Dry Density Values Research Articles

Hydrological, mineralogical and geotechnical characterisation of soils from Douala (coastal, cameroon): potential used in road construction

The life span of pavements in coastal areas is diminutive due to high traffic levels. In this study, soils from different localities (Dibamba, Bekoko and Lendi) in the Douala coastal area were investigated, for their hydrological, mineralogical and geotechnical properties. This is to determine their potential used as raw material in the sub-base or base layer for road construction. Hydrological analysis of data for the past twenty years revealed that the average annual temperature stood at 27.5 °C with average precipitation of about 433.1mm. Average relative humidity was 82% throughout the year. XRD/XRF analysis were carried on the different soil samples and revealed quartz ranges from 52 -72%, kaolinite (20–35%); goethite (4–5%), anatase (3–4%) and feldspar (0–4%). The mineralogical content of these soils was similar to silico-aluminous-ferruginuos-titanous soils characterized by high silica content (43.52–66.4%), moderate alumina (13.5–31%), low content of Fe2O3 (2.5–3.2%) and TiO2 (1.2–2.02%). The silica/sesquioxide ratio of the various sample ranged from 1:1 to 1:3 indicating that the samples from Bekoko are non-lateritic, those of Dibamba are lateritic while the soils from Lendi are true laterite soils. The laterites are suitable for the sub base layer of road pavements. Specific density of investigated samples ranges between 2.12 and 2.32 g/cm3 a result of low degree of laterization. The percentage of clay in the fine fraction for samples from Bekoko, Dibamba and Lendi stood at 24.5%, 19.0% and 14.9% respectively. These values are lower than 35% which is the standard value recommended for sub-base material by the CEBTP. The Atterberg limits range from 11.50 to 22.4% hence samples from Lendi are the low plasticity while those of Bekoko and Dibamba have a moderate plasticity with low swelling potentials. Soil samples from Dibamba and Bekoko were of the A-7-6 group while Lendi soil samples were of the A-7-5 group which correspond to clayey soils and hence classified as poor materials for road construction according to American Association of State Highway and Transportation Officials (AASHTO) classification. The Unified Soil Classification System (USCS) revealed that, the majority of samples collected in the study area belonged to the SM group (silty sand) except DIB1 and LEN1 samples which pertain to SC group (clayey sand). The average of the maximum dry density (MDD) values stood at 1.9 g/cm3 with an average moisture content of 11% corresponding to the lower limit recommended for the use as sub-base materials. The value of CBR range between 8.6 and 28,2% which correspond to class S4 and can be used as raw material for the foundation layer of low traffic (T1) in the CEBTP standard. If those materials are treated with coarse gravel, cement and/or bitumen, they can be used on sub-base and base layer of high traffic (T2/T3).

Performance Testing Of Sand And Lime As Subgrade Stabilizing Materials For Roads

Soil stabilization is a method used to increase the carrying capacity of a layer of soil, by giving special treatment to that layer of soil. Soil is one of the factors that can affect the structure of road construction. The CBR value is one of the parameters to determine soil carrying capacity, if the CBR value is high then the soil carrying capacity is good, whereas if the CBR value is low then the soil needs to be stabilized. The purpose of this study was to determine the characteristics and classification of soil, determine the results of the grain gradation test, sieve analysis and hydrometer analysis, consistency limits (Atterberg limits) before and after stabilization, compaction results (Proctor) before and after stabilization, determine the CBR value of the soil before and after stabilization. This research included water content test, wet soil unit weight test, specific gravity test, sieving analysis, hydrometer analysis, Atterberg limit test, compaction test (Modification), and immersion CBR test and CBR without immersion. In this test, variations in the addition of 20% sand and lime content were 5%, 10% and 15% of the dry weight of the soil. From the test results, the original soil samples showed soil classification A-7-6 according to AASHTO with maximum dry density (MDD) values of 1.70 gr/cm3 1 day curing, 1.64 gr/cm3 7 days curing and 1.77 gr/cm3 for 14 days curing, there was an increase in the value of the maximum dry density (MDD) in the original soil stabilized with 20% sand and 5% lime, a value of 1.78 gr/cm3 was obtained for 1 day curing, 1.86 gr/cm3 cm3 7 days curing and 1.82 gr/cm3 14 days curing. From the test results, the original soil samples showed soil classification A-7-6 according to AASHTO with CBR values of soaked 3.15% 1 day curing, 3.68% 7 days curing and 4.21% 14 days curing, there was an increase Soaked CBR values on native soil stabilized with 20% sand and 5% lime obtained CBR values of 37.19% at 1 day curing, 42.10% 7 days curing and 30.29% 14 days curing.

