Evaluation of Resilient Modulus for Lime- and Cement-Stabilized Synthetic Cohesive Soils

1997 ◽  
Vol 1589 (1) ◽  
pp. 70-75 ◽  
Author(s):  
Francis Achampong ◽  
Mumtaz Usmen ◽  
Takaaki Kagawa
Keyword(s):  
Resilient Modulus ◽  
Mineralogical Composition ◽  
Cohesive Soils ◽  
High Plasticity ◽  
Regression Equations ◽  
Predictive Regression ◽  
Deviator Stress ◽  
Curing Period ◽  
Student’S T ◽  
Stabilizer Type

The effects of deviator stress, molding moisture content, stabilizer type and content, curing period, and soil type on the resilient modulus (Mr) of lime- and cement-stabilized cohesive soils were investigated by using Hydrite R (kaolinite) and sodium bentonite (montmorillonite) blends. It was found that Mr increases with decreasing deviator stress, increasing lime and cement content, and extended curing period. Moisture variations around optimum had little effect on Mr with higher lime contents. Multiple regression analyses and Student's t-tests indicated that all the factors investigated were significant and could be related to Mr by predictive regression equations. For a given stabilizer type and content, the low-plasticity clay (CL) soil produced the best results. The cement-stabilized CL soil normal cured for 28 days produced the highest Mr value. However, cement stabilization was not found to be very effective for the high-plasticity clay (CH) soil. Mineralogical composition has a marked effect on the Mr of lime and cement-stabilized cohesive soils. Kaolinitic CL soils work better than montmorillonitic CH soils with both lime and cement.

Resilient modulus of cohesive soils and the effect of freeze–thaw

1995 ◽  
Vol 32 (4) ◽  
pp. 559-568 ◽  
Author(s):  
Woojin Lee ◽  
N.C. Bohra ◽  
A.G. Altschaeffl ◽  
T.D. White
Keyword(s):  
Resilient Modulus ◽  
Empirical Relationship ◽  
Cohesive Soil ◽  
Cohesive Soils ◽  
Unconfined Compression ◽  
Unconfined Compression Test ◽  
Freeze Thaw ◽  
Deviator Stress ◽  
A Value ◽  
Lens Formation

Resilient modulus tests were performed on five cohesive soils sampled from the subgrades of in-service pavements. The stress at 1% strain in the unconfined compression test (Su1.0%) was found to be a good indicator of the resilient modulus (MR), and an empirical relationship between MR and Su1.0% was obtained. The proposed relationship itself is not affected by the changes in subgrade after construction and, therefore, is applicable to as-compacted and in-service subgrade conditions. Closed-system freeze–thaw tests were also performed and the effect of freeze–thaw on the resilient modulus was studied. There is a negligible effect of freeze–thaw, without ice lens formation, for soils having values of Su1.0% less than 8 psi (55 kPa), while the effect of freeze–thaw increases as the value of Su1.0% increases. For example, a soil with a value of Su1.0% greater than 15 psi (103 kPa) would exhibit more than 50% reduction in resilient modulus due to the effect of freeze–thaw. The resilient modulus of frozen cohesive soil is independent of the repeated deviator stress. Key words : resilient modulus, subgrade, pavement, freeze–thaw.

scholarly journals Predictive Regression Equations of Flowmetric and Spirometric Peak Expiratory Flow in Healthy Moroccan Adults

2017 ◽  
Vol 2017 ◽  
pp. 1-7
Author(s):  
Khalid Bouti ◽  
Iliass Maouni ◽  
Jouda Benamor ◽  
Jamal Eddine Bourkadi
Keyword(s):  
Peak Flow ◽  
Adult Population ◽  
Cross Sectional Study ◽  
Regression Equations ◽  
Anthropometric Parameters ◽  
Cross Sectional ◽  
Flow Measurements ◽  
Predictive Regression ◽  
Final Sample ◽  
Main Determinants

Introduction. PEF has never been characterized among healthy Moroccan adults. The objective of this study is to describe the values of PEF among healthy Moroccan adults, to study its relationship with anthropometric parameters (gender, age, height, and weight), to compare spirometric and flowmetric PEF, to establish the prediction equations for PEF, and to study the correlation between PEF and FEV1. Methods. Cross-sectional study conducted between May and June 2016. It involved healthy nonsmoking volunteers living in Tetouan, Morocco, gathered through a mobile stand realization of spirometry and peak flow measurements. Results. Our final sample concerned 313 adults (143 men and 170 women). For both men and women, age and height were the main determinants of PEF, and a positive correlation was found between PEF and FEV1. Conclusion. Our study has established the PEF predictive equations in the Moroccan adult population. Our results allow us to conclude that the PEF can be a reliable alternative of FEV1 in centers not equipped with spirometry.

