Increase In Unit Weight Research Articles

Unit Weight and Elastic Modulus of Concrete utilizing Volcanic Stone Waste as Coarse Aggregate

Unit weight and elastic modulus of concrete utilizing volcanic stone waste (VSW) as coarse aggregate have been studied at 28 days of hydration. The origin of VSW was the residual of volcanic stone processing for making the handmade ornaments of traditional Balinese buildings. Three types of concrete mixture compositions were made by varying the proportion of cement, fine aggregate and coarse aggregate in concrete. Each mixture composition stirred using four variations of water/cement (w/c) ratio. For each variation in w/c, five cylindrical specimens with a diameter of 150 mm and a height of 300 mm were made to measure the unit weight and modulus of elasticity of concrete specimens after 28 days of hydration. The result shows that the unit weight and the elastic modulus of concrete decrease with increasing w/c at fixed proportions of cement and aggregates and increase with increasing proportion of aggregates at fixed w/c. The increase in elastic modulus with an increase in the a/c ratio for a fixed w/c ratio is more noticeable for a w/c ratio of more than 0.6. Moreover, the elastic modulus increases correspondingly with an increase in unit weight for a given a/c ratio.

Impact of Climate Change on the Stability of the Miacher Slope, Upper Hunza, Gilgit Baltistan, Pakistan

Especially in recent years, the study of landslide phenomena is considered as very important because of the effects of climate change. The aim of this paper is to examine the stability of the slope located in Miacher Nagar village along the Hunza River (HR), using the Limit Equilibrium Method (LEM). The Miacher slope rises to a height of 900 m from the foot of the Hunza River and has a base angle of 50 degrees. Meta-sediments and quaternary recent glaciated deposits make up the majority of the slope’s composition. The slope movement of Miacher was first triggered in 1995, and was further triggered in 2010 and 2013. The slope was geologically, geomorphologically, geotechnically and geochemically investigated as well as modeled by Slope/w to determine the safety factor. Soil samples were analyzed for their geotechnical, geological and geomorphological properties. The Limit Equilibrium Method (LEM) was employed in this study to analyze the Factor of Safety (FOS) of the slope, based on assumptions of the Morgenstern and Price, Ordinary, Janbu and Bishop Methods, using the Slope/w software. Various factors, including pore water pressure, unit weight, cohesion, angle of internal friction and overburden, were examined by analyzing different scenarios. The findings showed that an increase in cohesion and angle of internal friction resulted in an increase in FOS, whereas an increase in unit weight and overburden caused a decrease in FOS. The influence of pore water pressure was positive to a certain extent, but a further increase led to a significant reduction in FOS. The results showed that the Miacher slope is currently stable, as all FOS values were greater than one, based on the existing strength parameters and simulated results obtained using Slope/w.

Investigation on properties of cement mortar with bottom ash and perlite

AbstractPerlite and some recycled materials are preferably used to provide thermal insulation and lightness in mortar. Cement is often used as a binder in such a composite, although it makes the composite heavier and impairs its insulation properties. In this study, recycled bottom ash (BA) and expanded perlite (EP) as the aggregate, and cement as the binder and the optimum solution were investigated by using Taguchi Method. Depending on the specimens prepared using orthogonal array L9, the values of compressive strength, flexural strength, flowability, dry unit weight, water absorption, capillarity coefficient, and thermal conductivity coefficient were calculated. In general, it was found that the cement dosage was the most effective parameter and the thermal conductivity coefficient increased in parallel with the increase in unit weight and strength.

