics, the nature and strength of the gravel particles, the degree to which the soils have been compacted, as well as the traffic and environmental conditions. Well-graded laterite gravels according to Thagesen (1996) perform satisfactorily as unbound road foundations. However, where laterite is gap-graded with depleted sandfraction, contain a variable quantity of fines, have coarse particles of variable strength which may break down, their usefulness as pavement materials on roads with heavy traffic will be threatened. In Makurdi, the capital of Benue state, Nigeria Ikpayonog laterite is the main source of borrow material for road construction. It has been used as base and sub-base course material of most of the flexible pavement built within the metropolis. Different types of defects have been observed in almost all the areas where the natural laterite was used as sub-base or base material, this observation is a pointer to the fact that the suitability of the material needs to be assessed. In the past practicing engineers and researchers, have observed that deficiencies associated with laterite can be overcome through different forms of treatment, which in most cases is aimed at modifying or stabilizing the material. The term soil modification as described by Osula (1996) and Sariossieri and Muhunthan (2009) applies to a significant improvement of the soil workability and compaction characteristics and to a minor improvement of the soil mechanical strength using low contents of stabilizers. The addition of a modifier (cement and lime) etc to a soil to change index properties according to Alhassan and Mustapha (2011) is called modification. Modification according to Eluozo and Nwaobakata (2013) refers to soil improvement that occurs in the short term, during or shortly after mixing (within hours). It is aimed at reducing plasticity of the soil to the desired level, short term strength gain, (i.e. strength derived immediately after application to about 7-days of compaction). In summary soil modification may or may not lead to strength increase but results in the alteration of soil properties to enhance workability, as evidence in textural changes that accompany consistency improvements. Lime and cement have been meaningfully used for soil stabilization and modification (Reids and Brooks, 1999; Basha, et al, 2005; Eze-Uzomaka and Agbo, 2010; Joel and Agbede, 2011; Joel and Agbede, 2010). Laterite from Ikpayongo is not suitable for use as sub-base and base material and cannot be treated economically for use as pavement material with only Researchers have postulated that the use of cement for soil stabilization will be very effective when the plasticity index of the soil is less than 10 %, findings by (Garber and Hoel, 2010; Yoder and Witczak, 1975) indicate that where plasticity index value is greater than 10 % more cement will be required for effective stabilization, a situation that normally leads 50 Journal of Emerging Trends in Engineering and Applied Sciences (JETEAS) 6(1):49- 56 (ISSN: 2141-7016) geotechnical test on laterite samples obtained from Ikpayongo, treated with cement and lime. Results from such tests will be used in the determination of the most effective modifier for economic stabilization of Ikpayongo laterite with cement. to uneconomic stabilization of such soil. An alternative to the use of high percentage of cement is the use of lime as a modifier to reduce the plasticity index of the soil before stabilization with cement. Soil modification ability of cement and lime in this study will be assessed using the plasticity index value, with a minimum plasticity index value of 10 % being indices for effective modification as suggested by (Garber and Hoel, 2010). MATERIALS AND METHODS Laterite sample were collected from Ikpayongo, located at a distance of 22 kilometres from Makurdi, the capital of Benue State, Nigeria, along MakurdiOtukpo road. The borrow pit was located at a distance of 500 m and at an angle of 90° West from the centre line of the road. Disturbed samples were collected from the depth of 0.5 to 2.0 m after the removal of the top soil. Ordinary Portland cement and hydrated lime as obtained from the open market in Makurdi was used for the work. Analysis of chemical components of ordinary Portland cement and lime was carried out using x-ray analyzer together with Atomic Absorption