scholarly journals Study on performance of old composite pavement reclaimed material in cement stabilized macadam base

2018 ◽  
Vol 53 ◽  
pp. 01041
Author(s):  
Yuxuan Yang ◽  
Peng Xiao ◽  
Shanshan Xu ◽  
Tong Wang
Keyword(s):  
Cement Content ◽  
Total Content ◽  
Recycled Aggregate ◽  
Cement Concrete ◽  
Compressive Strength Test ◽  
Cement Concrete Pavement ◽  
Negative Effect ◽  
Dry Shrinkage ◽  
Shrinkage Property

For the old composite pavement, there are two regeneration methods: the overall recycling asphalt pavement and the cement concrete pavement and the Stratified recovery. C-B-3 gradation and cement content of 5% were used. The total content of recycled aggregate is 0, 30%, 50%, 70% and 100% and the proportion of RA and RAP is about 1:2. Through compaction test， unconfined compressive strength test and dry shrinkage test, studying the feasibility of recycling composite pavement to cement stabilized macadam base. The results show that the strength of recycled cement stabilized macadam is generally higher than that of ordinary cement stabilized macadam. The strength of regenerated cement stabilized macadam can meet the strength requirements under most traffic volume of the highways in the standard. The gradation of the mixture by stratified recovery is more uniform and the quality of the mixture can be better controlled. The addition of NA has a negative effect on the dry shrinkage properties of recycled cement stabilized macadam. However, mixing RAP into recycled cement stabilized macadam can reduce the sensitivity of materials to water and enhance the dry shrinkage property of materials.

scholarly journals Laboratory Investigation on the Performance of Cement Stabilized Recycled Aggregate with the Vibration Mixing Process

2020 ◽  
Vol 2020 ◽  
pp. 1-11 ◽  
Author(s):  
Yongliang Wang ◽  
Jinbao Zhang ◽  
Xuetao Wang ◽  
Zhi Zhang
Keyword(s):  
Compressive Strength ◽  
Cement Content ◽  
Strength Test ◽  
Recycled Aggregate ◽  
Mixing Process ◽  
Optimum Parameters ◽  
Compressive Strength Test ◽  
Interface Transition Zone ◽  
Dry Shrinkage ◽  
Vibration Time

The objective of this article is to investigate the effect of the vibration mixing process (VMP) on the performance of cement stabilized recycled aggregate (CSRA). The ordinary mixing process (OMP) was also used for comparative analysis with the VMP. The performance of CSRA with different cement content was tested and comprehensively analyzed by the unconfined compressive strength test, dry shrinkage test, and temperature shrinkage test. The results showed that compared with OMP, VMP can greatly improve the compressive strength, dry shrinkage, and temperature shrinkage properties of CSRA. The optimum parameters of vibration time and vibration frequency in VMP were 30 s and 40 Hz, respectively. The reason why VMP can improve the performance of CSRA was that VMP strengthened the aggregate and interface transition zone and introduced microbubbles to optimize the pore structure.

Influences on the Axle Load Stress of the Cement-Concrete Pavement Structure Caused by the Crack or Cutting Crack of the Semi-Rigid Base

2013 ◽  
Vol 857 ◽  
pp. 200-203
Author(s):  
Bin Yang ◽  
Hua Tan ◽  
Jia Xi Deng ◽  
Chan Pang
Keyword(s):  
Working Conditions ◽  
Crack Width ◽  
Concrete Pavement ◽  
Rigid Base ◽  
Cement Concrete ◽  
3D Fem ◽  
Cement Concrete Pavement ◽  
Dry Shrinkage ◽  
Pavement Structure ◽  
The One

Some horizontal cracks will appear during the strength formation of the semi-rigid base, for the influences of dry shrinkage and temperature shrinkage exist, so the engineers often adopt the manual method of equidistant cutting crack to avoid the irregular cracks. In order to analyse the influences on the axle load stress of the cement-concrete pavement slab which caused by the width and position of the base cracks or cutting cracks, the 3D FEM was used to study them under the different working conditions considering the crack, width and position. By the above research, the results show the existing cracks affect the integrity and continuity of the pavement structure; The crack width has no large influence on the stress of the pavement slab, while the base stress decreases apparently with the increasing width, and it becomes stable finally; The stress of the pavement slab is maximum when the crack or cutting crack is located in the middle, while it's small when the crack or cutting crack is located in the one fourth of the pavement slab.

The Optimized Design for Groove Parameters Based on Cement Pavement Materials Performance

2011 ◽  
Vol 213 ◽  
pp. 613-617
Author(s):  
Yong Shou Yang ◽  
Xiong Yi ◽  
Peng Hu ◽  
Qiang Dong
Keyword(s):  
Theoretical Analysis ◽  
Laboratory Tests ◽  
Optimal Choice ◽  
Concrete Pavement ◽  
Service Performance ◽  
Optimized Design ◽  
Cement Concrete ◽  
Pavement Materials ◽  
Cement Concrete Pavement

Aiming at the service performance characteristics of cement concrete pavement, this paper puts forward optimized design concept for groove parameters of cement pavement. Single groove parameter optimal choice is systematically analyzed based on integrated service quality of cement pavement. Through a variety of multi-contrast laboratory tests and theoretical analysis, from three aspects of anti-slide, strength, and noise reduction, optimized design scheme of groove parameters are demonstrated and proposed, and groove parameters and form suitable for environment characteristics in seasonal frozen region are given.

