At the early maturity stage, the curing temperature has a significant impact on the mechanical properties of concrete. Concrete cubes are cured in water baths at different temperatures—5 °C, 20 °C, 35 °C, and 50 °C—in order to measure their compressive strength. This method is predicated on the knowledge that the pace of cement hydration is strongly influenced by the curing temperature. Then, the realistic curing temperature regime was imposed where the temperature of the curing water was modified based on the temperature patterns obtained from semi-adiabatic testing of concrete mixes to simulate curing conditions in the core of massive concrete structures. Ordinary Concrete: Compared to specimens cured at an isothermal curing at 20 °C, those cured in water baths at realistic curing showed an increase in compressive strength of 48% at seven days and 18.5% at 28 days. Fly Ash 18% Replacement: Compared to specimens cured at at 20 °C, the compressive strength of those cured at realistic curing increased by 45% at seven days, with a modest rise of 0.2% by the 28th day. Slag 18% Replacement: Compared to specimens cured at 20 °C, the compressive strength of those cured at realistic curing increased significantly by 121% at seven days and by 21.7% at 28 days.

As emission regulations in the EU are becoming stricter, the reduction of greenhouse gas emissions from the construction industry has become a pressing need. As part of the efforts related to this issue, it has been found that Environmental Life Cycle Analysis (LCA) approaches are required to optimize the design, construction, operation, and maintenance of buildings and infrastructure assets. In this paper, The Institution of Structural Engineers guidance on how to calculate the embodied carbon in structures is used as LCA model and evaluated in a case study. The guidance divides the structure´s life cycle into five stages (A1-A3: Product, A4-A5: Construction process, B1-B7: Use, C1-C4: End of live and D: Benefits and loads beyond the system boundary) and the environmental impact is measured in terms of carbon dioxide equivalent emissions (kgCo2e) or global warming potential (GWP). The model was applied to an existing reinforced concrete trough bridge, which is a structure type commonly used in Swedish railways. Results show that that the model was effective and simple for investigating the environmental impact of the studied structure. 

Concrete cracks in structures such as water tanks and nuclear power stations cause anxiety to owners, contractors and engineers. These cracks may significantly increase the structure’s permeability and thus increase leakage, reduce durability, and eventually lead to loss of structural functionality. Therefore it is important to minimize their occurrence and size. To identify effective ways of minimizing cracking in young concrete segments, a parametric study was conducted using the finite element method (FEM). Parameters considered include casting sequence, joint position, wall height, and cooling. The study examined continuous and jumped casting approaches to the casting of a cylindrical reinforced concrete tank for a sewage-treatment plant, with and without the application of the ‘kicker’ technique in which the lower part of the wall is cast with the slab. The main cause of cracking is thermal change and restraint imposed by adjacent older structures, and the FEM predictions agree well with experimental observations. Continuous casting is most effective at minimizing cracking because it creates only two contact edges between newly cast and existing structures producing the lowest level of restraint. The kicker technique is shown to be very effective for reducing restraint and consider rephasing.

Nowadays, prefabricated concrete components made from Steel-Fiber-Reinforced Concrete (SFRC) are widely used in the construction industry. These components are often connected to existing or new structural elements through various fastening systems. Previous studies have shown that the addition of steel fibers to concrete mixture substantially improves the fracture properties of concrete. To date, however, rather limited research is available on the behavior of fastening systems in SFRC. To improve the current knowledge of fastening systems to SFRC structures, a pilot experimental study is carried out on cast-in-place anchor bolts embedded in Plain Concrete (PC) and SFRC members. In this study, the influence of the presence of steel fibers and concrete compressive strength on the anchorage capacity and performance is evaluated. Furthermore, the applicability of current design methods is evaluated for anchorage systems in SFRC.

In numerical assessments of concrete bridges, the value of the concrete fracture energy GF plays an important role. However, mostly the fracture energy is only estimated based on the concrete compressive strength using empirical formulae. In order to study methods to determine the concrete fracture energy for existing bridges, tests were carried out on 55-year-old concrete from a bridge tested to failure in Kiruna in northern Sweden. Uniaxial tensile tests are performed on notched cylindrical concrete cores drilled out from this and other bridges. In the paper, different methods to determine the concrete fracture energy are discussed and recommendations are given for assessment procedures.

Bonded concrete overlays (BCO) on bridge decks are beneficial solutions due to their superior properties as compared to the typical asphalt pavement. A significant number of overlays suffer however, from occurrence of cracks and delamination due to poor bond, and restrained shrinkage and thermal dilation. Over the past years different appraisals for estimation of the restrained deformations have been developed, from micro-scale models, based on poromechanics, to empirical equations as given in B3 or B4 models suggested by Baiant. This paper provides a short overview of calculation models along with a brief theoretical explanation of shrinkage mechanism.

The concrete arch bridge over Kalix River at Långforsen was built in 1960 and has a mid-span of 89,5 m and a height of 13,7 m. The bridge owner, Trafikverket, wanted to increase its allowable axle load from 225 to 300 kN. Field tests were carried out under service condition and with ambient vibrations. The test results were used to update and validate Finite Element Models. At last, the refined models were used to check the possibility to increase the axle load.

According to earlier assessments, most parts of the bridge is capable of carrying an axle load of 330 kN. The only critical sections are located in the beams carrying the rail on top of the arch in the section where the beams are united with the arch. Here the stresses in the longitudinal bottom reinforcement are slightly too high.

These sections have been studied in a FEM model for different loads and results show maximum strains of about 50·10^-6 corresponding to stresses of only about 10 MPa in the reinforcement in the critical sections. Live load vertical deflections of the crown of the arch is of the order of only ± 6 mm. Dynamic studies have also been made showing that fatigue is no issue. Altogether the studies show that the bridge is able to carry an increased axle load of 300 kN without problems.