Moisture Density Research Articles

Study on performance of lightweight concrete bricks with a ratio of sand and cement composition

Cellular Lightweight Concrete (CLC) brick is a material composition for wall building made of Portland cement, water, and fine aggregate blended with a foaming agent. The weight of the brick is light due to the air cavities formed in the CLC brick. The number composition of sand and cement in the CLC brick could improve the strength of the bricks. Thus, it is essential to find out the sand and cement consumption in order to improve the rate of brick strength. The study aims to improve the strength of the CLC bricks with the different composition of the material and to find out the index properties of the CLC bricks with the variable component of the materials. The study used an experimental work in the material laboratory with two variations of the material composition. The first variation is mixing concrete for the ratio of cement and sand of 1:2, while the second variation is mixing concrete for cement and sand ratio of 2:3. The wet density of the CLC brick is about 800-900kg/m3, and the average compressive strength test was conducted at ages 3, 7, 14, and 28 days for each test. Three identical specimens were prepared for each test. The study resulted in the 28-day strength of the CLC brick with a mass ratio of cement to sand 1:2 of 0.52 MPa, and the strength of the CLC brick with a mass ratio of cement to sand 2:3 was 0.68 MPa. The first variation was lower by 24.5% than the second variation in terms of strength. The higher cement consumption used into the mixed can make porosity of the specimen decrease, and then the strength of the specimen will improve.

Evaluation of the Physical and Mechanical Properties of Autoclaved and Foamed Concrete Blocks Marketed in Passo Fundo/RS Brazil

Os blocos de concreto celular cada vez mais vêm ganhando mercado devido as suas características de isolamento térmico, de isolamento acústico, de baixa densidade, entre outras. Uma propriedade relevante é a resistência à compressão, a qual limita algumas aplicações deste tipo de material, por exemplo, a utilização em paredes estruturais (paredes que venham a ser submetidas a deformações impostas ou a cargas de ocupação mais significativas), as quais exigem uma resistência à compressão mínima de 3 MPa. Devido ao aumento da utilização do concreto celular nas construções, este trabalho teve como objetivo a avaliação das propriedades físicas e mecânica de dois tipos de blocos celulares comercializados na região de Passo Fundo/RS, Brasil. Ensaios experimentais foram realizados para determinar as seguintes propriedades: densidade seca, a densidade saturada, os índices de vazios, a absorção de água, a condutividade térmica e a resistência à compressão foram realizados. Os resultados mostraram que o concreto celular autoclavado apresentou melhores propriedades físicas e mecânicas quando comparado com o concreto celular espumígeno, isto é, o bloco de concreto celular autoclavado teve maior resistência à compressão, menor condutividade térmica, menor densidade e poros distribuídos de forma mais homogênea, porém os valores encontrados para a resistência à compressão de ambos os blocos foram inferiores aos determinados pelos fabricantes destes blocos. Portanto, os blocos de concreto autoclavado podem ser utilizados para alvenaria de vedação nas construções, pois atingiu a resistência à compressão mínima necessária para este tipo de parede. Já os blocos de concreto celular espumígenos, em média, apresentaram valores de resistência à compressão muito abaixo (0,6 MPa) dos valores exigidos para paredes de alvenaria de vedação (1,5 MPa), exigindo que o fabricante revise a formulação dos traços desses blocos.

The Influence of Kaolinite - Illite toward mechanical properties of Claystone

Abstract This study investigates the relationship between clay minerals (kaolinite and illite) and rock properties of the claystone, including both mechanical (cohesion, friction angle, stress, and strain) and physical properties (natural water content, void ratio, and wet density), belonging to Warukin Formation of Kalimantan, Indonesia. Mineralogical characteristics of these rocks were studied using petrological and X-ray diffraction techniques, whereas the mechanical and physical properties were tested by conducting uniaxial and triaxial tests. Relationship among the variables was determined using correlation coefficients. It was observed that the mineralogy of the rocks pose strong constraints on their engineering properties. The results showed that an increase in illite content decreases cohesion, friction angle, strength, and safety factor; and increases natural moisture content, void ratio, and wet density. Although illite content of these rocks was just about 10.8% of the total minerals, it has significantly contributed to the modification of physical and mechanical properties. In contrast, kaolinite did not have a significant impact; since the correlation between various parameters was significantly low (correlation coefficient was much less, <0.3). Therefore while selecting the materials for geotechnical engineering applications, illite emerges as a safer alternative to kaolinite, especially when its concentration is less than 10.8% of the total rock mass.

