Chloride-binding capacity of mortars composed of marine sand subjected to external chloride penetration

In order to explore the interactional relations of internal chloride and external chloride-binding amongst the cementitious materials,the chloride-binding capacity of mortars composed of marine sand(MS)or washed marine sand(WMS)were investigated.Results indicate that more external chloride can penetrate and diff use more deeply into the WMS mortar than that in the MS mortar.This phenomenon suggests that the external chloride migration resistance due to WMS is lower than that caused by MS.The distribution trends of the bound chloride content in the two types of mortars are the same at diff erent immersion times.However,a signifi cantly decreased area of the bound chloride content exists at the border of the external penetration area(EPA)and the external unaff ected area(EUA)at the immersion ages of 3 and 7 d,and then it disappears gradually with immersion time.The WMS mortar can bind more external chloride,whereas the MS mortar can bind more internal chloride,at diff erent immersion times.The distributions of bound chloride conversion rate in the EPAs of the two types of mortars diff er across immersion times.The distribution fi rstly decreases,and then it increases at the immersion ages of 3 and 7 d.The distribution was from increase,then decreases,and increase again at the immersion ages of 28 and 56 d.The bound chloride conversion rate in the WMS mortar is aff ected more greatly by external chloride penetration than that in the MS mortar.The amounts of the Friedel’s salt tend to increase with prolonged immersion time.Finally,the penetration of external chloride can increase the amount of fi ne capillary pores smaller than 100 nm in the WMSmortar exposed for 56 d in the chloride salt solution(WMS-E)specimen.

H-M Bearing Capacity of A Modified Suction Caisson Determined by Using Load-/Displacement-Controlled Methods

This paper presents a series of monotonically combined lateral loading tests to investigate the bearing capacity of the MSCs （modified suction caissons） in the saturated marine fine sand. The lateral loads were applied under load- and displacement-controlled methods at the loading eccentricity ratios of 1.5, 2.0 and 2.5. Results show that, in the displacement-controlled test, the deflection-softening behavior of load-deflection curves for MSCs was observed, and the softening degree of the load-deflection response increased with the increasing external skirt length or the decreasing loading eccentricity. It was also found that the rotation center of the MSC at failure determined by the load-controlled method is slightly lower than that by the displacement-controlled method. The calculated MSC capacity based on the rotation center position in serviceability limit state is relatively conservative, compared with the calculated capacity based on the rotation center position in the ultimate limit state. In the limit state, the passive earth pressures opposite the loading direction under load- and displacement-controlled methods decrease by 46% and 74% corresponding to peak values, respectively; however, the passive earth pressures in the loading direction at failure only decrease by approximately 3% and 7%, compared with their peak values.