scholarly journals Influence of Gradation on Resilient Modulus of High Plasticity Soil-Gravel Mixture

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Chuang Liu ◽  
Tian-Zeng Ren ◽  
Rui Zhang ◽  
Qian-Feng Gao ◽  
Jian-Long Zheng
Keyword(s):  
Resilient Modulus ◽  
Economic Benefits ◽  
Construction And Demolition Waste ◽  
Triaxial Tests ◽  
High Plasticity ◽  
Demolition Waste ◽  
Gravel Content ◽  
Coarse Aggregates ◽  
Mixing Method ◽  
Skeleton Structure

Because of low resilient modulus, high plasticity soil is often not allowed to fill road subgrades and is discarded as construction and demolition waste (CDW). To make use of the CDW, this study explored the possibility of improving high plasticity soil with gravel and examined the effect of gravel gradation on the resilient modulus of the soil-gravel mixture. A series of dynamic triaxial tests, tests of voids in coarse aggregate, and X-ray CT scans were carried out on high plasticity soil-gravel mixtures of different gravel contents and gravel gradation types. The test results show that there is a critical gravel content, that is, 44.1%. When the gravel content is less than 44.1%, the mixture shows a dense suspended structure and its modulus increases slowly with increasing gravel content. When the gravel content is greater than 44.1%, the mixture exhibits a dense skeleton structure and the modulus increases rapidly as the gravel content rises. Moreover, as the gravel gradation tends to the lower type, coarse aggregates increase in quantity and contact each other to form a dense skeleton; thus, the modulus increases accordingly. As the gravel gradation approaches the upper type, coarse aggregates decrease in quantity and tend to suspend in the soil, so the modulus decreases. With the increase in contact number, the skeleton structure is continuously improved, and thus the modulus is enhanced progressively. The results indicate that the gravel mixing method with a gravel content of 40%–45% can effectively improve high plasticity soil and shows great environmental and economic benefits.

Prediction of Resilient Modulus of Compacted Cohesive Soils in South China

2019 ◽  
Vol 19 (7) ◽  
pp. 04019068 ◽  
Author(s):  
Junhui Zhang ◽  
Junhui Peng ◽  
Jianlong Zheng ◽  
Liangliang Dai ◽  
Yongsheng Yao
Keyword(s):  
South China ◽  
Resilient Modulus ◽  
Cohesive Soils

scholarly journals Mineralogical composition and physical characteristics of marly soils from Heraklion Crete

2001 ◽  
Vol 34 (3) ◽  
pp. 851
Author(s):  
Α. ΤΣΙΡΑΜΠΙΔΗΣ ◽  
Θ. ΠΑΠΑΛΙΑΓΚΑΣ
Keyword(s):  
Clay Minerals ◽  
Clay Fraction ◽  
Soil Classification ◽  
Mineralogical Composition ◽  
Liquid Limit ◽  
Silty Clay ◽  
High Plasticity ◽  
Degree Of Consolidation ◽  
Very High

The mainly white-yellow marly soils studied present medium degree of consolidation and induration. The predominant grain size of the non - carbonate constituents is that of silt varying from 34 to 64%. According to the textural classification of soils of the SSDS the samples are mainly silty-clay loams with moisture capacity 30-40%. In the untreated samples in decreasing abundance the following minerals predominate: calcite (31-59%), clay minerals (20-34%) and quartz (12-20%). In the clay fraction (<2μπι) in decreasing abundance the following clay minerals (in discrete and interstratified phases) predominate: illite, smectite and vermiculite. Chlorite and kaolinite are missing. Mineralogically the marly soils are immature, because of the extended presence of Fe-Mg minerals (i.e. amphiboles, pyroxenes and clay minerals). According to the Unified Soil Classification System of the ASTM the studied marly soils mainly belong to the groups MH and CH (inorganic silts and inorganic clays respectively with high plasticity and liquid limit >50%), as well as to the group CL (inorganic clays with low plasticity and liquid limit <50%). The degree of consolidation and induration, as well as of compaction of these soils is medium. They contain significant amounts of discrete or interstratified smectite and mainly present high to very high swelling potential and activity between 0.5 and 2.0. It is concluded that specific precautions must be taken into account, when it is unavoidable the foundation of various constructions on these marly soils, because they swell and shrink extensively.