Control system for a continuous compaction large square baler

Bale density impacts the cost to harvest, aggregate, store and transport hay or biomass. To achieve legal transport weight limits in many countries, the large square bale (LSBe) wet basis density should be approximately 240 kg·m−3. Current large-square balers (LSBers) create density by employing a reciprocating plunger to apply pressures in excess of 700 kPa to the bale face, but densification by a reciprocating plunger is inefficient because of the intermittent manner that the pressure is applied. What is explored here is an alternative bale densification method that uses an auger and conical compaction rollers to compact material in a continuous fashion. Compared to conventional LSBers, this new baler concept has the potential to create high-density bales with a machine that is less complicated and lighter weight. An important component of this baling mechanism was a closed-loop control system developed to achieve a desired bale density, as well as control bale separation and bale length. The control system varied bale chamber compression panel pressure to alter auger force and subsequent bale density. Using this control system enabled the baler to achieve dry basis densities ranging from 166 to 334 kg·m−3 with auger forces less than 44 kN, nearly a fifteen-fold reduction in force compared to a conventional plunger type LSBer.

Lime Treatment of Coal Bottom Ash for Use in Road Pavements: Application to El Jadida Zone in Morocco.

Featured Application In this paper waste bottom ash from a thermal power station was treated with lime and sand. This improves certain material characteristics leading to a potential use in a subbase in road construction. Industrial waste causes environmental, economic, and social problems. In Morocco, the Jorf Lasfar Thermal Power Station produces two types of coal ash with enormous quantities: fly ash (FA) and Bottom ash (BA). FA is recovered in cement while BA is stored in landfills. To reduce the effects of BA disposal in landfills, several experimental studies have tested the possibility of their recovery in the road construction, especially as a subbase. In the first phase of this study, the BA underwent a physicochemical and geotechnical characterization. The results obtained show that the BA should be treated to improve its mechanical properties. The most commonly used materials are lime and cement. In the selected low-cost treatment, which is the subject of the second phase of the study, lime is used to improve the low pozzolanicity of BA while calcarenite sand is used to increase the compactness. Several mixtures containing BA, lime, and calcarenite sand were prepared. Each of these mixtures was compacted in modified Proctor molds and then subjected to a series of tests to study the following characteristics: compressive strength, dry and wet California Bearing Ratio (CBR), dry density and swelling. The composition of each mixture was based on an experimental design approach. The results show that the values of the compressive strength, the dry density, and the CBR index have increased after treatment, potentially leading to a valorization of the treated BA for use in a subbase.

Investigating the Properties of Foamed Mixture Lightweight Soil Mixed with Bauxite Tailings as Filler

To make better use of large amounts of discarded bauxite tailings (BTs), a foamed mixture lightweight soil mixed with BTs as filler (FMLSB) was proposed. Using the orthogonal experimental design method, the effects of various contents of cement, BTs, and foam on the fluidity, wet density, unconfined compressive strength, water absorption, and microstructure of FMLSB were studied. The experimental results indicate that the wet density and unconfined compressive strength increase as the contents of cement and BTs increase but decrease as the foam content increases. Water absorption increases with the reduction of the wet density, but the unconfined compressive strength exponentially increases as the wet density increases. With an increase in the contents of cement and BTs and a decrease in the foam content, fewer pores are present, and the pores are not connected with each other. The results of the range analysis show that the main factor affecting the wet density and unconfined compressive strength of the FMLSB is the foam content, followed by the cement content, and meanwhile, BTs can maintain the lightweight and high strength of FMLSB. Based on the intended engineering applications and standard specifications, the optimum composition of the FMLSB mixture is proposed. Overall, the results indicate that BTs have the potential to be used as filler to produce FMLSB and that applications of FMLSB will lead to great economic and environmental benefits in engineering construction.