Spectrophotometer (AAS). Advantages to be derived from the practical application of lime for soil modification according to (NLA, 2004) are “dry-up” of wet soil at construction sites to aid compaction, drying out of wet areas to help bridge across underlying spongy subsoil, provision of working table for subsequent construction, conditioning of soil through pretreatment for further stabilization with Portland cement or bitumen. Changes in the physical properties of soil observed when treated with cement is attributed to the hydration of calcium-silicates and calcium aluminates in Portland cement and pozzolanic reactivity between released lime and silica and alumina released from clay minerals. When hydrated lime is used in soil modification, the calcium ions from hydrated lime migrate to the surface of the clay particles and displace water and other ions. The soil becomes friable and granular, making it easier to compact. The plasticity index of the soil also decreases as well as its tendency to swell and shrink. This process is called flocculation and agglomeration, and occurs within minutes, this is the reaction that plays key role in soil modification. The reaction responsible for strength gain is the pozzolanic reaction, which occurs when silica and alumina released from clay mineral in a high pH environment react with calcium from the lime to form calcium-silicate-hydrates (CSH) and calcium-aluminate-hydrate (CAH). Which are cementitous products similar to those formed during cement hydration to form the matrix that contributes to the strength of lime-stabilized soil layers, and such reactions goes into days. Specimens of Soil samples used for different laboratory test were prepared by treating laterite with cement and hydrated lime in proportions of 0 %, 2 %, 4 %, 6 %, 8 % and 10 % by dry weight of laterite. Laboratory tests were performed on the sample obtained from Ikpayongo in accordance with BS1377 (1990) for the natural laterite and BS1924 (1990) for laterite mixed with cement and lime. California bearing ratio (CBR) tests were conducted in accordance with the Nigerian General Specification (1997) which stipulated that specimens be cured in the dry for six days then soaked for 24 hours before testing. Tests performed on Ikpayongo laterite sample mixed with cement, and hydrated lime, include Atterberg’s limits tests, compaction tests, Unconfined Compressive strength (UCS) tests and California bearing ratio tests. Compaction was carried out using the West African standard compactive effort, because it was the conventional energy level commonly used in the region and recommended by the Nigerian General Specification (1997). The compactive effort was achieved using energy derived from a rammer of 4.5 kg mass falling through a height of 45 cm in a 1000cm3 mould. The soil was compacted in five layers, each layer receiving 10 blows The resistance to loss in strength was determined as a ratio of the unconfined compressive strength (UCS) of specimens cured for 7 days under controlled conditions, which were subsequently immersed in water for another 7 days to the UCS of specimens cured for 14 days. The particle size distribution of Ikpayongo laterite was determined using the wet sieving method. The geotechnical and engineering properties of lateritic soils have been researched into in the northern, eastern, western and southern part of Nigeria. (Ola, 1983; Gidigasu and Kuma, 1987; Adeyemi, 2002; Oladeji and Raheem 2002; Bello, 2007; Bello and Adegoke; 2010), not much has been done on laterite found in the Benue trough, where Ikpayongo laterite deposit, found in the middle belt region of Nigeria is located. Since the properties of latertie varies with age of formation, location, and is not fixed, there is need for such a study, which is aimed at comparing the effectiveness of lime and cement in the modification of Ikpayongo laterite for effective and economic stabilization. The aim of the study will be achieved through the conduct of basic 51 Journal of Emerging Trends in Engineering and Applied Sciences (JETEAS) 6(1):49- 56 (ISSN: 2141-7016) lime used is summarized in Table 1. Summary of the result of test on the natural laterite is reflected in Table 2. RESULTS AND DISCUSSION The grain size distribution curves of Ikpayongo laterite is presented in (Figure 1), the chemical component of ordinary