scholarly journals Accelerometer-based prediction of ground reaction force in head-out water exercise with different exercise intensity countermovement jump

2022 ◽  
Vol 14 (1) ◽  
Author(s):  
Kuei-Yu Chien ◽  
Wei-Gang Chang ◽  
Wan-Chin Chen ◽  
Rong-Jun Liou
Keyword(s):  
Ground Reaction Force ◽  
Reaction Force ◽  
Body Height ◽  
Force Plate ◽  
Prediction Equation ◽  
Regression Equations ◽  
Countermovement Jump ◽  
Predictive Regression ◽  
Seventh Cervical Vertebra ◽  
The Impact

Abstract Background Water jumping exercise is an alternative method to achieve maintenance of bone health and reduce exercise injuries. Clarifying the ground reaction force (GRF) of moderate and high cardiopulmonary exercise intensities for jumping movements can help quantify the impact force during different exercise intensities. Accelerometers have been explored for measuring skeletal mechanical loading by estimating the GRFs. Predictive regression equations for GRF using ACC on land have already been developed and performed outside laboratory settings, whereas a predictive regression equation for GRF in water exercises is not yet established. The purpose of this study was to determine the best accelerometer wear-position for three exercise intensities and develop and validate the ground reaction force (GRF) prediction equation. Methods Twelve healthy women (23.6 ± 1.83 years, 158.2 ± 5.33 cm, 53.1 ± 7.50 kg) were recruited as participants. Triaxial accelerometers were affixed 3 cm above the medial malleolus of the tibia, fifth lumbar vertebra, and seventh cervical vertebra (C7). The countermovement jump (CMJ) cadence started at 80 beats/min and increased by 5 beats per 20 s to reach 50%, 65%, and 80% heart rate reserves, and then participants jumped five more times. One-way repeated analysis of variance was used to determine acceleration differences among wear-positions and exercise intensities. Pearson’s correlation was used to determine the correlation between the acceleration and GRF per body weight on land (GRFVLBW). Backward regression analysis was used to generate GRFVLBW prediction equations from full models with C7 acceleration (C7 ACC), age, percentage of water deep divided by body height (PWDH), and bodyweight as predictors. Paired t-test was used to determine GRFVLBW differences between values from the prediction equation and force plate measurement during validation. Lin’s CCC and Bland–Altman plots were used to determine the agreement between the predicted and force plate-measured GRFVLBW. Results The raw full profile data for the resultant acceleration showed that the acceleration curve of C7 was similar to that of GRFv. The predicted formula was − 1.712 + 0.658 * C7ACC + 0.016 * PWDH + 0.008 * age + 0.003*weight. Lin’s CCC score was 0.7453, with bias of 0.369%. Conclusion The resultant acceleration measured at C7 was identified as the valid estimated GRFVLBW during CMJ in water.

scholarly journals Ceramic raw materials from the State of Maranhão, Brazil. Part 1: chemical and mineralogical characterization and technological properties of clays from São Luis, Rosário, Pinheiro and Mirinzal

2012 ◽  
Vol 65 (4) ◽  
pp. 513-521
Author(s):  
José Manuel Rivas Mercury ◽  
Gricirene Sousa Correia ◽  
Nazaré Socorro Lemos Silva Vasconcelos ◽  
Aluísio Alves Cabral Jr. ◽  
Rômulo Simões Angélica
Keyword(s):  
Raw Materials ◽  
Mineralogical Composition ◽  
Exchange Capacity ◽  
High Plasticity ◽  
X Ray Diffraction ◽  
Specific Mass ◽  
Mineralogical Characterization ◽  
Heat Treated ◽  
Heavy Clay

This work involved the characterization of clays collected in the municipalities of São Luis, Rosário, Pinheiro and Mirinzal (state of Maranhão, Brazil), based on specific mass, specific surface area, cation exchange capacity (CEC), particle size distribution, X-ray diffraction (XRD), differential thermal analysis (DTA), thermogravimetric analysis (TG-DTA) and Atterberg limits. Technological tests for ceramic applications were also carried out on compacts pressed under 20 MPa and heat-treated at 850, 950, 1050, 1150 and 1250ºC. Our results indicated that two of the clays composed of kaolinite, quartz, and anatase with high plasticity limits, have excellent properties and can be used in the whiteware industry. The other ones are red-firing clays and have a mineralogical composition of quartz, kaolin, feldspar, montmorillonite, hematite and goethite. The latter showed low and moderate values of plasticity, which makes them suitable for the production of heavy clay products.

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