Sound Velocity Predictive Model Based on Physical Properties

AbstractThe correlation between sediment sound velocity (V) and physical properties has been studied for 60 years using empirical equations, and it has been found difficult to predict V accurately. Random Forest (RF) is a scientific discipline and a method of data analysis that automates analytical model building. Here we present the implementation of RF algorithm in V prediction and sediment classification. The databases were from previously collected data in the northern South China Sea. The goal of this study is to establish a predictive model based on RF using multiple physical properties (mean grain size, porosity, wet bulk density, and water content). Compared to empirical equations, the average error of RF velocity is only 0.95%, ranging from 0.03 to 2.73%, indicating that the RF algorithm has improved the accuracy of V prediction. We also used mean decrease impurity importance to evaluate the importance of a variable and found that the most important feature in the predictive model is mean grain size. We also used the RF as a potentially useful tool for sediment classification. The classification model has up to 75% accuracy in the dataset. Multiple features, such as physical properties, sedimentary environment, and sediment source, affect the geoacoustic properties of sediments. The next goal is to use multiple features to improve the model and further improve the accuracy of sound velocity prediction and sediment classification.

Construction Techniques and Quality Test and Evaluation of Lightweight Cellular Concrete Mixed with Fly Ash as Subgrade Material

To improve the comprehension and utilization of lightweight cellular concrete mixed with fly ash (LCCF) and ensure project quality in subgrade construction engineering, the construction techniques and quality control measures of LCCF are studied in this paper. The corresponding research contents, based on a specific project case located in Guangdong Province, are as follows. Firstly, the construction technology process and technological measures are put forward, according to the site construction conditions and quality requirements. Secondly, the feasibility of indoor mixture ratio is further verified by measuring the fluidity, wet density, and strength on-site. Thirdly, the suitable pouring thickness of the single layer and reasonable interval time between layers are determined by the vertical delamination test and surface strength test. In this paper, the indoor mixture ratio of LCCF has been improved through tests such as single factor test and multifactor orthogonal test considering factors like fly ash, water-binder ratio, and foam. Some highlights of this article are as follows: the preparation methods of lightweight concrete in laboratory and in situ are given. And two patented test devices are used for the strength test along with the depth and surface strength test, respectively. Besides, the practical engineering case is Lianjing Bridge, of which mileage pile number is K80 + 679.679∼K80 + 760.113, which is part of a highway in Zhaoqing City, Guangdong Province, China.

Laboratory simulation of gravel-type sediment environments with different wet density by means of sediment hardness

Laboratory simulation of gravel-type sediment environments with different wet density by means of sediment hardness

Fishery-independent observations of Atlantic menhaden abundance in the coastal waters south of New York

Atlantic menhaden (Brevoortia tyrannus) is a migratory forage fish whose geographic range extends from the Gulf of Maine to Florida. Despite the ecological and commercial importance of menhaden, few fishery-independent surveys have been conducted to quantify their distributions of abundance and biomass. Active acoustic surveys of menhaden schools were conducted using 38, 120, and 200 kHz scientific echosounders in two regions on the continental shelf south of Long Island, New York during the summer of 2014 and spring, summer, and fall of 2015. Spatial distributions of menhaden schools were considered to be clustered across all surveys where three or more schools were observed. Estimates of school volume were highly variable, ranging from 30 to 48,000 m3. Menhaden aggregations were absent in the spring (April, May, and June) and present in the summer and fall (July, August, and September) surveys. Target strength measurements at 120 kHz during the summer and fall surveys were consistent with predicted values for adult Atlantic menhaden, suggesting that fish size did not change substantially during this time. Peak menhaden abundance was observed during August 2015 (approximately 157,000 fish km−2 with a wet weight biomass density of 35,000 kg km−2). Multifrequency acoustic surveys can provide an efficient and fishery-independent method for quantifying menhaden abundance and distribution in coastal habitats.