Design Countermeasures of Preventing Frost Heaving of the Airport Cement Concrete Pavement in Cold Area

2014 ◽  
Vol 587-589 ◽  
pp. 1106-1109 ◽  
Author(s):  
Bao Hua Shi ◽  
Ping Mei ◽  
Ya Men Zhang ◽  
Bing Cao
Keyword(s):  
Drainage System ◽  
Frost Damage ◽  
Cement Concrete ◽  
Design Quality ◽  
Performance Requirements ◽  
Basic Performance ◽  
Cement Concrete Pavement ◽  
Cold Area ◽  
Frost Layer

In order to guarantee the design quality of the pavement in a cold area, by analyzing the nature conditions in the area, such a cold and long winter, short summer and high altitude, based on the reason of road frost damage, not only submit the design measure according to the basic performance requirements of structure of materials and the thickness of frost layer, but also submit the design measures according to provision of drainage system, isolated layers and blocking groundwater sources..

Dry Shrinkage, Frost Resistance and Permeability of Rubber Included Concrete

2006 ◽  
Vol 302-303 ◽  
pp. 120-124 ◽  
Author(s):  
Ya Mei Zhang ◽  
Shen-Xia Chen ◽  
Bo Chen ◽  
Wei Sun
Keyword(s):  
Frost Resistance ◽  
Preliminary Investigation ◽  
Cement Concrete ◽  
Rubber Powder ◽  
Waste Tires ◽  
Cement Mortars ◽  
Rubber Particles ◽  
Negative Effect ◽  
Dry Shrinkage ◽  
Positive Effect

This paper presents a preliminary investigation on dry shrinkage, frost resistance and permeability of rubber included concrete. The results show that rubber particles from waste tires are beneficial to reduction of dry shrinkage of cement mortars due to their soft characteristics. The addition of rubber powder in cement concrete can greatly improve frost resistance of concrete. However, coarse rubber particles (3~4 mm in diameter) seem to have little positive effect to frost resistance. The addition of proper amount of rubber in concrete can reduce permeability of concrete, but excessive rubber can have negative effect.

Vocation Education Quality from Demand Side’s Perspective: The Case of Transport Technology Universities in the North of Vietnam

2019 ◽  
Vol 10 (11) ◽  
pp. 1089-1097
Author(s):  
Nguyen Quynh Hoa ◽  
◽  
Phung Chu Hoang ◽  
Keyword(s):  
Vocational Training ◽  
Vocational Education And Training ◽  
Quality Outcomes ◽  
The North ◽  
Job Opportunities ◽  
Management Capacity ◽  
Negative Effect ◽  
Training Quality ◽  
And Training

Quality outcomes from vocational education and training (VET) are fundamental to ensuring a skilled workforce and supporting a productive economy. The quality of vocational training from the demand’s perspective is defined as meeting the customer specification, needs or requirements. Using the method of Exploratory Factor Analysis (EFA) and Multiple Regression Analysis to get the analytical results of 275 respondents as graduates of University of Transport and Communication, University of Transport Technology (the two universities training on transportation in the North of Vietnam), the results show that factors are measured by the observed variables in the study that ensure reliability and relevance. The descriptive statistics result of vocational training quality is 3.28, while all independent variables are at average level (between 3.1 to 3.48) with the highest value related to the quality of the teacher and the lowest are facilities and training programs and management capacity of university. However, the regression results show that the qualification of the teacher, material facilities and training program, management capacity and job opportunities at the training school do not affect the quality of the training while “Learners-NH” have a great positive effect and the labor market information has a negative effect on the training quality of the school significantly. Base on those data, some policy recommendations have been given out in order to improve the training quality of transport technology universities in the north of Vietnam in particular and the vocational training quality of Vietnam in general.

The Impact of Competitive Quasi-Market on Service Delivery in Benue State University, Makurdi Nigeria

GIS Business ◽  
2019 ◽  
Vol 14 (4) ◽  
pp. 85-98
Author(s):  
Idoko Peter
Keyword(s):  
Service Delivery ◽  
A Priori ◽  
Least Square ◽  
Secondary Source ◽  
State University ◽  
Ordinary Least Square ◽  
Negative Effect ◽  
The Impact ◽  
The Relationship

