International Concrete Abstracts Portal

This document is a guide for the design and construction of fixed reinforced and prestressed concrete structures for service in a marine environment. Only fixed structures that are founded on the seabed are covered. Contents include materials and durability; dead, deformation, live, environmental, and accidental loads; design and analysis; foundations; construction and installation; and inspection and repair. The two appendixes discuss environmental loads such as wave, wind, and ice loads in detail, and the design of offshore concrete structures for earthquake resistance. Keywords: concrete construction; cracking; dynamic loads; earthquakes; earthquake-resistant structures; floating; foundations; gravity-based structure(s); grouting; harbor structures; ice; inspection; marine; offshore structures; platform; post-tensioning; prestressed concrete; slipforming; underwater construction; waves.

This report provides information on the construction of structural concrete shells using an inflated form. Major facets of the construction process are covered, including foundations, inflation, monitoring, and backup systems. Other aspects, such as the geometric variations of inflated forms, thickness of polyurethane foam, and mixture proportions for shotcrete, are also considered. Keywords: dome; fabric; inflation; polyurethane foam; reinforcement; shotcrete; thin shell.

End hooks of steel fibers provide a stronger bridging force across the concrete matrix in steel fiber-reinforced concrete (SFRC). In this work, SFRC beams were prepared with steel fibers of the same length and diameter but different types of end hooks (straight, three-dimensional [3D], four-dimensional [4D], and fivedimensional [5D]) at increasing fiber volumes (0.0, 0.5, 1.0, 1.5, and 2.0%). Four-point bending tests conducted on each SFRC beam yielded load-deflection curves, from which the first cracking strength, flexural strength, and fracture toughness up to certain deflection-to-beam length ratios were obtained. The test results showed that the presence of end hooks remarkably enhanced the flexural strength and toughness of the SFRC beams, and this enhancement was amplified with an increasing number of hooks. Quantitative analysis revealed the hooking index, a factor introduced herein to delineate the efficiency of various types of hooks, was 1.00, 1.30, 1.60, and 2.10, respectively, for straight, 3D, 4D, and 5D steel fibers used in the present study. Lastly, empirical models for predicting flexural strength and toughness were established with high prediction accuracy.

This paper determines the effect of calcination temperature on the activity of polymerized aluminum chloride (PAC) waste residue. The effect of the calcination temperature of PAC waste residue on the compressive strength of cement mortar was studied using the slurry substitution method. The compressive strength data of cement mortar mixed with different temperatures of calcined PAC waste residue were analyzed by fitting. A compressive strength prediction model of PAC waste residue calcination temperature on the compressive strength of cement mortar can be built. The effect of PAC waste residue on the volume stability of cement mortar was also studied. The results showed that calcination increased the activity index of PAC waste residue by 5 to 10%, and 600°C was the optimal calcination temperature. Compared with the uncalcined PAC waste residue cement mortar, the calcined samples showed complete hydration, smaller micropores, and a denser overall structure. The fitting curve provided a good fit for the development of the compressive strength of cement mortar mixed with different temperatures of calcined PAC waste residue. A model of the calcination temperature of PAC waste residue on the compressive strength of cement mortar was derived based on the fitting curve. The volume stability of cement mortar mixed with PAC waste residue calcined at 600°C was improved.

To make full use of recycled aggregate concrete (RAC), carbon fiber (CF) and nano-metakaolin (NMK) were mixed into RAC to improve its mechanical properties and microstructure. The effects of NMK content, CF content, recycled aggregate (RA) replacement rate, and CF length on the compressive strength, splitting tensile strength, and tension-compression ratio of RAC were studied by the orthogonal test method; then, the test results were analyzed. The results show that the NMK content and RA replacement rate have significant effects on the compressive strength of RAC, while the CF content has significant effects on the splitting tensile strength and the tension-compression ratio. Through the synergistic effect of NMK and CF, the pore structure characteristics of RAC are improved, and the bond strength of the interfacial transition zone (ITZ) of CF-mortar is increased, which further enhances the strengthening effect of CF; thus, the mechanical properties of RAC are continuously enhanced.