Advanced soft computing techniques for predicting soil compression coefficient in engineering project: a comparative study

Heterogeneous nature of soil consists of various chemical and physical attributes that make the prediction of soil parameters very tedious and challenging. Moreover, it becomes more difficult when we have more number of variables. This study investigates the feasibility of principal component analysis as dimensionality reduction technique to select the input variables in terms of principal components (PCs), which helps in reducing the complexity and multicollinearity problem. The soil attributes, namely depth of the sample, sand percentage, silt percentage, clay percentage, moisture content, dry density, wet density, void ratio, liquid limit, plastic limit, liquid index, and plastic index, have been employed as influencing factors to estimate the coefficient of compression of soil. Furthermore, the extracted variance-based PCs were used as predictor to build the minimax probability machine regression (MPMR), multivariate adaptive regression splines (MARS), and genetic programming regression (GPR). The predictive accuracy of the models has been assessed via five statistical fitness parameters. In the training phase, the PCA-MARS model has shown good outcomes in terms of fitness measurement parameters (RMSE= 0.004, r = 0.981 and NSE = 0.963). During testing phase, PCA-MARS has outperformed (RMSE= 0.006, r = 0.963 and NSE = 0.912) followed by PCA-GPR and PCA-MPMR. The finding of this research concludes that PCA-based MARS model can be used as new and reliable data-driven approach for estimation of soil parameters. Furthermore, this new tool can help to save the time and capital spent on estimation of different parameter of soil.

Sediment classification in a Brazilian reservoir: Pros and cons of parametric low frequencies

Sediment is the main factor that limits the reservoir lifetime. Therefore, sediment classification is an essential tool for planning and operating reservoir management measures. There has been important development in the hydroacoustic classification of lakebed, especially with linear systems. The main restrictions while using linear hydroacoustic systems for lakebed classification are the shallow penetration in high-frequency applications or the low vertical and horizontal resolution when using low frequencies. With the new developments in the area of echo sounders, parametric systems can achieve high penetration while preserving the high vertical and lateral resolution. To investigate the performance of parametric systems, a new lakebed classification approach was implemented by using a SES2000 Compact. The area studied was the Passauna reservoir in Parana State, Brazil. We used the first echo division method for processing the acoustic data combined with sediment core and grab sampling. The two physical parameters investigated, were the share of the finest fraction (<63 µm) and wet bulk density (WBD). The results showed a high correlation between the primary frequency of 100 kHz (166 µs pulse length) and the physical parameters. Additionally, a significant correlation was observed with the acoustic parameters at 10 kHz frequency. The best correlating acoustic parameter was Attack/Decay (E1´/E1). The gas presence was found to be an important factor determining the penetration depth of the parametric system and the performance of the classification. The advantages of parametric systems, such small directivity and layering effect, represent the major restrictions in sediment classification applications.

Effect of paste volume on fresh and hardened properties of concrete

Water to cement (W/C) ratio has been deemed as one of the most important factors affecting the properties of concrete. However, at constant W/C ratio, cement or cementitious paste volume (CPV) also plays an important role, yet limited research has been done to quantify and unveil the mechanism behind. In this study, the effect of CPV on various performance attributes of concrete at fresh and hardened states was evaluated by varying the CPV from 26% to 32% at two different W/C ratios. Based on the tests results and inter-relationships among them, it was found that decreasing the CPV, i.e., reducing the cement content at constant W/C ratio, would decrease the uncompacted wet density while increase the compacted wet density, increase the strength at all curing ages, increase the Young’s modulus, flexural strength and splitting tensile strength, and improve the quality of concrete, albeit the decrease of workability that could be compensated by increasing the superplasticizer dosage or adding fillers. Moreover, mechanisms behind these phenomena have also been revealed from the perspective of mortar film thickness. The work presented herein should be meaningful in the development of eco-friendly high performance concrete.

