Pitthaya Jamsawang

Flexural Strength Characteristics of Compacted Cement-Polypropylene Fiber Sand

AbstractAn improvement of flexural strength of cement stabilized sand using polypropylene fibers designated as compacted cement-polypropylene fiber-sand (CCFS) is investigated in this research. The studied material performance of the CCFS includes postpeak behavior, toughness, and equivalent flexural strength ratio. The fiber inclusion significantly improves the postpeak flexural behavior, which is a requirement for bound pavement materials. The first peak flexural strength f1 and stiffness of both compacted-cement-sand (CCS) and CCFS are essentially the same for the same cement content. For low fiber content, the fiber inclusion primarily prevents the sudden failure. The CCFS exhibits deflection-hardening behavior and the peak flexural strength (fp) is higher than the first peak flexural strength (f1) for medium to high fiber contents. Two modes of failure are noted: single failure plane and stress transfer–induced multiple cracks. For low to medium fiber contents, the single failure plane is observed fo...

Efficiency of Rice Husk Ash as Cementitious Material in High-Strength Cement-Admixed Clay

The potential and efficiency of using rice husk ash (RHA) to add up or partially replace Portland cement in deep cement mixing technique are examined. A series of unconfined compression tests on cement-RHA-stabilized clay are conducted to investigate the influence of RHA on the mixture properties. Special attention is paid to its efficiency for increasing the strength by partial cement replacement to obtain high-strength soil cement, and it is compared with fly ash. Test results indicate that up to 35% of RHA could be advantageously added up to enhance the strength if the cement content in the mixture is larger than 10%. The RHA enhances the strength of cement-admixed clay by larger than 100% at 28 days. For curing time of 14 and 28 days, the RHA exhibits higher efficiency on Portland cement replacement when the cement and overall cementitious contents are not less than 20 and 35%, respectively. The optimum condition for high-strength mixture is achieved when RHA is added to the 20% cement content mixture. When compared with fly ash of similar grain size, the efficiency of RHA is higher when the content to be added is greater than 15%. This indicates the suitability of RHA for use in high-strength soil-cement.