Investigation of the angle formed in irregular structures on their seismic behavior

The design of structures with re-entrant angle is often the consequence of the functional, architectural or urbanistic requirement. With any form building, the engineer has full responsibility to ensure the safety of the users and the structure in the case of the earthquake. However, re-entrant angle structures have geometric dissymmetry and limited choice in the disposition of rigid structural elements. The objective of this work is to evaluate the effect of the angle formed between the two wings of an L-shaped building, softened by a transition on their dynamic behavior. Different variants were considered by taking several angle values (45°, 60°, 75°, 90°, 105°, 120° and 135°). In order to evaluate the impact of the analyzed parameter, a study of the linear and non-linear dynamic behavior of the different structures was executed by the spectral modal analysis method and the non-linear static analysis. According to the atypical geometrical configuration in the plan of the various structures, six principal seismic directions were considered Ex, Ey, Ex’, Ey’, Ex” and Ey”. The results show that seismic excitation applied on the transition zone of a building with projected parts occurs a higher deformability. In addition, along this seismic direction, the progressive pushing of a uniform lateral loading applied on the structure with a projections opening angle of 90° assures a better nonlinear behavior in terms of base shears bearing capacity, deformation ductility and damage level

Effect of elevated temperature on the hydration heat and mechanical properties of blended cements mortars

This paper presents an experimental investigation for testing the effect of elevated temperature on the hydration heat and mechanical properties of blended cement mortars. Two tests on mortars were made. The first set of mortars is tested of mechanical properties at various temperatures of 20, 35 and 50°C and the second test consists to determine the hydration heat by a semi-adiabatic calorimeter at isothermal temperature of 20, 35 and 50°C during seven days. The new empirical equation has been proposed to estimate the compressive strength depending on the hydration heat for blended cement preserved in constant temperature at early. The results founded from this relationship illustrate a good accuracy with the experimental ones and reflect the best choice to be used to predict the compressive strength depending on the heat of hydration at early age (7 days)

Effect of elevated temperature on the hydration heat and mechanical properties of blended cements mortars

This paper presents an experimental investigation for testing the effect of elevated temperature on the hydration heat and mechanical properties of blended cement mortars. Two tests on mortars were made. The first set of mortars is tested of mechanical properties at various temperatures of 20, 35 and 50°C and the second test consists to determine the hydration heat by a semi-adiabatic calorimeter at isothermal temperature of 20, 35 and 50°C during seven days. The new empirical equation has been proposed to estimate the compressive strength depending on the hydration heat for blended cement preserved in constant temperature at early. The results founded from this relationship illustrate a good accuracy with the experimental ones and reflect the best choice to be used to predict the compressive strength depending on the heat of hydration at early age (7 days)

Parent Concrete Quality of Recycled Concrete Aggregates on Some Engineering Properties of Concrete

This paper aims to investigate some properties of recycled aggregates concrete (RAC) containing various amount of recycled concrete aggregates (RCA) supplied from different parent concrete strength. Three concretes with different strengths were made. After hardening, they were crushed and the obtained RCA were used to substitute 20%, 40% and 60% of coarse ordinary aggregates (COA) in concrete mix. The properties of these RCA according to their parent concrete strength were analyzed and their effects on the workability, compressive strength and shrinkage were quantified. Concrete workability and final shrinkage seem to be related to the equivalent water absorption of coarse recycled aggregates. An equivalent granular expression can be used in classical model to predict compressive strength according to the RCA content and its parent concrete strength.

Parent Concrete Quality of Recycled Concrete Aggregates on Some Engineering Properties of Concrete

This paper aims to investigate some properties of recycled aggregates concrete (RAC) containing various amount of recycled concrete aggregates (RCA) supplied from different parent concrete strength. Three concretes with different strengths were made. After hardening, they were crushed and the obtained RCA were used to substitute 20%, 40% and 60% of coarse ordinary aggregates (COA) in concrete mix. The properties of these RCA according to their parent concrete strength were analyzed and their effects on the workability, compressive strength and shrinkage were quantified. Concrete workability and final shrinkage seem to be related to the equivalent water absorption of coarse recycled aggregates. An equivalent granular expression can be used in classical model to predict compressive strength according to the RCA content and its parent concrete strength.

Effect of cement fineness and polycarboxylate dosage on the rheological and mechanical behavior of a mortar

The use of certain organic additives in the production of mortar and concrete influences the workability and the hydration kinetic of mortar. This results in a modification of some properties, namely rheological behavior and mechanical strength. The objective of this work is to evaluate the rheological and mechanical behavior of a mortar by varying the fineness of the cement and using the superplasticizer Polycarboxylate

Effect of cement fineness and polycarboxylate dosage on the rheological and mechanical behavior of a mortar

The use of certain organic additives in the production of mortar and concrete influences the workability and the hydration kinetic of mortar. This results in a modification of some properties, namely rheological behavior and mechanical strength. The objective of this work is to evaluate the rheological and mechanical behavior of a mortar by varying the fineness of the cement and using the superplasticizer Polycarboxylate

Beneficial Effect of Incorporation of Slag on the Hydration Heat, Mechanical Properties and Durability of Cement Containing Limestone Powder

This paper presents the experimental results of a wide research program, tending to determine the hydration mechanism, mechanical properties and the durability performance of ternary cement containing limestone powder and slag. The limestone powder increase the hydration at early ages inducing a high strength at, but it can reduce the later strength due to the dilution effect. On the other hands, Slag (S) contributes to increase the compressive strength at later ages. Hence, at medium blended cement (OPC-LP-S) with better performance could be produced. Results show at later age the Slag is very effective in producing ternary blended cements with similar on higher compressive strength than the ordinary Portland cement at 28 and 90 days. For durability, the incorporation of the slag into the cement containing limestone powder improves remarkably resistance to attack by acids and sulfates and it has been found that the durability of the cements never depends on the mechanical strength