Flexibility analysis of inventory cost model with ergonomics

The economic and environmental sustainability issues in supply chain management have integrated by many researchers in the past decades. The ergonomics as a social aspect of sustainability had received a little attention by researchers. Therefore, the aim of the paper is analyzing the flexibility of developed inventory cost model with relaxation allowance and endurance time as a social aspect of sustainability. The effects of distance, unit weight of item and total number of items on relaxation allowance, the total cost of logistics operation and the EOQ model were investigated. The analyzed mathematical model was a single operator-single material model which covered transportation of fixed amount of raw materials from storage plant to production plant by manual material handling with simple cart and picking, storing, pushing and pushing back with empty cart for manual handling of the products. The different parameter values applied for analysis such as total amount of handled items (Q) changes between 500 pcs to 2750 pcs, unit weight of item (w) changes between 0.1 kg to 1 kg, distance of movement by manual material handling for picking and storing motions (d1) changes between 2 m to 3 m and the distance between the storing equipment and the supermarket of the production line for pushing motion (d2) changes between 15 m to 20 m. The results of the analysis indicated that the longer the distance of movement for all motions leads to decrease in savings of the model compared to EOQ model. The increase in unit weight of item is increase the savings obtained from application of our model and decrease the optimal lot size. There was no specific change on savings or optimal lot size as the total amount of handled item is increase. The compared results indicated that an increase in d1 and d2 lead to an increase in optimal lot size and increase in total cost of the model. Consequently, the analysis has shown that a decrease in lot size would be the better way to improve both ergonomic conditions and total cost of production in any different parameter values. Finally, the analysis of the inventory model with ergonomics were proved that this model is suitable for different industrial practices.

Roof collapse mechanisms for a shallow tunnel in two-layer rock strata incorporating the influence of groundwater

Abstract It is inevitable that adverse conditions such as layered strata, groundwater, and ground overload will be encountered during the excavation of shallow tunnels. However, analytical theories on shallow tunnel stability are not well investigated while taking above factors into consideration together. In this paper, a shallow tunnel in two-layer rock strata is taken as an example. The influences of the groundwater table, ground overload, supporting force, etc., are considered. The corresponding kinematically admissible velocity fields for roof collapse under two cases are established. The analytical solutions of the curvilinear equations for failure of the roof surrounding rock masses and the critical burial depth of the shallow tunnel in Case I and Case II are obtained, respectively, based on upper bound theorem and variational principle. In addition, the influencing regularities of the roof collapse mechanisms under differing mechanical parameters are analyzed. It was found that the roof collapse range increases when the groundwater table drops or the supporting force, rock empirical parameter A, compressive strength, or tensile strength increase. Conversely, the roof collapse range decreases when the thickness of the upper stratum, pore water pressure coefficient, ground overload, rock empirical parameter B, or unit weight increase. The collapse range indicates the safety state of the tunnel roof. The larger the range is, the more external force power is required to generate collapse and the safer the roof is. Practically, it is efficient to improve the roof stability of the shallow tunnel by increasing the supporting force or employing the grouting technique to increase rock empirical parameter A and other strength parameters.

Measurement of Unit Weight of Dry Sand Using Piezoelectric Sensor

Recently, an electro-mechanical impedance (EMI) technique has found wide application in the monitoring of concrete structures. This EMI technique was employed for measuring the unit weights of various grain sizes of sand and the relevant process is reported herein. A piezoelectric sensor (PZT, i.e., lead zirconate titanate sensor) was imbedded into small, medium, and large-sized grains of the Nakdong river sand and a surcharge was applied. The effect of an increase in unit weight owing to the surcharge was investigated in terms of the resonant frequency (peak frequency) and corresponding conductance at resonant frequency (peak conductance). A ceramic-coated PZT sensor was used to prevent the occurrence of a short circuit. The measured peak frequency and conductance from the PZT sensor were correlated with the unit weight of sand. With an increase in the unit weight of sand, the peak PZT frequency was found to have increased, however, the peak conductance was seen to have decreased. The peak PZT frequency and conductance were seen to be strongly correlated with the unit weight of Nakdong river sand except for the peak conductance of large grain sized sand.

Roof failure of shallow tunnel based on simplified stochastic medium theory

The failure mechanism of tunnel roof is investigated with upper bound theorem of limit analysis. The stochastic settlement and nonlinear failure criterion are considered in the present analysis. For the collapse of tunnel roof, the surface settlement is estimated by the simplified stochastic medium theory. The failure curve expressions of collapse blocks in homogeneous and in layered soils are derived, and the effects of material parameters on the potential range of failure mechanisms are discussed. The results show that the material parameters of initial cohesion, nonlinear coefficient and unit weight have significant influences on the potential range of collapse block in homogeneous media. The proportion of collapse block increases as the initial cohesion increases, while decreases as the nonlinear coefficient and the unit weight increase. The ground surface settlement increases with the tunnel radius increasing, while the possible collapse proportion decreases with increase of the tunnel radius. In layered stratum, the study is investigated to analyze the effects of material parameters of different layered media on the proportion of possible collapse block.

