Clays treated with lower cement contents often exhibit behaviour similar to stiff clays with planar failure surface under triaxial compression. In the present work the behaviour of a marine clay treated with 5 % cement, subjected to undrained triaxial compression tests is studied. The pre-consolidation pressure of the cemented clay due to the cementation bonding is observed to be very high. It is attempted to model the behaviour of cement treated clay using a bounding surface plasticity formulation as the plastic behaviour of the cemented clays within the yield surface has to be considered. The effect of cementation is included in the model as the pre-consolidation pressure obtained from consolidation tests. The tensile strength due to cementation bonds is included in the equation of the bounding surface. Simulations of the undrained triaxial compression tests on cemented clays are carried out and the results are validated with the experimental results.
The deep cement mixing (DCM) method is one of the popular methods of ground-improvement techniques for enhancing the bearing capacity and reducing settlements of thick deposits of soft clay with high water content. High cement content, of the order of 10 % to 25 %, are often used in practice. To reduce the requirement of cement, an attempt is made in the present study to replace the cement partially with fly ash, as a fly ash–cement composite. Different percentages of Class F fly ash (10 %, 20 %, and 30 %) to Ennore marine clay with different proportions of cement (10 %, 15 %, and 20 %) were added and tested. The optimum clay water content at which maximum strength is achieved was determined for various mixes based on unconfined compressive strength tests. A detailed study showed that addition of 20 % Class F fly ash is effective in all combinations. The behavior of the composite under one-dimensional consolidation was also tested.
This paper investigates lateral pressure on formwork indirectly by measuring lateral deflection using an innovative device. This device is fabricated from Polyvinyl Chloride (PVC) cylindrical mold in a fashion allowing occurrence and measurement of lateral movement at different depths using dial gauges. The lateral deflections for different systems of filling materials including water, sand, self-compacting concrete (SCC), and flowing concrete. The flowing concrete is tested under two conditions, vibrated (NVC), and non-vibrated (NCno.V). The results show that the NVC produced the largest lateral deflection which attributed to the vibration pressure. The measured lateral deflection are ranked descending in the following order: NVC, Water, SCC, NCno.V and Sand.
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