Population status and habitat preference of Soemmerring’s gazelle in Alledeghi Wildlife Reserve, Eastern Ethiopia

AbstractThis study was undertaken to determine the current population size, structure and habitat preference of Soemmerring's gazelle [Nanger soemmerringii (Cretzschmar 1828)] in the Alledeghi Wildlife Reserve, NE Ethiopia. Animals were counted, both during dry and wet seasons, along 12 line transects each in three habitat types (grassland, tree‐scattered grassland and bushland) in 2015/16. Habitat type had nonsignificant effect on mean population density of Soemmerring's gazelle, but wet season mean density was significantly higher than dry season mean density. Estimated weighted mean (±95% CI) population density of the species in the reserve was 1.90 (±0.17) and 5.99 (±0.370) individuals/km2 during the dry and wet seasons, respectively. Total population size of the species in the Alledeghi Wildlife Reserve was estimated at 826 ± 77 and 2,562 ± 158 individuals during the dry and wet seasons, respectively. Over half of the total population of Soemmerring's gazelle was represented by adult females during both seasons. Seasonal habitat preference of Soemmerring's gazelle was statistically significant, with greater preference for grassland habitat during wet season and for bushland habitat during dry season. In conclusion, this study has provided valuable data that will be used as a baseline for future population monitoring.

A Study on Suitability of Foamed Sandcrete Solid Block with Fly-Ash as Partial Replacement of Sand

In this study, the properties of foamed sandcrete solid block (FSSB) with varying percentage of sand replacement with fly-ash were investigated. These properties include workability, wet and dry density, stability, water absorption capacity and compressive strength. 150mm cube specimens were used for the determination of both the compressive strength and the dry density of the FSSB. The plastic density was investigated using a container of known volume, and its workability determined using the slump test. The fly-ash content was varied from 0 to 50% at interval of 10%. The specimens without the fly-ash served as the control. At the designed density of 1500kg/m3, the results for the control specimens at 28 day curing age was 3.74N/mm2. As for 50% sand replacement with fly-ash, the compressive strength were 2.37 N/mm, and 3.31 N/mm2 at 7-days 28-days curing age respectively, both satisfied the minimum compressive strength of 1.8N/mm2 and 2.5N/mm2 at the curing age of 7-days and 28-days respectively for conventional sandcrete block for building wall unit as allowed by Nigerian Industrial Standard (N.I.S). The result also shows an appreciable decrease in density of FSSB with 1411.8kg/m3, as compared to dense sandcrete solid block with average of 1950kg/m3, which will significantly reduce the overall dead load of the building structure. FSSB with 50% sand replacement with fly-ash also showed a much improved water absorption capacity of 9.81% as control specimen of 11.73%. Fly-ash can be used to reduce the quantity of sand used in FSSB production; thus ridding our environment of potentially harmful wastes, as well as reduce the consumption of non-renewable resources. Keywords— Foamed Sandcrete, Compressive Strength, fly-ash, dry density, stability, cement

Effect of fungal degradation on physicochemical properties of exploited stumps of oriental beech over a 25-year felling period and the obtained Kraft pulp properties

Oriental beech (Fagus orientalis Lipsky) is the most important and valuable industrial wood species in the Hyrcanian forests in the north of Iran mainly used for furniture, veneer, composite, and papermaking industries. The present research was conducted in 2014 aimed at investigating the physicochemical changes of the felled oriental beech stumps over a 2–25 year period, and likewise the feasibility of using the given stumps as an alternative resource for wood pulp production. To do so, the effects of in-situ decay of beech stumps on their physical (wet and dry weights of wood, wet apparent density, and dry apparent density) and chemical (cellulose, hemicellulose, lignin, extractives, and total mass of carbohydrates) properties over a 2–25 year felling period were studied. The effects of the given decay period were also studied on the obtained Kraft pulp yield and Kappa number. The results indicate that the wet and dry apparent densities as well as the wet and dry weights of the wood samples decreased over the study period. Also, the results show that approximately 30% of the total mass of carbohydrates was degraded by the ambient fungi over the initial two years of felling, whereas the same property was reduced by 60% after 25 years. The Kraft pulp yields obtained from 2- and 25-year decayed stumps were 22.5% and 8.4%, respectively. The fungal degradation of wood chemical compounds could considerably reduce pulp yield and Kappa number by 62.8% and 74.2%, respectively. The results of a stepwise multivariate regression model evidence that cellulose not only affects the Kappa number but also owns a greater share (vs. lignin) in modelling the Kappa number. This reveals that the intensity of cellulose degradation, due to fungal exposure, is significantly higher than that of the other components of beech stumps in the studied forest area.

