Μm Sieve Research Articles

Effect of the calcinations temperatures of phosphate washing waste on the structural and mechanical properties of geopolymeric mortar

The phosphate industry is facing serious environmental problems. This issue is caused by the waste after the extraction of the phosphate ore. The waste termed as phosphate washing waste (PWW) was filtered and dried at 105 °C for 24 h to remove the water. The dried PWW was milled, sieved in a 100 µm sieve and characterized by X-ray fluorescence (XRF). The resulting waste was calcined at 600, 700 and 800 °C, the calcined and uncalcined waste were investigated by X-ray powder diffraction (DRX), Fourier transform infrared (FTIR), simultaneous differential thermal and thermogravimetric analyses (DSC-TG) and scanning electron microscope (SEM). The PWW was activated with sodium hydroxide (NaOH) and sodium silicate to produce geopolymeric materials. It was found that the calcination temperature and the extra water added to the mixture to assure the good workability play an important role on the development of the system’s workability and compressive strength.

Impact of Gyration Reduction and Design Specification Changes on Volumetric Properties of Virginia Dense-Graded Asphalt Mixtures

In 2015, the Virginia Department of Transportation (VDOT) proposed changes to their specification for asphalt mix design. The changes incorporated a reduction of design gyrations from 65 to 50; the addition of constraints on the No. 4 (4.75 mm) and No. 30 (600 µm) sieves; and adjustments to the production value for voids filled with asphalt and minimum voids in mineral aggregate. Before these modifications were fully adopted, a study was performed to assess the effect of the changes on mixture properties and laboratory performance. Eleven pairs of asphalt mixtures were evaluated; the pairs consisted of a typical VDOT 65-gyration mixture produced under the specification current at the time and a companion 50-gyration mixture designed and produced in accordance with the proposed specification. Mixtures were evaluated to determine the effect of the design parameters on volumetric properties, gradation, and permeability. The changes had very little effect on volumetric properties or gradation. Permeability effects were mixed, with 9.5 mm nominal maximum aggregate size mixtures requiring greater compaction to meet permeability requirements and 12.5 mm nominal maximum aggregate size mixtures showing improved permeability even at higher air-void contents. For the 50-gyration mixtures, core air voids were reduced, indicating the potential for increased durability attributable to improved densification in the field.

EFFECT OF GRADATION AND REPLACEMENT LEVEL ON ALKALI-SILICA REACTIVITY OF MINERAL FILLERS

Mineral fillers are used in concrete for a number of reasons, which include achieving self-consolidation properties. Different fillers are available depending on the type of the original rock. Alkali-silica reaction might occur if the filler is produced from a reactive rock. The present research focuses on evaluating the applicability of the current accelerated mortar bar test, described in ASTM C1260 and CSA A23.2-25A, in evaluating their reactivity. Three different fillers are used: a calcium-carbonate filler, a carbonate silica filler with 27% SiO2, and a siliceous filler produced from reactive aggregate. Two different gradations of the filler obtained from reactive aggregate are tested: 1) Gradation finer than 75 µm; 2) Gradation with 30% passing 150 µm sieve but is retained on 75 µm sieve and remaining 70% passing 75 µm. Results showed that the calcium-carbonate filler and the carbonate silica filler did not show any expansion higher than the non-reactive sand, while the filler obtained from reactive aggregate did not show expansion higher than the control at 14 days for both gradations, with the expansion showing at later age. This might be due to the high surface area of fillers and the reduced permeability affecting the rate of expansion. Hence, the need to extend the testing period beyond the 14-day specified in the standard to be able to see the expansion.

Swell and Compressibility of GGBS–Clay Mixes in Lumps and Powders: Effect of 4% Lime

Chemical stabilization is one of the most successful among the techniques devised for reducing the volumetric changes of expansive soils. Lime and cement, fly ash and pond ash, calcium chloride and calcium silicate are some of the additives used for stabilizing expansive soils. This paper presents the influence of ground granulated blast furnace slag (GGBS) on swell-compressibility characteristics of a remoulded expansive clay passing 4.75 mm sieve. FSI, rate and amount of heave, swell potential (S%), swelling pressure (ps), coefficient of compressibility (av), compression index (Cc) and linear shrinkage (LS) of GGBS–clay blends were studied varying the GGBS content such as 0, 4, 8 and 12% by dry weight of the soil. It was observed that swellability and compressibility of the expansive clay decreased with increasing GGBS content. At 12% GGBS, the amount of heave was the lowest. The paper compares the effect of 12% GGBS on clay lumps passing 4.75 mm sieve and clay powder passing 425 µm sieve. While swell potential (S%) was found to be more for clay powder than for clay lumps at 12% GGBS, swelling pressure was higher for clay lumps than for clay powder. The paper also presents FSI data on clay–lime blends with varying lime content. As 4% lime resulted in the highest reduction of FSI, two more series of swell-consolidation tests and FSI tests were conducted on GGBS–clay blends to which 4% lime was added. Interesting phenomena were observed which the paper discusses in detail.