Evaluation of physical and mechanical characteristics of siderite concrete to be used as heavy-weight concrete

The objective of this study is to investigate the usability of siderite aggregates mentioned above as a heavy-weight aggregate in the heavy-weight concrete production and their effects on physical properties of the heavy-weight concrete mixture. For this purpose, normal-weight aggregate content was decreased at the rate of 20%, 40%, 60%, 80% and 100% by volume of the concrete mixture prepared and mixtures were prepared by its substitution with siderite aggregate at the same rates. Based on the increase in siderite aggregate in the concrete mixture, a considerable increase in unit weight, compressive strength and tensile strength of concrete was obtained. Plate-shaped concrete specimens obtained from combined normal-weight and heavy-weight aggregates were exposed to radiation with different X-ray source (118 keV, 164 keV) and Co-60 (1250 keV) beam source at Çekmece Nuclear Facility. It is clearly seen that the concrete mixture containing siderite aggregate improved 70% radiation absorption characteristics compared to that of the concrete mixture without siderite aggregate.

Strength tests of enzyme-treated illite and black soil mixtures

Enzymes are organic degradable materials, recently introduced as soil improvement additives for earthen pavement layers and embankments. This study was conducted to evaluate the effect of three enzymes on the unit weight and unconfined compressive strength of illite mixed with black soil. The optimum moisture content (OMC) and maximum dry density of the untreated soil were determined with a standard Proctor test. The same test was conducted to prepare untreated and treated soil samples at OMC. Samples were prepared for two dosages and two curing periods. However, no considerable increase in unit weight was observed for specimens treated with the three enzymes. Larger-sized soil samples were prepared to reduce the inaccuracy in sample preparation and testing. No noticeable improvement was observed for any of the enzymes and dosages. Some of the samples showed a little increase in strength but that was found to be due to the higher densities of those samples. A Fourier transform infrared spectroscopy test was executed to investigate the structure and functional groups of the three enzymes and their effect on soil. Thermogravimetric analysis, differential thermal analysis and X-ray diffraction tests were performed to determine whether any chemical reaction took place between the soil and the enzymes, but no chemical reactions were observed.

Shear strength characteristics of mechanically biologically treated municipal solid waste (MBT-MSW) from Bangalore

Strength and stiffness properties of municipal solid waste (MSW) are important in landfill design. This paper presents the results of comprehensive testing of shear strength properties of mechanically biologically treated municipal solid waste (MBT-MSW) in laboratory. Changes in shear strength of MSW as a function of unit weight and particle size were investigated by performing laboratory studies on the MSW collected from Mavallipura landfill site in Bangalore. Direct shear tests, small scale and large scale consolidated undrained and drained triaxial tests were conducted on reconstituted compost reject MSW samples. The triaxial test results showed that the MSW samples exhibited a strain-hardening behaviour and the strength of MSW increased with increase in unit weight. Consolidated drained tests showed that the mobilized shear strength of the MSW increased by 40% for a unit weight increase from 7.3kN/m3 to 10.3kN/m3 at 20% strain levels. The mobilized cohesion and friction angle ranged from 5 to 9kPa and 8° to 33° corresponding to a strain level of 20%. The consolidated undrained tests exhibited reduced friction angle values compared to the consolidated drained tests. The friction angle increased with increase in the unit weight from 8° to 55° in the consolidated undrained tests. Minor variations were found in the cohesion values. Relationships for strength and stiffness of MSW in terms of strength and stiffness ratios are developed and discussed. The stiffness ratio and the strength ratio of MSW were found to be 10 and 0.43.