This research the impact of competitive quasi market on service delivery in Benue State University, Makurdi Nigeria. Both primary and secondary source of data and information were used for the study and questionnaire was used to extract information from the purposively selected respondents. The population for this study is one hundred and seventy three (173) administrative staff of Benue State University selected at random. The statistical tools employed was the classical ordinary least square (OLS) and the probability value of the estimates was used to tests hypotheses of the study. The result of the study indicates that a positive relationship exist between Competitive quasi marketing in Benue State University, Makurdi Nigeria (CQM) and Transparency in the service delivery (TRSP) and the relationship is statistically significant (p<0.05). Competitive quasi marketing (CQM) has a negative effect on Observe Competence in Benue State University, Makurdi Nigeria (OBCP) and the relationship is not statistically significant (p>0.05). Competitive quasi marketing (CQM) has a positive effect on Innovation in Benue State University, Makurdi Nigeria (INVO) and the relationship is statistically significant (p<0.05) and in line with a priori expectation. This means that a unit increases in Competitive quasi marketing (CQM) will result to a corresponding increase in innovation in Benue State University, Makurdi Nigeria (INVO) by a margin of 22.5%. It was concluded that government monopoly in the provision of certain types of services has greatly affected the quality of service experience in the institution. It was recommended among others that the stakeholders in the market has to be transparent so that the system will be productive to serve the society effectively

INFLUENCE OF DICARBOXYLIC ACIDS ON SOWING QUALITY OF SPRING BARLEY

1970 ◽  
pp. 22-25
Author(s):  
N. N. Loy ◽  
S. N. Gulina
Keyword(s):  
Organic Acids ◽  
Spring Barley ◽  
Dose Range ◽  
Dicarboxylic Acids ◽  
Rotary Machine ◽  
Working Solution ◽  
Negative Effect ◽  
Sprouted Seeds

The effect of presowing seed treatment on various concentrations of dicarboxylic (organic) acids on the sowing characteristics of spring barley has been studied. Seeds were treated with organic acids obtained by exposing cuttings to the radiation with a dose of 100 kGy and consequent hydrolysis, in concentrations: 1•10-7 %; 1•10-9; 1•10-11; 1•10-13 and 1•10-15 % on a laboratory rotary machine RVO-64 for one day before laying for germination. Distilled water was used for the control case. The rate of application of the working solution calculated as 10 liters / ton of seeds. Seeds were germinated in filter paper rolls in accordance with GOST 12038-84 requirements. The temperature was maintained at +24 ° C in the thermostat where the glasses with rolls were placed. For determination of germinative power and laboratory germination the sprouted seeds were evaluated after three and seven days, respectively. In laboratory experiments it was established that the treatment of barley seeds of varieties Zazersky 85, Nur and Vladimir with organic acids (OK) in different concentrations had both a stimulating and a negative effect. On the Zazersky 85 variety, in variants with acid concentrations of 1•10-9 and 1•10-11, an increase in germination energy (EP) by 2-4% and a significant decrease (by 3-4%) of laboratory germination (LV) of barley seeds were noted. On the Nur variety, the increase in EP was observed at 4% (concentration 1•10-11), LV and seed growth force (CPC) by 2-7% at a concentration of 1•10-7 and in the dose range 1•10-11 - 1•10-14 compared to the control values. On the grade of Vladimir, an increase in EP, LV, and CPC was found to increase by 1-6% at concentrations OK 1•10-7 and 1•10-13. It was shown that the treatment of seeds with acids led to an increase in the length of the germ in all studied varieties (by 3-9%) and dry biomass of 7-day-old seedlings - by 3-6%. Consequently, the treatment of seeds with a mixture of dicarboxylic acids has a stimulating effect on the sowing quality of spring barley.

Beech sapling architecture following small and medium gap disturbances in silver fir-beech old-growth forests in Slovenia

2005 ◽  
Vol 156 (12) ◽  
pp. 481-486 ◽  
Author(s):  
Jurij Diaci ◽  
Lahorka Kozjek
Keyword(s):  
Light Intensity ◽  
Quality Characteristics ◽  
Stem Length ◽  
Silver Fir ◽  
Beech Forests ◽  
Vertical Growth ◽  
Relative Light Intensity ◽  
Stem Bending ◽  
Negative Effect

The objective of our research was to examine the effect of canopy shading on beech sapling architecture in the oldgrowth silver fir-beech forests of Pecka and Rajhenavski Rog. In August 2003 we sampled one plot (352 m2) in a large gap in Pecka, which was a result of a strong windstorm in 1983, and eight small gaps (26–78 m2) with similar sapling heights (3.8–8 m). A ground view of each gap was drawn including the characteristics of gap border trees and the density of separate sapling layers was recorded. The height and diameter were measured for each sapling, as well as the following quality characteristics on selected dominant saplings: width of the crown,number of larger branches and knots (&gt;1/3 DBH), intensity of stem bending, deviation from vertical growth, number of terminal shoots, and the type of damage. The results show a negative effect of high canopy shading (estimated relative light intensity was below 5%) on the architectural quality of saplings. A lower overall density of saplings, greater intensity of bending and deviation from vertical growth, a shorter stem length without branches, a larger number of saplings with two terminal shoots, and a larger number of damaged saplings were observed in small gaps.

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