EVALUATION OF A MODIFIED BIOMATERIAL OF TYMPANOTONUS FUSCATA SHELL POWDER II: FORMULATION OF PYRIMETHAMINE AND PYRIDOXINE HYDROCHLORIDE TABLETS

A novel modified biomaterial of periwinkle shell powder, MBPSP was developed from Tympanotonus fuscata . It was assessed as a bulking agent in the formulation of pyrimethamine and pyridoxine hydrochloride tablets adopting dicalcium phosphate dihydrate (DCP) as a standard. A 100 g of the ground periwinkle shell was broken down in 166.0 ml of 2 M hydrochloric acid, clarified and treated with 5 M sodium hydroxide. The thick white precipitate obtained was washed severally and to it, ortho-phosphoric acid was dropped in bits until a thick, dehydrated bulk was attained which was dried at 60 o C and classified with 250 μm sieve. The product was coded MBPSP. Two batches of granules containing pyrimethamine (25 mg) and pyridoxine hydrochloride (50 mg) were generated by the wet granulation employing MBPSP alongside DCP. The granules were lubricated with magnesium stearate and talc and compacted into tablets at 7.55kN using a 10.50 mm diameter die and flat-faced punch fixed in a hydraulic hand press. The tablet produced were evaluated using the British Pharmacopoeia specifications. The weight variation for the pyrimethamine or pyridoxine hydrochloride tablets containing MBPSP or DCP were 0.06, 0.1, 0.097 and 0.143 % respectively. The total drug content for the individual lots of tablets for either pyrimethamine or pyridoxine hydrochloride was within 85.00-115.00 % of their label claim. Higher mechanical strength were noted for the batch of tablets manufactured with DCP and containing pyrimethamine and pyridoxine hydrochloride than MBPSP. Though the entire batches of tablets for the two drugs manufactured with either MBPSP or DCP disintegrated in less than 5.00 min with no significant difference in their individual disintegrating time (p>0.05), pyridoxine hydrochloride tablets prepared with DCP disintegrated in lesser time when compared to MBPSP (p<0.05). Only the pyrimethamine tablets prepared with MBPSP attained 75.00 % drug release in 45.00 min in line with the United States Pharmacopoeia (USP) criteria. Therefore, MBPSP could be another very useful bulking agent in the formulation of pyrimethamine immediate-release tablets by the wet granulation technique. Keywords : Modified biomaterial, Tympanotonus fuscata, periwinkle, shell, pyrimethamine, pyridoxine hydrochloride, tablet.

Palm Oil Fuel Ash (POFA) and Eggshell Powder (ESP) as Partial Replacement for Cement in Concrete

This study is an attempt to partially replace Ordinary Portland cement (OPC) in concrete with palm oil fuel ash (POFA) and eggshell powder (ESP). The mix proportions of POFA and ESP were varied at 10% of cement replacement and compared with OPC concrete as control specimen. The fineness of POFA is characterized by passing through 300 μm sieve and ESP by passing through 75 μm sieve. Compressive strength testing was conducted on concrete specimens to determine the optimum mix proportion of POFA and ESP. Generally the compressive strength of OPC concrete is higher compared to POFA-ESP concrete. Based on the results of POFA-ESP concrete overall, it shows that the optimum mix proportion of concrete is 6%POFA:4% ESP achieved compressive strength of 38.60 N/mm2 at 28 days. The compressive strength of OPC concrete for the same period was 42.37 N/mm2. Higher water demand in concrete is needed due to low fineness of POFA that contributing to low compressive strength of POFA-ESP concrete. However, the compressive strength and workability of the POFA-ESP concrete were within the ranges typically encountered in regular concrete mixtures indicating the viability of this replacement procedure for structural and non-structural applications.