Portland cement and hydrated Table 1: Chemical Composition of CCR and Cement Oxides Concentration (%) Lime Cement CaO 67.08 64.0 MgO 1.26 1.94 Al2O3 0.50 5.75 Fe2O3 0.03 2.50 SiO2 1.54 20.4 MnO 0.05 - TiO2 0.32 - K2 O 0.05 0.61 Na2O 0.02 0.40 SO3 2.73 LOI: Loss on Ignition. The natural Ikpayongo laterite liquid limit value of 36 % shows that the material can be classified as having intermediate plasticity. This is based on Whitlow (1995) classification of materials with liquid limit less than 35 % being indicative of low plasticity, between 35 % and 50 % and between 51 % and 70 % being indicative of intermediate and high plasticity respectively, while values greater than 70 % is indicative of very high plasticity. The effect of cement and lime on the Atterberg’s limits values of Ikpayongo laterite treated with cement and lime is presented in (Tables 3 and 4), respectively. Table 3: Variation of Liquid limit, Plastic limit and Plasticity Index of Ikpayongo laterite with Cement Content Ikpayongo laterite was found to be an A-2-6 and GP soil by the AASHTO and Unified Soil Classification systems (USCS) respectively. The specific gravities of Ikpayongo laterite, cement and lime were determined as 2.69, 2.20, and 3.15 respectively. The geotechnical properties of Ikpayongo laterite clearly shows that it is only suitable for use as fill material and not sub-base and base material based on the Nigerian General Specification (1997). Soil stabilization is normally used to make such soil suitable for use as sub-base and base material. However, effective and economic stabilization with cement cannot be achieved based on report by (EzeUzomaka and Agbo, 2010; Joel and Agbede, 2011). This observation clearly shows that there is need for the modification of Ikpayongo laterite for effective and economic stabilization. Cement Content (%) Liquid Limit (%) Plastic Limit (%) Plasticity Index (%) Natural Moisture Content (%) 2 36 21 15 4 34 22 12 6 33 23 10 8 32 23 9 10 31 24 7 Table 4: Variation of Liquid limit, Plastic limit and Plasticity Index of Ikpayongo laterite, with Lime Content Lime Content (%) Liquid Limit (%) Plastic Limit (%) Plasticity Index (%) 0 36 20 16 2 35 22 13 4 32 23 9 6 31 24 7 8 30 25 6 10 29 25 4 The liquid limit of Ikpayongo laterite decreased with cement and lime content, while the plastic limit increase with cement and lime content, resulting in the decrease of plasticity index with cement and lime content. The trend observed with Atterberg’s limits indices and cement content can be attributed to the hydration reaction of cement. The trend observed with lime can be attributed to agglomeration of fine clay particles into coarse, friable particles by a base exchange with the calcium cation from lime displacing sodium or hydrogen ions, with a subsequent dewatering of the clay fraction of the laterite, referred to as cation exchange reaction. Table 2: Some Geotechnical Properties of Ikpayongo Laterite PROPERTY Percentage Passing BS Sieve No 200 (%) Liquid Limit, (%) Plastic Limit (%) Plasticity Index (%) AASHTO Classification USCS Classification Maximum Dry Density,Mg/m3 Optimum Moisture Content (%) Unconfined Compressive Strength KN/m2 California Bearing Ratio,% (after 24hrs soaking) Specific Gravity Colour 0 36 20 16 QUANTITY 45.5 36.0 20.0 16.0 A-2-6 GP 1.86 12.0 534 28 2.69 Reddish brown 7.24 The plasticity index value of Ikpayongo laterite decreased from 16 % to 7 % and 4 % respectively when treated with 10 % cement and lime content respectively. The minimum plasticity index value of 10 % to be attained by soil for effective stabilization with cement, recommended by (Garber and Hoel, 2010; Yoder and Witczak, 1975) was achieved with 52 LOI 26.85 1.20 Journal of Emerging Trends in Engineering and Applied Sciences (JETEAS) 6(1):49- 56 (ISSN: 2141-7016) the use of 6 % cement and 4 % lime content respectively. The use of hydrated lime to treat Ikpayongo laterite was more effective in reducing plasticity index than the use of cement, as more calcium ions was made available for reaction with the clay particles by the hydrated lime during cation exchange than the free lime release for reaction with clay particles during the hydration of cement. The implication of the result is that effective stabilization of Ikpayongo laterite with cement begins after the addition of 6 % cement, or after the addition of 4 % lime. to more moisture required for cation exchange and pozzolanic reaction of lime. Soil modification does not necessarily mean strength attainment, however, the strength criterion used in selecting materials for sub-base and base which is stability, measured in terms of the California bearing ratio (CBR) and unconfined compressive strength (UCS) which are indirect tests, will be used to evaluate the strength gain during modification process. Durability of material will be assessed using resistance to loss of strength measured using unconfined compressive strength specified by Ola (1974). Variation of maximum dry density and optimum moisture content of Ikpayongo laterite with cement and lime content is as presented in (Tables 5 and 6) respectively. The effect of lime and cement on the California bearing ratio (CBR), and UCS values of Ikpayongo laterite is presented in Tables 7 and 8 respectively. Table 5: Variation of Maximum Dry Density and Optimum Moisture Content of Ikpayongo laterite, with Cement Content Cement Content (%) Maximum Dry Density (MDD) Mg/m3 . Optimum Moisture Content (OMC) %. 0 2 4 6 8 10 1.86 1.88 1.90 1.93 1.95 1.98 12.0 12.5 13.0 14.0 15.0 16.0 Table 7: Strength Indices and Durability value of Ikpayongo Laterite treated with cement Cement content (%) 7 day UCS (kN/m2) 14 day UCS (kN/m2) 28 day UCS (kN/m2) Durability (%) CBR (%) Table 6: Variation of Maximum Dry Density and Optimum Moisture Content of Ikpayongo laterite, with Lime Content Lime Content (%) Maximum Dry Density (MDD) Mg/m3 . Optimum Moisture Content (OMC) %. 0 2 4 6 8 10 1.86 1.87 1.88 1.89 1.91 1.93 12.0 13.5 14.0 15.0 17.0 19.0 0 2 4 6 8 10 534 606 723 872 1044 1255 534 733 879 1059 1268.0 1518 534 861 1034 1240 1492 1788 0 20 38 55 65 75 28 70 90 100 120 135 7 day UCS= seven days Unconfined Compressive strength test. 14 day UCS= Fourteen days Unconfined Compressive strength test. 28 day UCS= Twenty-eight days Unconfined Compressive strength test. CBR = California Bearing ratio Table 8: Strength Indices and Durability value of Ikpayongo Laterite treated with Lime Maximum dry density of Ikpayongo laterite increased with cement and lime content. Increased maximum dry density may be due to a decrease in the surface area of the clay fraction of Ikpayongo laterite arising from the substitution of Ikpayongo laterite with cement or lime, the increase associated with lime can be attributed to the cation exchange and aggregation arising from the use of lime, while increase with cement is due to the hydration of cement. The maximum dry density of the untreated laterite increased from 1.86 Mg/m3 to 1.98 Mg/m3 and 1.93 Mg/m3 when treated with cement and lime respectively. Increase in maximum dry density with cement and lime content according to Amu et al (2011) is indicative of improvements in the soil properties. Optimum moisture content of Ikpayongo laterite increased from 12 % to 16 % and 19 % when treated with cement and lime respectively. The increase in optimum moisture content with cement is due to more moisture required for effective hydration of cement, while increase with lime can be attributed Cement content (%) 7 day UCS (kN/m2) 14 day UCS (kN/m2) 28 day UCS (kN/m2) Durability (%) CBR (%) 0 2 4 6 8 10 534 581 600 711 993 1090 534 642 835 900 1179.3 1297 534 700 988 1054 1287.9 1400 0 31 50 60 70 80 28 50 60 75 90 100 7 day UCS= seven days Unconfined Compressive strength test. 14 day UCS= Fourteen days Unconfined Compressive strength test. 28 day UCS= Twenty-eight days Unconfined Compressive strength test. CBR = California Bearing ratio The California bearing ratio of untreated Ikpayongo laterite increased from 28 % to maximum value of 135 % and 100 % when treated with 10 % cement 53 Journal of Emerging Trends in Engineering and Applied Sciences (JETEAS) 6(1):49- 56 (ISSN: 2141-7016) Table 9: Cost of Different percentages of lime and cement required for the modification of 1 Metric Ton (1,000 Kg) of Ikpayongo Laterite. and 10 lime respectively. Increase in California bearing ratio with cement can be attributed to the hydration reaction of cement, while that associated with the use of lime, can be attributed to the cation exchange and pozzolanic reaction of lime. Increase in California bearing ratio value with cement and lime content is an indication of the suitability of lime and cement for use in the modification of