Measurement of Physical Parameters for Transient Seepage Assessment of Levees

Abstract An embankment was instrumented and monitored as part of a multiyear project to assess appropriate pore-water pressure distributions and soil water retention curves for use as initial conditions in transient seepage analyses. The increased use of unsaturated soil mechanics and transient seepage has led to the need for practical methods of assigning accurate properties and initial conditions in these types of analyses. Monitoring results were validated against published pore-water pressure measurements collected from multiple embankment studies. The collected distributions showed nonlinear behavior in near-surface embankment soils due to infiltration and evapotranspiration processes. Seasonal variations in pore-water pressure and the soil moisture deficit were shown to correlate at the monitoring site. The seasonal response of the embankments exhibited a large variation in pressures between summer and winter. Assessment of flood occurrence showed the distribution of pore pressures during flood loading was typically near −10 kPa at a depth of 2 m at the onset of the flood. Laboratory soil water retention testing of undisturbed samples collected from the embankment showed that when compared with field measurements, they overestimated the field response for the considered initial water content and dry density values. Also, comparisons between hydrostatic pore pressures above the phreatic surface showed that at soil moisture deficits greater than 20 mm, the difference between the measured and hydrostatic pore pressures greatly increased. The laboratory and monitoring results were used to provide practical methods of assigning representative pore-water pressure distributions and material properties necessary for performing transient seepage analyses. These results will aid in more accurate transient seepage analyses of flood control embankments.

Direct Shear Strength Characteristics in Unsaturated Compacted Soil Surface Coverage on Pb(II)-Polluted Tailings Reservoir under Low Normal Stress

Mining activities generate a large amount of solid waste called tailings, and it often contains a certain number of heavy metals, depending on the different types of minerals. To avoid disasters caused by the diffusion of tailings and their infiltration into surface water, mines often use tailings ponds as a surface coverage structure. This study mainly focused on the shear strength of surface coverage isolation layer soil under low normal stress. The soil isolation layers with different values of dry bulk density, water content, bentonite content, and Pb(II) ion concentration were treated with direct shear strength under normal stress at 12.5, 25, 50, and 100 kPa. It was found that when the dry bulk density was increased from 1.1 g/cm3 to 1.3 g/cm3, the shear strength increased by 49.3%~117.2%, and when the water content was decreased from 24% to 16%, the shear strength increased by one to three times. With the addition of bentonite in proportions from 18% to 30%, shear strength increased by 1.9 to 116.9 kPa, and the degree of improvement was related to both dry bulk density and water content; the specimens with bentonite added were more sensitive to Pb(II) ion concentration, and when the specimen with 24% bentonite addition was compared with the specimen without the addition of bentonite, both under a Pb(II) ion concentration of 5 mg/L, the shear strength decreased by 8.1~35.6 kPa, the internal friction angle decreased by 0.5~9.7°, the cohesion force decreased by 5.8~37.7 kPa, and the shear modulus decreased by 5~12 kPa/mm. Therefore, in order to maintain good mechanical properties in the surface covering structure, it is necessary to maintain a high dry bulk density, low water content, and bentonite content of no less than 24%.