Evaluation of the impact caused by handling procedures on the embryonic development of the sea urchin Paracentrotus lividus (Lamarck, 1816)

Evaluation of the impact caused by handling procedures on the embryonic development of the sea urchin Paracentrotus lividus (Lamarck, 1816)

PM 7/28 (2) Synchytrium endobioticum

Specific scopeThis Standard describes a diagnostic protocol for Synchytrium endobioticum.This Standard should be used in conjunction with PM 7/76 Use of EPPO diagnostic protocols.Specific approval and amendmentApproved in 2003‐09. Revision approved in 2017‐06.

Electrodialytic extraction of Cr from water-washed MSWI fly ash by changing pH and redox conditions

Electrodialytic process offers a range of possibilities to waste management by electrodialytic separation (EDS) of heavy metals, depending on how the process is designed. Using three EDS cell setups (two two-compartment and one three-compartment) and their combinations, the extraction of Cr from municipal solid waste incineration fly ash by changing pH and redox conditions was investigated in the present work. The experiments were designed into single, two and three steps, based on the number of setups (by changing EDS cells) or effective setups (by shifting working electrode pairs) used. Prior to EDS the ash studied went through pretreatments such as water-washing and dry-sieving with a 50 µm sieve. The results showed that Cr was strongly bound in the ash, and the major fraction remained bound after the different treatments. Two/three-step treatment, which obtained the maximum Cr extraction rate of 27.5%, is an improvement on the single-step that extracted maximum 3.1%. The highest extraction was obtained due to the combined extraction of Cr(III) under low pH (accompanied with high redox) conditions and Cr(VI) under high pH (low redox) conditions subsequently. The Cr leaching from the treated ashes with acidic pH was lower than from those with alkaline pH; after the three-step treatment, Cr leaching was much lower from the coarse fraction (> 50 µm), as compared to the fine (≤ 50 µm) or the unsieved ash. As for the coarse fraction, two/three-step treatment reduced the leaching of Cr compared to the single-step in the same pH range (either acidic or alkaline).

Influence of Mechanically Activated Electric Arc Furnace Slag on Compressive Strength of Mortars Incorporating Curing Moisture and Temperature Effects

In this study, the influence of mechanically activated electric arc furnace slag (EAFS) was investigated through compressive strength tests on 50 mm mortar cubes. The objective was to convert the wasteful EAFS into a useful binding material to reduce the cement content in concrete without compromising strength and economy. Four different groups of mortar were cast which include control mortar, reference fly ash mortar, mortar containing EAFS to determine its optimum fineness and replacement with cement, mortar blend containing fly ash and EAFS of optimum fineness. EAFS were identified with respect to its fineness as slag ground (SG), slag-fine (SF) 100% passing 75 µm sieve, and slag-super-fine (SSF) 100% passing 45 µm sieve. Compressive strength was measured according to ASTM C109. Specimens were cured under different temperatures and moisture to incorporate the effects of normal and hot environmental conditions. Compressive strength of mortars increases with fineness of EAFS and its strength activity index matches the ASTM C989 blast furnace slag (BFS) Grade 80 up to 30% cement substitution and Grade 100 when 10% cement substituted with SSF. The influence of curing temperatures was also significant in mortars containing SG or 10% SF where strength decreased with increasing curing temperature. However, a 20–30% and 20% cement substitution with SF produced strength comparable to control and reference fly ash mortars under moderate (40 °C) and high curing temperature (60 °C), respectively. The utilization of EAFS as binder in concrete may reduce needs for cement, as well as save environment and natural resources from depletion.

Chopping Hay Before Feeding Does Not Influence Fecal Particle Size, Blood Variables, or Water Intake in 3-Year-Old Arabians

Previous work suggested that feeding chopped roughage, rather than long-stem, may influence thermoregulation during prolonged exercise, potentially by reducing hindgut particle size, thereby influencing water dynamics. This study aimed to determine if chopping hay affects fecal particle size (FPS), packed cell volume (PCV), plasma total solids (TS), and fecal dry matter (FDM). Six 3-year-old Arabians were divided into two groups and initially, for acclimation, fed either long-stem alfalfa hay or the same hay chopped (3–6 cm length) for a week each in a cross-over design; in weeks 3 and 4, this cross-over repeated. On days 6 and 7 of weeks 3 and 4, water consumption was measured over 48 hours, feed intake time was recorded, and PCV plus TS were measured at 0, 30, 60, 90, 120, 150, and 180 minutes after feeding. Fecal samples were collected each morning during weeks 3 and 4 to determine FDM and FPS. Packed cell volume and TS increased over the 3-hour sampling period (P < .01), but chopping the hay had no effect on the hay intake time, PCV, or TS. Water consumption and FDM did not differ between treatments (P = .9; P = .24) and there was no effect of treatment on FPS (P = .50). Only 10% of the fecal particles did not pass through the largest 2.36 mm sieve and 44% passed through the 150 μm sieve, suggesting marked reduction in particle size during the digestive process regardless of original hay intake length. Chopping hay did not have an impact on measured variables including FPS.

