A study on carbonation depth prediction for fly ash concrete

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Climate change impact and risks of concrete infrastructure deterioration

Permeability Characteristics of Carbonated Concrete Considering Capillary Pore Structure

Durability of alkali-activated materials in aggressive environments: A review on recent studies

Utilisation of Bayer's process bauxite residue, BR, aka red mud, takes place in a very small fraction worldwide, most probably

Bauxite residue in cement and cementitious applications: Current status and a possible way forward

The behaviour and ultimate load capacity of laterally-restrained reinforced concrete slabs can be considerably enhanced by the development of arching or compressive membrane action. This paper presents a simple method for predicting the enhanced ultimate load capacity of laterally-restrained slab strips. The method is based on deformation theory and utilizes an elastic-plastic stress-strain criterion for concrete. The loads carried by bending and arching action are calculated separately and then added to give the total ultimate load capacity. A simple equivalent strip approach, based on a three-hinged arch analogy, allows for the degree of lateral restraint. The method of prediction has been validated by correlation with a wide range of test results from various sources. (A)

Arching action strength enhancement in laterally-restrained slab strips

The effect of relative humidity on both air permeability and rate of carbonation is investigated. Descriptive models, based on data from an accelerated carbonation test, were developed to quantify the effects of the relative humidity and the air permeability on the rate of carbonation. The relationships between the rate of carbonation and physical properties, such as the permeation properties and compressive strength were established. It was found that the permeation measurements should only be used to estimate the likely rate of carbonation when the relative humidity of the concrete specimen is known.

Effect of relative humidity and air permeability on prediction of the rate of carbonation of concrete

The corrosion of reinforcement in bridge deck slabs has been the cause of major deterioration and high costs in repair and maintenance. This problem could be overcome by reducing the amount of reinforcement and/or altering the location. This is possible because, in addition to the strength provided by the reinforcement, bridge deck slabs have an inherent strength due to the in-plane arching forces set up as a result of restraint provided by the slab boundary conditions. This is known as arching action or Compressive Membrane Action (CMA). It has been recognised for some time that laterally restrained slabs exhibit strengths far in excess of those predicted by most design codes but the phenomenon has not been recognised by the majority of bridge design engineers. This paper presents the results of laboratory tests on fifteen reinforced concrete slab strips typical of a bridge deck slab and compares them to predicted strengths using the current codes and CMA theory. The tests showed that the strength of lat...

Arching action in high strength concrete slabs

A combined experimental and analytical investigation into the effects of arching action on the ultimate strength of reinforced concrete rectangular and Tee beams is presented in this paper. An existing flexural method for rectangular section slab strips is first extended for Tee beams. This is then combined with a rational method for the prediction of the shear strength of beams, developed previously by the authors. The resulting integrated procedure is used to predict the enhanced ultimate flexural and shear capacities of longitudinally restrained rectangular beams and Tee beams. To validate the new procedure, a complementary programme of tests on scaled models was carried out. The results of these tests, together with those of other authors, were analysed. The proposed method is shown to be more accurate and consistent than the current British and American code procedures, which do not currently allow for strength enhancement due to arching action. The method is also shown to give better correlation wit...

Arching action - flexural and shear strength enhancements in rectangular and Tee beams

Deterioration of bridge deck slabs due to corrosion of reinforcement has become increasingly evident over the past 40 years and continues to be the cause of costly repair programmes. Detailing to reduce the risk of corrosion is simpler if the percentage of reinforcement is low. It is now recognised that laterally restrained slabs exhibit strengths far in excess of those predicted by most design codes. This increase in strength can be attributed to arching or compressive membrane action (CMA), and by recognising it in design, lower percentages of reinforcement can be specified. CMA has been incorporated into a small number of design standards. However, problems still exist in translating the arching theory into slabs in practice. The problem is in the assessment of the degree of external lateral restraint inherent in slab structures. This paper presents the results of tests on eight one-third-scale bridge deck edge panel models with target compressive strengths of 100 N/mm2. The test programme aimed at rea...

G. I. B. Rankin

Papers

Arching action strength enhancement in laterally-restrained slab strips

Effect of relative humidity and air permeability on prediction of the rate of carbonation of concrete

Arching action in high strength concrete slabs

Arching action - flexural and shear strength enhancements in rectangular and Tee beams

Real strength of high performance concrete bridge deck slabs