Comparison of the Physical and Mechanical Properties of Construction Materials Added Profillite and Zeolite

Bu araştırmada bazalt agregalı yapı malzemesine zeolit ve profillit katkıları eklenerek performans etkileri karşılaştırılmıştır. Malzeme olarak, Adana/Osmaniye bazaltları, Malatya/Pütürge profillitleri ve Manisa Gördes zeolitleri kullanılmıştır. Beton deneylerinde Su-çimento oranı sabit tutularak, ana bazalt agrega oranı %80, 75, 70, 65 ile profillit ve zeolit oranları % 0, 5, 10 ve 15 olarak ayarlanmıştır. Katkısız beton (sadece %80 bazalt) ve 6 farklı reçete ile (bazalt+profillit ve bazalt+zeolit) beton üretilmiştir. 28 günlük kür bekleme sonucunda beton numuneleri üzerinde basınç dayanımı, eğilme dayanımı, ısıl iletkenlik ve kuru yığın yoğunluk deneyleri gerçekleştirilmiştir. Bu sonuçlara göre; %5’lik profillit ve zeolitin basınç ve eğilme dayanımlarının en yüksek seviyelerde olduğu saptanmıştır. %75 bazalt ve %5 zeolit oranında basınç dayanımı 27,65 MPa, eğilme dayanımı 5,45 MPa, ısıl iletkenlik değeri 1,21 W/m.K ve kuru yığın yoğunluk 2052 kg/m3 olarak saptanmıştır. %75 bazalt ve %5 profillit oranında basınç dayanımı 21,65 MPa, eğilme dayanımı 5,95 MPa, ısıl iletkenlik 1,21 W/m.K ve kuru yığın yoğunluk 2029 kg/m3 değerinde ölçülmüş ve malzemenin hafif beton üretiminde kullanılabileceği belirlenmiştir. Dayanıklı hafif beton eldesi için her iki malzeme (zeolit ve profillit)’nin aynı beton reçetesinde kullanılması önerilmektedir.

Comparative Study on the Effect of Cockle Shell Powder on Laterite Soil and Clayey Soil

Soil stabilization is physical or chemical process which improves the engineering properties of the soil and increase the stability of the soil. Main objective of this investigation has been focused on index and engineering properties of laterite soil and clayey soil reinforced with locally available cockle shell powder (CSP). The admixture CSP is added at a proportion of 12 to 20 % with an increment of 2 %. Reinforced earth technique is considered as an effective ground improvement method because of its cost effective and easy availability. Cockle shell powder is the most popular reinforcement materials used in the study on the soil reinforcement for expansive soil. Both the laterite and clayey soil will gain great strength with the addition of cockle shell powder. This improvement is due to an interaction between soils and the cockle shell powder which contain calcium oxide and calcium carbonate similar to chemical composition to cement additives. The effect of admixture on dry density, moisture content, plasticity, shear strength and UCS values of the laterite soil and clayey soil are determined in the laboratory. We can say it is a little bit of effective in using sea shells powder as admixtures when compared with other stabilizing agents.

Analisis Nilai Nilai Kadar Air Optimum Dan Kepadatan Kering Pada Tanah Lempung Dengan Penambahan Abu Cangkang Kemiri

The purpose of this study was to determine the effect of adding Candlenut Shell Ash to the maximum dry density and optimum moisture content in clay soil. Pecan shell ash as a clay soil density stabilization agent which was carried out by standard proctor testing. The research method used is Atterberg Limits testing, Moisture Content testing, Specific Gravity testing, Gradation testing (sieve analysis and hydrometer), and Compaction testing. From the characteristic tests it showed that the soil was classified as clay soil and the compaction test at point 1 and point 2 with mixed variations of 0%, 5%, 7%, 9% experienced an increase in the optimum water content. and maximum dry density. In the compaction test, 5 samples were carried out with the optimum moisture content value at point 1 of 0% variation, namely 22.855%, which continued to increase at the highest variation of 9%, namely 25.388 and at point 2, variation of 0%, namely 21.880%, continued to increase at variation of 9%, namely 24.217%, while the value of The maximum dry density at point 1 of 0% variation, which is 0.992, continues to increase at the highest variation of 9%, which is 1.058 and at point 2, variation of 0%, which is 0.957, also continues to increase at the highest variation of 9%, which is 1.047. From the results of the research conducted, it was found that Pecan Shell Ash increased the value of the optimum water content and the maximum dry density value so that it could be used to stabilize the soil.