The effect of mechano-chemical activation and surface treatment of limestone filler on the properties of construction composites

Abstract The effect of the combined actions of milling and hydrophobization procedures applied in construction composites synthesis was investigated. The mortars were prepared with cement (CEM I 42.5) and calcite aggregate complying the standard 1:3 mix ratio. The limestone filler (10 wt%) was added to the mixture upon its mechano-chemical activation in an ultra-centrifugal mill. The activation variables (milling time, rotor velocity, sieve mesh size) were altered to achieve the optimal quality of the powder. The treatment was optimized via chemometric tools. The r2 values (0.955–0.998) of second order polynomial models accurately predicted the output and the Standard score analysis chose the optimal activation parameters: 4.25 min; 48.58 m/s and 80 μm sieve. The selected filler and all three aggregate fractions were coated with stearic acid via dry procedure. The mortar mixes, prepared with uncoated (M1) and coated (M2) aggregate and filler, were cured for a period of 28 days during which compressive strength and water absorption were monitored. The dimensional changes in mortars were estimated via TMA dilatometer measurements. Thermo-analytical methods (DTA/TGA) were applied in the thermal behavior analysis. Mineralogical and morphological changes in the structure of hardened composite were detected by XRD and SEM, respectively. Limestone aggregate led to lower final compressive strengths in mortar, but it produced an infinitesimally small shrinkage at 1000 °C. The hydrophobization via stearic acid initiated the decrease in water absorption and formation of needle-like micro-network that filled structural voids reducing open porosity. The assessment of the effects of limestone utilization as a filler and as an aggregate on the mortar performances confirmed that this novel water-repellent composite is applicable in structural design.

Multivariate Analysis Based on Nutritional Value, Antinutritional Profile and Antioxidant Capacity of Forty Chickpea Genotypes Grown in India

Background: Chickpea (Cicer arietinum L.) is an important pulse crop with several potential health benefits. Providing an affordable alternative to animal protein, the chickpea seed is consumed as food in various platters. However, bioavailability of seed proteins is usually low. This seems due to the presence of antinutritional factors, such as phytates, trypsin inhibitors and tannins. Objectives: This study has been conducted to evaluate the multivariate analysis of nutritional and antinutritional aspects of 40 chickpea genotypes. Methods: seeds were maintained at 4°C with 40% relative humidity. Seeds were grinded in a grinder and the contents were passed through 80 μm sieve. Powdered seed samples were first defatted using chilled acetone and air dried. Nutritional and other phytochemical analysis were performed under ambient conditions of temperature and humidity. Results: The seeds exhibit an average nutritional content of total protein (≥ n110.38 mg-1 100 g), total free amino acids (≥ 292.28 mg-1 100 g) and nutritional minerals like Fe (≥ 0.66 mg-1 100 g) and Zn (≥ 0.59 mg-1 100 g). The multivariate analysis for all the chickpea genotypes studied, based on their principal components, show unique position according to their nutritional status. Moreover, hierarchical clustering agglomerative genotypes as basis for genotypes, grouped into two major clusters of MC-1 and MC-2. The study revealed that chickpea genotypes exhibit divergent nutritional and antinutritional properties. Conclusion: Based on the present study and evaluation, the genotype selection for future breeding programmes so as to develop nutritionally elite cultivar can be planned.

Optimization of the EMI shielding effectiveness of fine and ultrafine POFA powder mix with OPC powder using Flower Pollination Algorithm

In order to solve the electromagnetic interference (EMI) issue and provide a new application for palm oil fuel ash (POFA), POFA was used as the cement filler for enhancing the EMI absorption of cement-based composites. POFA was refined by using water precipitation for 24 hours to remove the filthiness and distinguish the layer 1 (floated) and layer 2 (sink) of POFA. Both layers POFA were dried for 24 hours at 100 ± 5 °C and grind separately for sieve at 140 μm (Fine) and 45 цш sizes (Ultrafine). The micro structure and element content of the both layers POFA were characterized by scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS) respectively. The results showed layer 1 POFA has potentialities for EMI shielding effectiveness (SE) due to its higher carbon content and porous structure. The study reveals that EMI SE also influenced by the particle size of POFA, where smaller particle size can increase 5 % to 13 % of EMI SE. When the specimen consists of 50% POFA with passing through 45 μm sieve, the EMI was shield -13.08 dB in between 50 MHz to 2 GHz range. Flower Pollination Algorithm (FPA) proves that POFA passing 45 μm sieve with 50% mixed to OPC is optimal parameter. The error between experimental and FPA simulation data is below 1.2 for both layers POFA.

