Effect of silica fume on carbonation of reinforced concrete structures in Persian Gulf region

2010 ◽  
pp. 1488-1493
Keyword(s):  
Reinforced Concrete ◽  
Silica Fume ◽  
Persian Gulf ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Gulf Region

Effect of Different Curing Regimes on Shrinkage and Strength Properties of Self-Consolidating Mortars Containing Silica Fume in Different Contents

2013 ◽  
Vol 357-360 ◽  
pp. 1271-1276 ◽  
Author(s):  
Jamshid Esmaeili ◽  
Jamil Kasaei
Keyword(s):  
Reinforced Concrete ◽  
Silica Fume ◽  
Concrete Structures ◽  
Cementitious Materials ◽  
Strength Properties ◽  
Reinforced Concrete Structures ◽  
Architectural Elements ◽  
Curing Methods ◽  
Water Curing ◽  
Curing Regimes

The aim of this research is to study the effect of different curing regimes on shrinkage and strength properties of self-consolidating mortars (SCM) containing silica fume in different contents. Self-consolidating mortars, as new technology products, are especially preferred for use in architectural elements and the rehabilitation and repair of reinforced concrete structures. SCM can be used in precast architectural elements or cast in place repair of reinforced concrete structures. Therefore, investigation on the effects of different curing methods on key properties of SCMs can be beneficial. The shrinkage and strength properties of SCMs produced at different replacement ratios of silica fume (SF) with cement in different curing regimes were studied, at this paper. SCM mixes were prepared in constant water/powder ratio and cured in four different regimes including water curing (WC), accelerated water curing (AWC), air curing (AC) and aluminum tape sealing (AS). A polycarboxylate-based superplasticizer (SP) was added to the mixtures at different rates by mass of the cementitious materials to have appropriate flowability. Fresh mortars workability was determined using mini slump flow and mini V-funnel tests. All SCM specimens were tested and evaluated for compressive strength, flexural strength and shrinkage. It has been found that different curing regimes have considerable effects on both shrinkage and strength properties of SCM. It can be concluded that aluminum tape sealing and accelerated water curing can be used as effective and successful curing methods particularly where the SCM is used as a repair material or in architectural elements, respectively.

Design of precast reinforced concrete structures of frame buildings: a new set of rules

2019 ◽  
pp. 4-9 ◽  
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Building Frames ◽  
Fine Grained ◽  
Rigid Frame ◽  
Floor Slabs ◽  
Frame Buildings ◽  
Spatial System ◽  
Precast Elements

Currently, prefabricated reinforced concrete structures are widely used for the construction of buildings of various functional purposes. In this regard, has been developed SP 356.1325800.2017 "Frame Reinforced Concrete Prefabricated Structures of Multi-Storey Buildings. Design Rules", which establishes requirements for the calculation and design of precast reinforced concrete structures of frame buildings of heavy, fine-grained and lightweight structural concrete for buildings with a height of not more than 75 m. The structure of the set of rules consists of eight sections and one annex. The document reviewed covers the design of multi-story framed beam structural systems, the elements of which are connected in a spatial system with rigid (partially compliant) or hinged joints and concreting of the joints between the surfaces of the abutting precast elements. The classification of structural schemes of building frames, which according to the method of accommodation of horizontal loads are divided into bracing, rigid frame bracing and framework, is presented. The list of structural elements, such as foundations, columns, crossbars, ribbed and hollow floor slabs and coatings, stiffness elements and external enclosing structures is given; detailed instructions for their design are provided. The scope of the developed set of rules includes all natural and climatic zones of the Russian Federation, except seismic areas with 7 or more points, as well as permafrost zones.

Improvement Of Curvilinear Diagrams Of Concrete Deformation

2019 ◽  
pp. 99-104
Keyword(s):  
Reinforced Concrete ◽  
Peak Load ◽  
Experimental Studies ◽  
Concrete Structures ◽  
Deformation Model ◽  
Reinforced Concrete Structures ◽  
Significant Difference ◽  
Deformation Diagrams

Problems when calculating reinforced concrete structures based on the concrete deformation under compression diagram, which is presented both in Russian and foreign regulatory documents on the design of concrete and reinforced concrete structures are considered. The correctness of their compliance for all classes of concrete remains very approximate, especially a significant difference occurs when using Euronorm due to the different shape and sizes of the samples. At present, there are no methodical recommendations for determining the ultimate relative deformations of concrete under axial compression and the construction of curvilinear deformation diagrams, which leads to limited experimental data and, as a result, does not make it possible to enter more detailed ultimate strain values into domestic standards. The results of experimental studies to determine the ultimate relative deformations of concrete under compression for different classes of concrete, which allowed to make analytical dependences for the evaluation of the ultimate relative deformations and description of curvilinear deformation diagrams, are presented. The article discusses various options for using the deformation model to assess the stress-strain state of the structure, it is concluded that it is necessary to use not only the finite values of the ultimate deformations, but also their intermediate values. This requires reliable diagrams "s–e” for all classes of concrete. The difficulties of measuring deformations in concrete subjected to peak load, corresponding to the prismatic strength, as well as main cracks that appeared under conditions of long-term step loading are highlighted. Variants of more accurate measurements are proposed. Development and implementation of the new standard GOST "Concretes. Methods for determination of complete diagrams" on the basis of the developed method for obtaining complete diagrams of concrete deformation under compression for the evaluation of ultimate deformability of concrete under compression are necessary.

Sign in / Sign up

Export Citation Format

Share Document