Variability in the Solid Particle Density and Its Influence on the Corresponding Void Ratio and Dry Density: A Case Study Conducted on the MBT Reject Waste Stream from the MBT Plant in Marišćina, Croatia

In this study, a functional relationship between the solid particle density (ρs), void ratio e, and dry density (ρd) of mechanically and biologically treated (MBT) municipal solid waste (MSW) was examined. In total, 60 waste specimens were tested with an air pycnometer device and corresponding triplets (e, ρd,and ρs) of values were obtained. In addition, a long-term oedometer test with an allowed decomposition process was also conducted. Based on the obtained results, the variability in the solid particle density caused by heterogeneity and decomposition, as well as its influence on the corresponding void ratio and dry density values, were critically evaluated. The obtained results showed that the variability in the solid particle density caused by waste heterogeneity had a significant influence on the initial void ratio value. Furthermore, the obtained results also showed that the change in the solid particle density, caused by the degradation process, had a significant impact on the final void ratio and dry density values. In addition, an empirical relationship, ρd=fe, was proposed. The proposed function allows a landfill operator to establish the corresponding dry density at an arbitrary chosen void ratio, and vice versa, without having the exact knowledge of the corresponding solid particle density value.

Determine Field and Machine Operating Condition of Rice Combine Harvester to Minimize Grain Loss

Paddy can be harvested by a manual or mechanization metode. Mechanization harvesting also use some of machinery, one of example is rice combine harvester. This research has a goal to test performance of this machine in condition of field when the machine operates to know that it is worth or not to use based on national standard. The results of this research show that the field has a dry bulk density value 0.9 g/cc with 5.55 kgf/cm2 of cone index, water content is about 72.52 % and 65.49 % of soil’s porosity. Field efficiency of this machine is around 77.12 % with 915.28 kg/h of harvest capacity and 2.07 % of harvest losses. The capacity of hay disposal unit is about 170.4 kg/h with 97.69 % of grain cleanliness level. The slip that happened is about 8.01 % with actual velocity 0.535 m/s and 1.02 liter/h of fuel consumption. All of that are compared and evaluated with SNI 8185-2015 and the results show that this machine is worth to use in that area. Based on teority measurement on traction unit, this machine has rolling resistance around 121.6 kg from total weight, and has a critical traction around 532 kg and it has a rimpull value about 1525.15 kg.

Rock-Soil Transition In Weathering Of A Porphyritic Biotite Granite

Concentric layers of weathered materials around core-stones show the porphyritic biotite granite to experience sequential, but gradational, changes in visible features, textures and mineralogy as it transforms from ‘rock’ into ‘soil’. The changes start with the opening-up of grain boundaries and micro-cracks (stage 1) followed by their dark brown staining (stage 2) and the subsequent alteration (to sericite and clay minerals) of groundmass plagioclase feldspar grains (stage 3). Biotite flakes are then bleached and altered (to chlorite and clay minerals) (stage 4) before there starts alteration (to sericite and clay minerals) of groundmass alkali feldspar grains (stage 5) and finally alteration (to sericite and clay minerals) of the alkali feldspar phenocrysts (stage 6). Quartz grains are not altered during these stages of weathering, but disaggregate and reduce in size due to continual opening-up of grain boundaries and micro-cracks. Increasing stages of weathering are marked by decreasing dry unit weights, dry densities and uniaxial compressive strengths, but increasing apparent porosities. The transition between ‘rock’ and ‘soil’ occurs during stage 6 when all plagioclase, and most alkali feldspar, groundmass grains have been altered as are some alkali feldspar phenocrysts. Stage 6 is marked by large apparent porosities (>18%) but low values of dry unit weight (<20.81 kN/m3), dry density (<2,122 kg/m3) and uniaxial compressive strength (<1.8 MPa).