Investigation on the effectiveness of electrolyzed water in controlling the early age properties of cement mortar

Abstract The use of electrolyzed water is expected to be a unique alternative approach to early repair of structural concrete and step up the construction process. The present investigation reveals the effectiveness of electrolyzed water in controlling the physical and mechanical properties of cement mortar at the fresh and early hardened states. The mortar samples were made using distilled water and 30 min electrolyzed water to compare their properties. The effect of the electrolyzed water on the performance of mortar was evaluated by analyzing setting times, flowability, dry and wet bulk density, apparent porosity, water absorption, and mechanical strengths such as compressive and flexural strength. Analyzing the results critically, it is demonstrated that the use of electrolyzed water sets the cement faster (reduces initial and final setting time by 41 min and 64 min, respectively) and shows higher compressive (17, 16, and 13%) and flexural (19, 12, and 10%) strengths than that of the normal distilled water-based mortar at the early ages of curing (1, 3, and 7 days of curing, respectively). Finally, based on the microstructure analysis and X-ray diffraction, a plausible mechanistic model is designed to elucidate the overall performances of the electrolyzed water-based mortar.

Implementation of random forest in geo-acoustic study

The correlation between sediment sound velocity (V) and physical properties has been studied for 60 years using empirical formulas and found to be difficult to predict V accurately. Random forest (RF) is a scientific discipline and a method of data analysis that automates analytical model building. Here, we present the implementation of the RF algorithm in V prediction and sediment classification. The goal of this study is to establish a predictive model based on RF using multiple physical parameters (mean grain size, porosity, wet bulk density, and water content). Compared to empirical formulas, the average error of RF velocity is only 0.95%, ranging from 0.03% to 2.73%, which has improved the accuracy of V prediction. We also used Mean Decrease Impurity importance to evaluate the importance of a variable and found that the most important feature in the predictive model is the mean grain size. The classification model based on RF reaching up to 75% accuracy in the dataset. Multiple features, such as physical properties, sedimentary environment, and sediment source, affect the geo-acoustic properties of sediments. The next goal is to use multiple features to improve the model and further improve the accuracy of sound velocity prediction and sediment classification.

STRENGTH CHARACTERISTICS OF ALCCOFINE BASED LIGHT WEIGHT CONCRETE

Concrete being an important material for construction of various structures has severe demand in the present trend of construction industry. Aggregate occupies the major quantity (70% approx.) of concrete based on which characteristics like compressive strength and porosity are controlled. The present usage of aggregate for construction is resulting in the depletion of the natural resources as well as it is showing a great impact on the environment. The work is to focus on the strength characteristics of concrete using coconut shell as an alternative material obtained from coconut processing units. Based on earlier studies a nominal amount of 30% replacement of natural coarse aggregate with coconut shell has been fixed. 'Alccofine' is used as a mineral admixture by replacing cement at various proportions in order to supplement the loss of strength. Tests have been carried out to find out the dry density, wet density and compressive strength. Comparison of the results show that the 30CS A8 (M4) achieving less density without compromising the strength.

A hybrid computational intelligence approach for predicting soil shear strength for urban housing construction: a case study at Vinhomes Imperia project, Hai Phong city (Vietnam)

This research proposes an alternative for estimating shear strength of soil based on a hybridization of Support Vector Regression (SVR) and Particle Swarm Optimization (PSO). SVR is used as a function approximation method for making prediction of the soil shear strength based on a set of twelve variables including sample depth, sand content, loam content clay content, moisture content, wet density, dry density, void ratio, liquid limit, plastic limit, plastic index, and liquid index. The hybrid framework, named as PSO–SVR, relies on PSO, as a metaheuristic, to optimize the training phase of the employed function approximator. A data set consisting of 443 soil samples associated with the experimental results of shear strength has been collected from a housing project in Vietnam. This data set is then used to train and verify the performance of the PSO–SVR model specifically constructed for shear strength estimation. The hybrid model has achieved a good modeling outcome with Root Mean Square Error (RMSE) = 0.038, Mean Absolute Percentage Error (MAPE) = 9.701%, and Coefficient of Determination (R2) = 0.888. Hence, the PSO–SVR model can be a potential alternative to be participated in the design phase of high-rise housing projects.