All-Solid-State Battery Electrode Sheets Prepared by a Slurry Coating Process

Some basic but important guidelines for the development of sheet-type all-solid-state batteries using a practical slurry coating process are described in this paper. Li3PS4 glass powder that had been passed through a 25 μm sieve was prepared. Positive and negative electrode sheets with capacities of more than 1.5 mAh cm−2 were developed. An all-solid-state full cell was constructed using the electrode sheets and the self-standing solid electrolyte sheets. The energy density of the cell was ca. 155 Wh kg−1, where the weight of the current collectors and the exterior package was excluded from the weight for calculation.

PROPERTIES OF CEMENT PASTE AND CONCRETE CONTAINING CALCIUM CARBIDE WASTE AS ADDITIVE

This paper assessed the effect of calcium carbide waste (CCW) as additive on the properties of cement paste and concrete. The CCW used was sourced from a local panel beating workshop. It was sundried and sieved through a 75 µm sieve and characterized by X-Ray Fluorescence (XRF) analytical method. The consistency, setting times and drying linear shrinkage of cement paste with CCW addition of 0, 0.25, 0.5, 0.75 and 1.0 %, respectively by weight of cement were investigated in accordance with standard procedures. The slump values of fresh concrete containing CCW as additive and of 1:2:4 mix ratio and water-cement ratio of 0.5 was determined. A total of sixty numbers of 150 mm cubes of hardened concrete were tested for compressive strength at 1, 3, 7, 28 and 56 days of curing in accordance with standard procedures. The concrete compressive strength was also modeled using Minitab statistical software based on linear regression technique. The results of the investigations showed that CCW was predominantly of calcium oxide (95.69 %) and a combined SiO2, Al2O3 and Fe2O3 content of 3.14 %. The addition of CCW in cement decreased drying shrinkage (100 %), initial setting time (78 %) and final setting time (57 %), but increased consistency (14 %) at 1.0 % CCW content. The addition of CCW in concrete also showed slight increase in slump (6.5 %) and increase in compressive strength with increase in CCW additive up to 0.5 % and decrease in compressive strength with further increase in CCW content. The 28 days compressive strength of concrete with 0.5 % CCW content was 6.4 % more than normal, while that of concrete with 1.0 % CCW content was 14.9 % less than normal. The compressive strength model of CCW-concrete was developed with R2 value of 0.830 and could be used to predict concrete compressive strength. http://dx.doi.org/10.4314/njt.v36i1.4

PROPERTIES OF CEMENT PASTE AND CONCRETE CONTAINING CALCIUM CARBIDE WASTE AS ADDITIVE

This paper assessed the effect of calcium carbide waste (CCW) as additive on the properties of cement paste and concrete. The CCW used was sourced from a local panel beating workshop. It was sundried and sieved through a 75 µm sieve and characterized by X-Ray Fluorescence (XRF) analytical method. The consistency, setting times and drying linear shrinkage of cement paste with CCW addition of 0, 0.25, 0.5, 0.75 and 1.0 %, respectively by weight of cement were investigated in accordance with standard procedures. The slump values of fresh concrete containing CCW as additive and of 1:2:4 mix ratio and water-cement ratio of 0.5 was determined. A total of sixty numbers of 150 mm cubes of hardened concrete were tested for compressive strength at 1, 3, 7, 28 and 56 days of curing in accordance with standard procedures. The concrete compressive strength was also modeled using Minitab statistical software based on linear regression technique. The results of the investigations showed that CCW was predominantly of calcium oxide (95.69 %) and a combined SiO 2 , Al 2 O 3 and Fe 2 O 3 content of 3.14 %. The addition of CCW in cement decreased drying shrinkage (100 %), initial setting time (78 %) and final setting time (57 %), but increased consistency (14 %) at 1.0 % CCW content. The addition of CCW in concrete also showed slight increase in slump (6.5 %) and increase in compressive strength with increase in CCW additive up to 0.5 % and decrease in compressive strength with further increase in CCW content. The 28 days compressive strength of concrete with 0.5 % CCW content was 6.4 % more than normal, while that of concrete with 1.0 % CCW content was 14.9 % less than normal. The compressive strength model of CCW-concrete was developed with R 2 value of 0.830 and could be used to predict concrete compressive strength. http://dx.doi.org/10.4314/njt.v36i1.4