Engineering Assessment of the Soils of Modern Residential Complexes (Bety, Yarmouk, and Al-Jawhara) in Tikrit/Salah Al-din/Iraq

In this research, the geotechnical properties of soil for modern residential complexes in the city of Tikrit-Iraq were determined using six samples represented by three residential complexes (Bety, Yarmouk and Jawhara) and that these complexes built on gypsum soils suffer in the future from several engineering problems that appear in the form of cracks, inclination or subsidence in The buildings or the collapse of the facilities, the dilution of the roads and the breaking of the water and sewage networks due to the melting of the gypsum in the soil. One of the most important objectives for the research is that the residential complexes for the research area in Tikrit are not older than some years. With the urban expansion that all towns in Iraq are witnessing, including this region, the city of Tikrit represents the center of the province. Therefore most of the departments and institutions are present in this region, which necessitated the need to provide residential complexes and many of the constituencies' employees to occupy them in addition to its proximity to the University of Tikrit, so it is necessary to know the properties of soil, to point out the engineering problems in it and how to address them. As well, it is an important region from a geographical point of view because it is located directly on the main international road linking Baghdad - Tikrit – Mosul The moisture content values of the soil samples range from (0.92 to 0.26%). The resultant values ​​are low because one of the reasons is that the sampling process took place in the summer, specifically in July, and the reason is due to the low level of groundwater in the region, as well as the high temperature and the lack of rainfall, which causes the evaporation of the water in the soil, so the low moisture content gives a positive concerning the foundations of residential complexes in the study area because the presence of water causes the dissolution of gypsum as the soil under study contains a high percentage of gypsum. The calculated specific gravity values of soil samples range from 2.42 to 2.46 with an average of 2.42, The average specific gravity is 2.42 in the Bety and Yarmouk, and it is 2.46 in Aljawhara. The maximum dry density values of the soils of the residential complexes range between (1.611-1.663 gm/Cm 3( and the highest dry bulk density value was recorded in the sample (Y1). On the other hand, the optimum moisture content values range between 15.2% and 16.8%, while the highest value is for the sample )B2(. The consolidation test was performed on three selected samples (B2, J1, J2), ((A correction was made for the selection of samples to consolidation test based on the clay ratio, as was the case with the sieving analysis)) based on their clay content percentage compared to other samples which contain low or very clays, The compression index values (Cc) and the bulge index values (Cr) of these samples ​​are (0.084,0.114,0.092) and (0.012,0.013,0.009) respectively. The chemical analyses of the soil in the study area indicates that it contains a high percentage of gypsum that ranges between 43.05 and 69.27. % The gypsum content reaches the highest value in sample (B2) and lowest in sample J2. While the soluble salts percentage range from 73.13)to 85.21%), and the pH value ranges between 7.21and 7.67. Mineralogical, tests of indicate that most samples have prismatic gypsum crystals with several clinker substances, carbonate and evaporites cement and organic materials. The gypsum crystals range in size from 0.02 to 0.7mm with an amount of clay.

Fuzzy Random Prediction Model of Frost Heave Characteristics of Horizontal Frozen Metro Contact Channel in Coastal Area

The frost heave characteristics of artificial frozen soil are very important information for underground freezing engineering. It is found that both the frost heaving force and rate of the same soil layer increase with the decrease of freezing temperature. In addition, due to the comprehensive influence of freezing temperature, natural water content, dry density, and tidal flow peak value, the frost heave characteristics of different soil samples are evidently uncertain. With the aim of improving the deficiency of traditional BP neural network algorithms in solving fuzzy random engineering problems, random factor and mean square error between layers are used to modify the evaluation function of the network model. On this basis, taking tidal flow peak value, freezing temperature, natural water content, and dry density as inputs, the frost heaving force and rate of frozen soil as output values, and setting the number of hidden layer elements as 4, an improved fuzzy random BP network prediction model for frost heave characteristics was established. The new network prediction model has a smaller weight and bias, and the response tends to be smoother than the traditional one, which greatly reduces the overfitting phenomenon. The engineering example shows that the improved BP neural network prediction model can make the predicted value of frost heaving force and rate basically coincide with the measured value after effective training, and the error is controlled within 8%. Therefore, the prediction model can be used as an effective tool to predict frost heaving characteristics in Nantong metro freezing construction, and the corresponding model and method can also be extended to similar engineering cases.

