S.a. Naeini, R. Ziaie_moayed,
Volume 7, Issue 2 (6-2009)
Abstract
In recent years, soil reinforcement is considered of great importance in many different civil projects. One of
the most significant applications of soil reinforcement is in road construction. Sub grade soil and its properties are
very important in the design of road pavement structure. Its main function is to give adequate support to the pavement
from beneath. Therefore, it should have a sufficient load carrying capacity. The use of geosynthetics in road and
airfield construction has shown the potential to increase the soil bearing capacity. One category of geosynthetics to
particular, geogrid, has gained increasing acceptance in road construction. A geogrid is a geosynthetic material
consisting of connected parallel sets of tensile ribs with apertures of sufficient size to allow strike-through of
surrounding soil, stone, or other geotechnical material. Geogrid reinforcement of sub grade soil is achieved through
the increase of frictional interaction between the soil and the reinforcement. Geogrid have been successfully used to
provide a construction platform over subgrades. In this application, the geogrid improves the ability to obtain
compaction in overlying aggregates, while reducing the amount of material required be removing and replacing.
Relative agreement exists that substantial benefits can be achieved from the inclusion of geogrids within the pavement
systems however, the quantity of the improvement is in relative disagreement. This paper presents the effects of
plasticity index and also reinforcing of soft clay on CBR values. Three samples of clay with different plasticity index
(PI) values are selected and tested without reinforcement. Then by placing one and two layer of geogrid at certain
depth within sample height, the effects of reinforcement and PI on CBR values are investigated in both soaked and
unsoaked conditions. The results shows that as the PI increase the CBR value decreases and reinforcing clay with
geogrid will increase the CBR value.
Malik Shoeb Ahmad, S. Salahuddin Shah,
Volume 8, Issue 4 (12-2010)
Abstract
Roadways have a high potential for utilization of large volume of the fly ash stabilized mixes. In this study, an attempt has been made to investigate the use of Class F fly ash mixed with lime precipitated electroplating waste sludge–cement as a base material in highways. A series of tests were performed on specimens prepared with fly ash, cement and lime precipitated waste sludge. California bearing ratio (CBR) tests were conducted for 70%-55%fly ash, 8%cement, and 30%-45%waste sludge combinations. Results show that the load bearing strength of the mix is highly dependent on the waste sludge content, cement as well as curing period. The CBR value of fly ash mixed with electroplating waste sludge and cement has been increased to manifold and results the reduction in the construction cost of the pavement. The study also encourages the use of two potentially hazardous wastes for mass scale utilization without causing danger to the environment, vegetation, human and animal lives.
Volume 15, Issue 6 (9-2017)
Abstract
In this study, the shear strength parameters of the Kaolinite clay, as the control material, and the Kaolinite clay reinforced by different percentages of two different types of crumb rubber content have been evaluated. The consolidated drained and unconsolidated undrained triaxial and California bearing ratio tests have been conducted on the control and crumb rubber reinforced soils. Addition of crumb rubber would improve shear strength parameters such as cohesion, friction and dilation angles, stiffness and the ductility of the reinforced soil. 5, 10 and 15 % (by the weight of dry soil) of crumb rubber content were used in this study which were undergone confining stress levels of 100, 200 and 300 kPa and an optimum crumb rubber content is found, which results in the maximum bearing capacity of the soil. Also, due to the non-linearity of the failure mode of reinforced soil and inadequacy of Mohr–Columb envelope for describing the behaviour, a failure mode is proposed for the clay soils reinforced by crumb rubber. This failure criterion is useful for failure envelope of clay-rubber matrix.