the laterite. The result also shows that the singular use of cement even up to 10 % cannot effectively stabilize the soil for use as base material as the maximum California bearing ratio values arising from their singular usage is less than the value of 180 % Specified by the Nigerian General Specification (1997) hence the need for modification. Additive Content (%) Cost of Cement N Cost of Lime N 0 2 4 6 8 10 0 720 1,440 2,160 2,880 3,600 0 2,800 5,600 8,400 11,200 14,000 Cost analysis clearly shows that the cost of using lime for soil modification is about 3.9 times the cost of using cement. Cost increases with cement and lime content, as the cost of modification with 10 % cement and 10 % lime is N 3,600 and N 14, 000 respectively. The cost of modifying Ikpayongo Laterite with 4 % lime, which is N 5,600 as against N 2,160 required with the use of 6 % cement for effective modification before stabilization with cement or other additives. Clearly shows that it is more economical to use 6 % cement for modification than 4 % lime, however other factors such as durability and cracks in layers should be considered before a final conclusion is drawn. The variation of 7 day UCS, 14 day UCS and 28 day UCS values with cement and lime content presented in Table 7 and 8, clearly shows that UCS value increase with days, cement and lime content. The maximum 7 day UCS value of 1255kN/m2 and 1090 kN/m2 obtained with the use of 10 % cement and lime respectively, is lower than the value of 1720 kN/m2 specified by Millard (1993) an indication that only cement or lime cannot effectively stabilized Ikpayongo laterite. CONCLUSIONS The use of cement and lime in the modification of Ikpayongo laterite has effect on the Atterberg’s limts value and strength indices of the laterite. The use of lime in the reduction of plasticity index is more effective than the use of cement, more cement is required for effective modification than lime as the plasticity index value of Ikpayongo laterite decreased from 16 % to 7 % and 4 % respectively when treated with 10 % cement and 10 % lime respectively. Differences in strength observed with CBR and UCS values can be attributed to the concentration of cementing gel form, during the hydration of cement, which is higher than that obtained from the pozzolanic reaction of lime, in addition to the hardening process of cementing gel being faster with the use of cement than with lime. A situation responsible for higher strength values observed with the use of cement than was observed with lime. Strength indices value of Ikpayongo laterite modified with cement is higher than values obtained with modification with lime, as the California bearing ratio and 7 day UCS values increased from 28 % to 135 % and 100 % respectively when treated with 10 % cement and lime respectively, while the 7 day UCS values increased from 534 kN/m2 to 1255 kN/m2 and 1090 kN/m2 respectively, when treated with 10 % cement and lime respectively. The resistance to loss of strength of Ikpayongo laterite which disintegrated inside water in the absence of a binder increased from 0 % to 75 % and 80 % respectively when treated with 10 % cement and 10 % lime respectively. Resistance to loss of strength value of 25 % attained at 10 % cement is higher than the maximum loss of strength value of 20 % recommended by Ola (1974). An indication that a modifier or more cement is required for effective treatment of Ikpayongo laterite with cement. It is worthy of note that the water retarding ability of lime is higher than that of cement, a situation responsible for higher durability values associated with lime application. Economic analysis clearly shows that it is more economical to modify soil with cement than lime, however, where cement is used as the stabilizer high cement content might lead to cracks in the stabilized layer, hence the recommendation of the use of lime in such situation. Cost analysis of using cement and lime in the modification of Ikpayongo laterite is as presented in (Table 9). The cost of 25 kg of lime is N 3,500, the cost of 1 kg of lime will be N 140. The cost of 50 Kg bag of cement is N 1,800, the cost of 1 Kg of cement will be N 36. Based on results of test, 4 % lime is recommended for effective modification of Ikpayongo laterite before stabilization with cement. 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