DETERMINING THE SUITABILITY OF CLAY AT ITU, AKWA IBOM STATE, NIGERIA FOR ROAD CONSTRUCTION

Incessant road failures in Nigeria have become an issue of serious concern in recent times as a large portion of states and federal budgets are dedicated to revamping road infrastructures. In this study, we examined the geotechnical properties of clay samples collected from Ntak Inyang along Calabar-Itu highway, in Itu LGA of Akwa Ibom State, Nigeria with the aim of ascertaining whether the earth material at the study location is suitable for road construction. We carried out proctor’s compaction test, sieve analysis, California bearing ratio test and Attenberg’s limit test to analyse the clay samples for moisture content, California bearing ratio, plasticity and plastic limit, dry density and particle sizes. Results obtained indicate that the clay sample has an optimum moisture content of 13.53 %, dry density value in the range: 1580 kgm-3-1650 kgm-3, plastic limit of 22.15 %, plasticity index of 23 %, liquid limit of 45.63 %, sieve of 43.36 % with particles less than 0.075 mm and no particle size up to 5.0 mm, California bearing ratios of 9.0 % at 10.0 % moisture content, 6.7 % at 12.0 % moisture content, 2.0 % at 14.0 % moisture content. Based on these results, the clay sample is regarded as a sub-grade material with the classification of A-7-6 according to AASHTO (American Association of State Highway and Transportation Officials) classification. These results make the sample unsuitable for road construction but qualify it as a potential raw material for production of ceramic wares and tiles.

Geotechnical assessment and large scale direct shear testing on recycled brick aggregates

The current scenario of handling and recycling of construction and demolition (C&D) waste in India is not very promising. The proper management of C&D waste material is necessary to achieve sustainability goals in the field of Civil Engineering. In this research, the utility of recycled brick aggregates (RBA) in geotechnical applications is assessed by performing an extensive experimental program which includes tests like: particle size distribution, specific gravity, water absorption, modified proctor compaction, relative density, aggregate crushing, slake durability index, aggregate impact and Los Angeles abrasion. Shear strength parameters of RBA are evaluated by performing large scale direct shear test (DST). Source of origin of recycled brick aggregates (RBA) for the present study is MNIT campus, Jaipur. The RBA are found to have good compaction and shear strength characteristics as the values of maximum dry density (MDD), optimum moisture content (OMC), cohesion (c’) and angle of shearing resistance (Ф’), evaluated as 2.03 gm/cm3, 11.52 %, 55.82 kPa and 68° respectively. The large scale DST results are also compared with the available literature. The RBA are found to have susceptibility towards crushing failure, thus this study concludes that the RBA may provide good performance as a base/sub-base or backfill material only under the light loading conditions like: - footpath sub-base, light traffic loading road base and sub-base etc. It is recommended that the incorporation of geosynthetic reinforcements or some durable C&D waste aggregates in RBA may enhance its applicability as a sub-base material under heavy traffic pavements.

