Use of cement by-pass dust in soil stabilization

Cement by-pass dust (CBPD) or cement kiln dust (CKD) is a by-product of the manufacture of Portland cement. It is generated during the calcining process in the kiln. Lime (CaO) constitutes more than 60% of CBPD composition. Other compounds include SiO₂, Al₂O₃, Fe₂O₃, K₂O, Na₂O, Cl^-, etc. Oman Cement Company generates about 25,000 to 30,000 tons of CBPD every year. Some CBPD is used as a filler for road asphalting. The remainder of the CBPD is disposed of on-site without any further reuse or reclamation. As such, research was carried out to investigate beneficial reuses of CBPD in the Sultanate of Oman. This paper presents the results of a study that investigated the use of CBPD in the stabilization of an expansive clay. The soil was stabilized with 0, 3, 6, and 9% CBPD. Mixtures were subjected to the following tests: (1) Atterberg limits, (2) pH, (3) compaction, (4) California Bearing Ratio (CBR), (5) swell percent, and (6) swell pressure. Results indicate that as cement by-pass dust content increases, the swell percent and maximum dry density decrease while the pH and CBR values tend to increase. Thus, CBPD could potentially act similar to lime or cement in improving the properties of clayey or silty soils.