Production and Characterisation of Microfine Sized Palm Oil Fuel Ash (POFA) Originated from Bau, Lundu Palm Oil Mill

This paper investigates an effective and economical way for laboratory scale production of micro fine sized palm oil fuel ash (POFA) using an electric powder grinder. The raw POFA obtained from the palm oil mill is initially grinded by using Los Angeles abrasion machine, and then sieved using 150 μm sieve before it is burned in a furnace at 500°C. The burned POFA is then grinded using electric powder grinder to obtain the targeted micro fine sized. The physical, morphological and chemical properties of the micro fine sized POFA produced are analysed in the form of cement paste using Particle Size Analyzer (PSA), nitrogen sorption by using BET method, Fourier Transform Infrared Spectroscopy (FT-IR) and Scanning Electron Microscopy (SEM) with Energy Dispersive Spectroscopy (EDS). The results show that 96% micro fine sized POFA is produced when using the optimum grinding process. The microstructural analyses of cement paste with 20% micro fine sized POFA replacement give the optimum results that contribute to higher compressive strength. The overall results of this research show that the optimum grinding process by using electric powder grinder is relevant and can be used as pioneering work in the concrete production industry

Evaluación del efecto del envejecimiento del cemento asfáltico 80-100 modificado con lignina Daniella Rodríguez U, Cristian Rodríguez, Sindy R

Esta investigación presenta un análisis de los resultados obtenidos de un asfalto modificado con lignina, un polímero abundante y de fácil acceso debido a su origen natural y su bajo costo de obtención el cual se crea mediante el proceso de fotosíntesis, compone el 30% de carbono orgánico no fósil y de un cuarto a una tercera parte de la masa seca de la madera, cumple con una función fundamental que se caracteriza por dar soporte estructural, impermeabilidad y resistencia contra agentes microbiológicos y estrés oxidativo. Esto hace que se convierta en un polímero muy resistente a la degradación. Para la mezcla modificada se utilizó un asfalto 80-100, y lignina producto de un desecho industrial papelero. El método empleado para esta investigación fue a partir de los ensayos de penetración y punto de ablandamiento (anillo y bola), consideradas como pruebas funda-mentales cuando se busca producir mezclas que presenten mayor temperatura de ablandamiento y menor temperatura de fractura. Con la lignina se utilizaron 6 porcentajes distintos; 5%, 10%, 15% y 20% en 400 gramos de asfalto 80-100. La lignina fue tamizada en el tamiz de 75 µm con el fin de obtener una mezcla homogénea y evitar grumos; el tiempo de mezcla fue de 30 minutos por cada porcentaje y la temperatura se manejó en un rango de 125°C a 135°C para prevenir la aparición de burbujas de aire.

Effect of Fine Percentage on the Properties of Sub-base Material

Finding sub-base material as per required specifications is a major issue in many parts of Sri Lanka. Therefore, in some cases, crushed stone is used as an alternative to sub-base material. Since good quality material is scarce, it is worthwhile to study the use of marginal materials to ensure sustainable development of the highway sector. The specification used in Sri Lanka for road constructions is the Standard Specification for Construction and Maintenance of Roads and Bridges (SCA/5) (SSCM) (ICTAD, 2009). Sub-base material is classified as lower sub-base material and upper sub-base material according to their Liquid Limit (LL), Plastic Limit (PL), Maximum Dry Density (MDD), California Bearing Ratio (CBR), and Sieve Analysis. A questionnaire survey was conducted among those engaged in the construction industry, to collect information on sub-base construction and on issues connected with the current specification relating to the passing percentage of the fine fraction. As a result, an experimental study was conducted by altering the fine fraction of soil from 0% to 40%. It was also verified whether the grading band of No.200 sieve passing can be relaxed up to a certain percentage if the soil sample satisfies the specified CBR, Plasticity Index (PI) value and swell percentage requirement. It was found that the proposed changes have been adopted in AASHTO and Road Note 31 specifications. Furthermore, linear regression models were fitted to assess the CBR of material in relation to fine fractions (percentage passing of 425 μm, 300 μm, 75 μm sieves). These passing percentages were identified as the most important percentages in predicting the CBR of the soil tested.