EFFECT OF COMPACTION AT DIFFERENT ENERGY LEVELS ON THE GEOTECHNICAL PROPERTIES OF STABILIZED SOILS

This study is aimed at evaluating the influence of compaction (at different energy levels) on the geotechnical properties of stabilized soils. To achieve this, four bulk soil samples (BDL1, BDL2 BDL3 & BDT) consisting of termite reworked soils and residual lateritic soils were collected at New Stadium Road, Awo hall, University of Ibadan, Nigeria at a depth of 2m for strength tests and at depths of 1m, 1.5m & 2m for index tests. Geotechnical analysis (index tests and strength tests) and geochemical analysis (X-ray Diffraction) were carried out on the sampled soils. The study revealed that the mineral constituents of the sampled soils are quartz, kaolinite and hematite; with the termite-reworked soil richer in kaolinite content than the quartz schist derived soil with about 125% increase. The values of index tests for both soils met the required Nigeria specification for good soil with termite reworked soil performing better. The values of specific gravity for both soils are close suggesting similar origin. AASHTO classification put termite-reworked soil within the range of A-2-7 (good rating) while most of the residual soil samples fall within A-7-5 to A-7-6 range (fair to poor rating). The stabilisation of residual lateritic soil using termite-reworked soil as stabiliser brought about increase in the values of maximum dry density, uncured unconfined compressive strength as well as the sun-cured unconfined compressive strength of the studied soil. The influence of stabilisation using termite-reworked soil was strongest at the highest level of compaction ((30%) of termite-reworked soil with the weight of residual soil). There also exist a fairly strong positive correlation between the amount of termite reworked soil and energy of compaction and between the uncured and sun-cured unconfined compressive strength was plotted against the number of blows for BDL1, BDL2 and BDL3 respectively. In sum, these stabilised soils are suitable for foundation and landfills materials.

Shear strength of fibre reinforced cemented Toyoura sand

<abstract> <p>A series of consolidated drained and undrained tests are conducted on unreinforced, fibre, cement, and fibre reinforced cemented Toyoura sand specimens with varying relative densities. Three different types of materials e.g., Toyoura sand, polyvinyl alcohol (PVA) fibres, and ordinary Portland cement (OPC) are employed in this study. Specimens in dimensions of 50 mm in diameter and height of 100 mm are prepared in a polyvinyl chloride (PVC) mold to a target dry density value, $ {\rho }_{d} $ = 1.40 g/cm<sup>3</sup> (Dr = 20%) and $ {\rho }_{d} $ = 1.489 g/cm<sup>3</sup> (Dr = 60%) of Toyoura sand using under-compaction moist tamping technique. Fibre reinforced cemented Toyoura sand samples were prepared with 10% moisture content by weight of sand-fibre-cement mixtures. The results on density variation shows that due to a better contact between sand-fibre interaction or sand-cement-fibre bonding and interaction for the denser specimens, a greater increase in shear strength is observed. However, the general effectiveness of fibre and cement additives alone and when mixed together also enhances the strength of unreinforced specimens for loose conditions based on the variation of fibre and cement contents. The results and findings in the current study can be used for the construction of economical and sustainable geotechnical infrastructures.</p> </abstract>

Pengaruh Abu Sekam Sebagai Subtistusi Semen terhadap Slump Flow dan Berat Isi pada Flowing Concrete

In a construction project, the presence of dense reinforcement between reinforcement has its own problems when casting, namely when compaction it is very difficult to use a vibrator because of the density between the reinforcement. To minimize the negative impact of this, flowing concrete is made so that without using a vibrator, the concrete will self-compact properly. The constituent materials of flowing concrete are aggregate, cement and water. In the process of making cement production will produce carbon dioxide in the air, resulting in air pollution due to cement manufacture. To minimize the impact of air pollution due to cement, in this study, we tried one of the constituents of flowing concrete, namely partially substituted cement, so as to minimize air pollution. In this study, rice husk ash, which is the residue from burning rice husks, was used as a partial substitution of cement. The method used is conducting research in the laboratory. In this study, the variation of husk ash as a cement substitution was 0%, 5%, 7.5%, 10% and 12.5% with the addition of 1.5% superplasticizer. From the results of the study, the smallest diameter of slump flow was 53.17 cm in a mixture of 10% rice husk ash. The largest dry concrete density value is 2482.77 kg/m3 at 10% rice husk ash mixture. The conclusion that can be drawn is that based on slump flow and dry concrete density, the optimal substitution percentage for rice husk ash is 10 percent.