COMPOSITE MIXTURE OF STONE DUST AND FLY ASH AS A SUBGRADE IN RURAL ROADS

Fly ash is an industrial waste produced by the burning of coal in thermal power plants. From past years, fly ash is disposed in the form of landfills. Fly ash is an engineering material with unique properties. When compared with typical soils used for embankment construction, fly ash has large uniformity coefficient consisting of silt-sized particles mostly. Addition of Stone dust modifies the gradation of fly ash and also there will be an increase in unit weight of the composite material. This study has been carried out to know the possibility of using fly ash in combination with stone dust and lime or cement. The engineering properties of composite material (fly ash-stone dust-lime\cement) have been studied to bring out the possibility of using fly ash in the construction of embankments. Addition of stone dust to fly ash results in an increase in Maximum Dry Density (MDD), and at the same time observed a decrease in Optimum Moisture Content (OMC). Due to addition of stone dust, a significant increase in California Bearing Ratio (CBR) value is observed. The composite material consists of 60% fly ash +40% of stone dust and 40% of fly ash + 60% of stone dust were further tested by adding lime. With addition of lime, there is a decrease in MDD and increase in the CBR value. The composite consisting of 40% fly ash + 60% stone dust with 2% lime resulted in a soaked CBR value of 9.0 at Maximum Dry Density (MDD) of 1.55 g/cm3. This composite material may be used for the construction of subgrade for rural roads.

Study on Incipient Motion of Consolidated Cohesive Fine Sediment

The incipient motion mechanism of cohesive fine sediment is different to the one of non-cohesive sediment. It is related to the consolidation while being influenced by the dry unit weight and particle size. By means of the rectangle piping flume, the influence mechanism of dry unit weight and particle size to critical shear stress of cohesive fine sediment is studied. Experimental results show that on the condition of consolidation, the influence of dry unit weight to incipient motion is divided into two different stages, one is that when dry unit weight increase quickly, but the influence to incipient motion is not greatly, another is that when dry unit weight increase slowly, but the influence to incipient motion is very greatly, the critical dry unit weight to two stages decline as mean particle size decrease. So the mean particle size is finer, the degree of dry unit weight influence to critical shear stress is stronger, and the incipient motion is more difficult when consolidation last longer; it is also shown consolidation is more disadvantageous to incipient motion.

Effect of different pre-sowing tillage on quantity and quality of parsnip (Pastinaca sativa L.) root yield in ridge cultivation

Parsnip is a very valuable vegetable due to its nutritional value and dietetic quality. It is moreover herbal raw material abundant in active substances. The yield quality of vegetables greatly depends on thorough pre-sowing soil tillage. The present study aimed at evaluating the influence of different presowing soil tillage (medium-deep ploughing, cultivating) and plant growing methods, flat or ridge cultivation, on the yield of parsnip and some biometric traits of its roots. The field experiment was carried out in 1999, 2000 and 2002 on lessive soil with the granulometric composition corresponding to medium silty loam. The parsnip cultivar 'Półdługi Biały' was the experimental plant species. The cultivation of parsnip on ridges had a significant influence on increased total yield of roots and decreased yield of small roots, as compared to flat cultivation. A significant increase in unit weight of the root and its diameter in the top part was also recorded in the latter type of cultivation. Spring pre-sowing tillage had no significant effect on parsnip yields. An increasing trend was observed only for total and marketable root yield in the ploughed plots. When parsnip is grown on lessive soil (which has an unstable structure), plants cultivated on ridges after spring pre-sowing plough are the most beneficial treatment combination.

Influence of melted incinerator ash on durability and corrosion behaviour of reinforced concrete

This study investigates the effects of incinerator bottom ash (IBA) fineness and the cooling process of molten IBA on the durability of concrete and the corrosion of rebar. Two finenesses of an original IBA, i.e. pulverized incinerator bottom ash (PIBA) powder with maximum particle sizes of 0.6 and 0.074 mm, were used to partially replace Portland cement at 20 per cent by weight. In addition, the powder was also obtained by melting the PIBA (<0.6 mm) in an electric-furnace at 1450 °C for 1 h and chilling it by quenching in water (WIBA, water-cooled melted incinerator bottom ash) and air (AIBA, air-cooled melted incinerator bottom ash). The powder was then ground in a ball mill until the particle size reached less than 0.074 mm. This study also presents the experimental results on the compressive strength, mercury intrusion porosimetry, scanning electron microscopy (SEM), and X-ray diffraction of concrete samples containing different types of IBA. This study uses the initial surface absorption test and rapid chloride penetration test to measure the absorption and the ability of different concrete samples to resist chloride ions. Cylindrical specimens were cast and exposed to 3.5 per cent NaCl solution under a direct current density (0.5 m A/cm2) to accelerate the corrosion process. The open circuit potential and direct current polarization resistance were obtained to evaluate the rebar corrosion. Results indicate that WIBA concrete achieved a compressive strength similar to reference specimens after 28 days of curing; WIBA and AIBA exhibited an increase in unit weight and workability when used as a replacement for cement. However, IBA can be processed by melting to regain reactive pozzolanic activity, which may be used to partially replace cement. The incorporation of WIBA and AIBA decreased the total capillary pore porosity of the mortars compared to ordinary PIBA. The large particle size of PIBA produced lower hydraulic properties than finer particles. The improved properties of WIBA and AIBA resulted from the dense structure achieved by the filling effect of the pozzolanic product. Strength activity index results, SEM, X-ray analysis, and the rate of ISA observations confirm these findings. Utilizing a proper amount of WIBA and AIBA significantly improved the chloride and corrosion resistance of rebar in concrete in this study. Therefore, WIBA and AIBA can act as cementitious materials in cement-based composites.

