Improving California Bearing Ratio (CBR) Using Chemical and Physical Treatments for Diyala Soils

Abstract

Gets in the world at this time continued growth and rapid development in the whole aspects of life. The urgent needing accomplished that is in civil engineering demands like the construction of houses, schools, hospitals, roads, and other structures. Because of that and for economic and security reasons; classifying soil and knowing its bearing capacity appeared to be very necessary conditions that offer a large domain of benefits that could not be counted. This study focused on classifying and determining the bearing capacity of some samples of soil that classified as soft soils of Baquba city the center of Diyala governorate in Iraq. Then trying to increase their bearing capacity. The California Bearing Ratio (CBR) was used in the paper to define soil strength because it is considered a force measuring parameter. Five elected physical and chemical treatments were used in predetermined percents taken from the literature and suited the kind of soil. They were quicklime, class F fly ash activated by cement, rock powder, crushed waste concrete, and crumb rubber of tires. The treatment that was the best among the five used methods was by the rock powder that improved CBR value by 570% in soil samples A used.

Conclusions

From the foregoing, the following conclusions can be drawn:

• There are soils with problems in some locations in the Diyala governorate that need geotechnical treatment before building projects on them.
• All the five stabilizers used in the paper gave positive results, and the taken soils responded to them.
• The ideal fixator in this study can be considered the rock powder, which was proven by the results of its treatment as if it was a cement stabilizer or an alternative substitute for it in stabilizing the soil.
• The California Bearing Ratio (CBR) test can be considered a very successful experiment and is ideal for measuring the tolerance and resistivity of soils.
• Soil was the most responsive to treatment with the five additives is soil A, and this may be attributed to the weakness of this soil represented by its high activity. Besides, although it is classified according to the USCS system as the remaining two soils B and C being three clay soils of low plasticity (CL), but we note of AASHTO's Sample A classification A-7-6(35), it is the weakest of the three soils.
• Soils first in response to treatment are followed by soils B and then C as a possibility for AASHTO classification of them; A-6(18) for soil B and A-6(12) for soil C.
• The success of using industrial stabilizers (lime and cement) and residues (fly ash, rock powder, waste concrete, and crumb rubber of tires) in stabilizing the soil is the success of having structural, economic, and environmentally friendly benefits.