CHARACTERIZATION OF ANATOMICAL, MORPHOLOGICAL, PHYSICAL AND CHEMICAL PROPERTIES OF KONAR (ZIZIPHUS SPINA-CHRISTI) WOOD

The goal of this research is to investigate some morphological (fibre length, fibre diameter, cell wall thickness, Runkel coefficient, flexibility coefficient, slenderness coefficient, rigidity coefficient, Luce's coefficient, solid coefficient), physical (dry wood density, volumetric shrinkage) and chemical (cellulose, hemicellulose, lignin, ash and acetone soluble extractives contents) composition of Konar (Ziziphus spina-christi) wood grown in Hormozgan province, Iran. For this purpose, three normal trees were selected randomly and a disk was cut from each one at breast height. Anatomical inspection revealed that the species was diffuse porous, with distinctive growth rings, simple preformation plate, with polygonal openings, and banded or diffuse-in aggregates parenchyma. The average values of wood dry density, fiber length, fiber diameter, cell wall thickness, Runkel coefficient, flexibility coefficient, felting coefficient, Luce’s coefficient, solid coefficient, rigidity coefficient were 0.926, 52.1, 77.85, 0.57, 163 ×103 μ3 and 0.48. Cellulose, hemicellulose, lignin, acetone soluble, extractives, ashcontents were43.34, 19.98, 33.9, 6.42 and 2.78%, resp.

Consolidated drained behaviour of PVA fibre reinforced cemented Toyoura Sand

ABSTRACT In this study, a series of consolidated drained (CID) compression tests were performed On unreinforced and reinforced cemented Toyoura sand specimens. Specimens were cured for 3, 7, 14, 28, 56 days, with cement contents of 0–3% (dry weight), and different Polyvinyl alcohol (PVA) fibre contents of 0, 0.5, 1, 2, and 3% (weight ratio). Samples were prepared to a target dry density value (e.g. = 1.489 g/cm3) of Toyoura sand using under-compaction moist tamping technique with 10% water content by dry weight of soil. Triaxial compression tests (CID) were carried out at a confining pressure of 100 kPa. The monotonic stress–strain, stiffness, volumetric change behaviour, dilatancy angle, peak strength, and residual strength and brittleness index of the samples were investigated in greater detail. Results show that peak strength increases due to increase in curing duration by approximately 50–700%, and 0–300% in residual strength at 30% axial strain, compared to Toyoura sand. For reinforced cemented specimens there is an increase in volumetric strain with increasing curing duration or in other words, the rate of dilation increases with the increase in curing period. The dilatancy behaviour increases due to the addition of fibres and cement, this dilative behaviour has been attributed to cemented particles forming highly interlocked clusters. Brittleness of the cemented specimens reinforced with 0.5%-1% fibres have been supressed significantly compared to the higher concentrations of fibre (2–3%). Hence, it shows that there might be a threshold fibre concentration range (0.5%-1%), where fibres are considered to be the most effective and beyond this concentration, fibre causes further adverse effects.

Improving the sub-base materials at Al-Fao port in Basrah Governorate-South of Iraq by adding some synthetic polymers and cement

The improvement process by adding polymers and cement has been carried out to sub-base material used in the compaction processes, in order to observe their effects on the geotechnical properties of the sub-base such as compaction, unconfined compressive strength, shear strength, California bearing ratio and absorption ratio. It has been observed that there is a significant improvement in the geotechnical properties of the soil as the value of the maximum dry density increased from 2.144 to 2.220 g/cm3, while the value of the optimum moisture contents decreased from 6.3 to 5.2% with a percentage of 5 % of the first polymer (Polyvinyl Acetate & Polyol). It is also revealed that there is an increase in the value of the unconfined compressive strength after adding 5% of the first polymer and 5% cement to the sub-base sample, and then soaked in water for different periods of time, the result was 11550 kPa with a soaking period of 28 days. Also, the angle of the internal friction values increased in testing the direct shear strength from 35◦ to 45◦ by adding 5% of the first polymer, and cohesion occurrence among the particles of the material under the action of the polymer as a adhesive material, the value reached 200 kN/m2. The California bearing ratio increased from 49% to 64% by adding 5% of the first polymer, while the absorption ratio decreased considerably at the same ratio and material from 9.8% to 4.1%.