Influences of nonassociated flow rules on seismic bearing capacity factors of strip footing on soil slope by energy dissipation method

Seismic bearing capacity factors of a strip footing placed on soil slope were determined with both associated and nonassociated flow rules. Quasi-static representation of earthquake effects using a seismic coefficient concept was adopted for seismic bearing capacity calculations. A multi-wedge translational failure mechanism was used to obtain the seismic bearing capacity factors for different seismic coefficients and various inclined angles. Employing the associated flow rule, numerical results were compared with the published solutions. For bearing capacity factors related to cohesion and equivalent surcharge load, the maximum difference approximates 0.1%. However, the difference of bearing capacity factor related to unit weight is larger. With the two flow rules, the seismic bearing capacity factors were presented in the form of design charts for practical use. The results show that seismic bearing capacity factors related to the cohesion, the equivalent surcharge load and the unit weight increase greatly as the dilatancy angle increases, and that the nonassociated flow rule has important influences on the seismic bearing capacity.

Pore water pressure and streambank stability: results from a monitoring site on the Sieve River, Italy

To investigate the role of pore water pressures in the stability of a streambank, a series of tensiometers and piezometers was installed in a bank of the Sieve River, Tuscany, Italy. Fluvial entrainment at the bank toe was monitored by repeated cross-profiling, erosion pins and marked pebbles. Fluctuations in matric suction measured at the tensiometers reflected the overall response of pore water pressures to rainfall, evapotranspiration, rising and drawdown of the river stage, and variations in water table. An expression was derived for the safety factor with respect to mass movement of the upper bank, incorporating the failure criterion for unsaturated soils and the normal Mohr–Coulomb criterion for saturated conditions. Variations in matric suction have important effects on the stability of the streambank. During low-flow periods, the shear strength term due to the matric suction allows the bank to remain stable at a steep angle. However, during rainfall and flow events, reduction in matric suction and increase in unit weight of the material from vertical and lateral infiltration may be sufficient to trigger a mass failure, without development of significant positive pore water pressures. During the rising limb of high-flow events, the factor of safety increases as a consequence of the stabilizing confining pressure of the water in the river, despite a reduction in matric suction. During drawdown in the river, when the suction values are still low and the confining pressure in the river decreases to zero, the factor of safety falls to lower values than those experienced prior to the runoff event. Measurements of fluvial entrainment reveal that, although the processes, mechanisms and the frequency of retreat of basal and upper bank zones differ significantly, the amount of retreat at the bank toe due to fluvial erosion is comparable to that of the upper portion of the bank due to mass failure. Copyright © 1999 John Wiley & Sons, Ltd.

Effect of Condition of Animal on the Requirements of Energy for Maintenance of the Bovine1,2

Summary Three sets of monozygous bovine animals (two sets of triplet bulls and one set of twin steers) were used to study the relationship between the feed energy required to maintain body weight and the condition (fatness) of the animal. The animals within each set were fed rations with different contents of energy but which were not limiting in their supply of other nutrients. The rations fed caused certain animals of each set to weigh more and be in higher condition than others in the set. Under these circumstances, the TDN required per unit weight for maintenance increased materially as weight and condition increased. Under the circumstance, where the animals of a set were at the same weight but differed in condition, the animal that was fattest required the most TDN per unit weight for maintenance. The effect of feeding 15 g. thyroprotein to one bull in a set of triplets caused maintenance requirements per unit weight for TDN to be greater than for the bull of the set maintained in very high condition. It was concluded that maintenance requirements for energy per unit weight increase as condition of the animal increases or as effective quantities of thyroprotein are included in the ration of the bovine animal.