The Effects Of Self Compacting Self Cured Concrete By Changing The Steel Fiber Content

Aggregate is one of the basic constituents of concrete. Its quality is of considerable importance because about three-quarter of the volume of concrete is occupied by aggregates. One of the physical properties of aggregate that influence the property of concrete is the grading of aggregate. The grading of aggregate defines the proportions of particles of different size in the aggregate. The grading of fine (size < 5 mm) and coarse (size > 5 mm) aggregates are generally required to be within the limits specified in BS 882: 1992.

HSC offers many advantages over conventional concrete. The high compressive strength can be advantageously used in compression members like columns and piles. Higher compressive strength of concrete results reduction in column size and increases available floor space. HSC can also be effectively used in structures such as domes, folded plates, shells and arches where large in-plane compressive stresses exist. The relatively higher compressive strength per unit volume, per unit weight will also reduce the overall dead load on foundation of a structure with HSC.

Ultra high performance concrete (UHPC) represents a major progress step over normal strength concrete (NSC) and high strength concrete (HSC), through the achievement of very high strength and very low permeability. Basically, the UHPC is a concrete with compressive strength ranging 120 to 400 MPa, this “ultra” high strength is achieved through different techniques including the use of improved materials, ultra-fine pozzolans (e.g. silica fume), low water-cement ratio, improved quality and higher dosage of superplasticizer, use of fibers (metallic or synthetic) to increase the energy absorption capacity and decrease brittleness, high cementitious materials content, longer mixing time and heat treatment [1]. UHPC tensile strength varies from 10 to 30 MPa; and the modulus of elasticity is in the range of 60 – 100 GPa [2].

In 2005, H Azamirad et al published a paper “A criticism of Self-Compacting Concrete” which talks about the problems in using SCC such as segregation and roles of different materials which affect it. It talks about the economic problems too. Finally it says about some projects which are executed with SCC. This paper helped in identifying the disadvantages of using SCC.

Reinforced concrete is one of the most important available materials for construction in Egypt and all over the world. It is used in almost all structures as: buildings, shells, bridges, tunnels, tanks and retaining walls. Concrete is made by mixing binding materials as sand and gravel held together with a paste of cement and water. The used of admixture is to change certain characteristic of concrete such as workability, durability and time of hardening. Some of concrete advantages are its high compressive strength, its ability to cast in almost any desired shape, its economical and fire resistance. Low tensile strength, low ductility and cracking consider one of its disadvantages. Regardless of this disadvantages,

Roller-compacted concrete (RCC) is a stiff mixture of aggregates, cementitious materials, and water with zero slump. RCC is consolidated or compacted in the fresh state by use of a roller with or without vibration. RCC typically is placed with asphalt paving equipment in thicknesses of 4 to 8 inches for pavement application. RCC has gained the attention of the paving industry in recent years and is becoming more popular day by day because of its low cost, rapid construction, and durable performance. The energy required to compact RCC mixtures to their maximum densities is much greater than for concrete of measurable slump. The largest difference between RCC mixtures and conventional concrete mixtures is that RCC has a higher percentage of fine

Concrete is one of the essential component of public infrastructure and most buildings. It can only be more effective if we used reinforcement with it, because tensile strength without reinforcement is very low. It usually get cracked with time as it is brittle in property. There are some more causes of these cracks are shrinkage, inadequate water for hydration… etc. these cracks causes reinforcement exposes to atmosphere now reinforcement come into contact of O2 & H2O. That can cause corrosion which results in weaken of structure. That being said concrete is a high maintenance material. Concrete cracks and suffer wear and tear. Concrete is not as much flexible that it can handle significant amount of strain.

High-performance concrete (HPC) is defined as a concrete meeting special combination of performance and uniformity requirements that cannot always be achieved routinely using conventional constituents and normal mixing, placing, and curing practices. What’s more HPC is a relatively new concrete terms that are used, it is consistent to those of the most common applications in more than one set of standards, but not limited to strength.

The report will mainly focus on the differences between reinforced, prestressed and partially stressed concrete. These concrete reinforcing methods differ in the period they have been used. Reinforced concrete was developed by a nursery owner in Paris in 1867, Joseph Monier, applying it to practical use for the first time (Salmon & Wang, 2007). Prestressed concrete’s discovery dates back to the late 1800’s. Freyssinet was one of the first engineers who used this method and realised that, for this method, high quality concrete with very high tensile steel wires, stressed as high as possible was needed (Chris Burgoyne, 2005).

There is a strong correlation between the compressive strength and other mechanical properties of concrete (Neville, 1996, Mehta and Monterio, 2005). Compressive strength is used as an index of flexural strength, tensile strength and shear strength of concrete. The flexure strength or modulus of rupture of normal concrete is approximately 7.5 to 10 times the square root of the compressive strength. Similarly, the tensile strength is about 8 to 12% of the compressive strength and is often estimated as 5 to 7.5 times the square root of the compressive strength. The shear strength of concrete is about 20% of the compressive strength (PCA, 1988). These correlations between compressive strength and flexure, tensile and shear strength varies with concrete ingredients and environment.

Over the past quarter century, the number of both experimental and analytical studies have increased dramatically on the monotonic axial behavior of FRP-confined concrete columns, and as a result, many uniaxial stress-strain models have been generally developed; however, most of these studies have focused largely on FRP-confined circular plain (unreinforced) concrete cylinders numerous authors tested (e.g., Mirmiran and Shahawy 1997;Mirmiran et al.1998; Xiao and Wu 2000; Lam and Teng 2002,2003;Berthet et al.2005;Almusallam 2007; Benzaid et al.2008;Eid and Paultre 2007,2008;Teng et al. 2009;Smith et al. 2010;Cui et al.2010). Relatively few of which have included small or medium scale noncircular unreinforced specimens

This literature review provides the necessary information on concrete technology in general with emphasis laid on the materials used for its production. The basic engineering properties of both TVC and SCC are looked at and a comparison of their mix proportions is done. The mixture proportioning and acceptance criteria for SCC is presented with a brief description of the evaluation methods used.

The conventional cast in-suit concrete is done usually repair and strengthing works in the cases where due to the change in volume or shrinkage of the convection cement based concrete, causing unsatisfactory results. The change in volume results in loss of good contact between the new concrete and the old element preventing sound transfer of stress at the contact surface. In order to improve bond characteristics and minimize the shrinkage, it is recommended to use higher strength concrete with low

Concrete as is well known is a heterogeneous mix of cement, water and aggregates. The admixtures may be added in concrete in order to enhance some of the properties desired specially. In its simplest form, concrete is a mixture of paste and aggregates. Various materials are added such as fly ash, rice husk, and admixture to obtain concrete of desired property. The character of the concrete is determined by quality of the paste. The key to achieving a strong, durable concrete rests in the careful proportioning, mixing and compacting of the ingredients.

Abstract- This study concerns the investigation of concrete produced by partial replacement of cement with corn cob ash (CCA). Corn cob ash was obtained and used to replace cement partially in specified ratios of 5%, 10%, 15%, 20% and 25%. Concrete cubes were cast and cured in ages of 7, 14 and 28 days respectively. While concrete beams were cast and cured for 28 days. Compressive strength test was carried out on the cubes and the flexural strength on beam. The results showed that the concrete strength decreased with increasing replacement with the corn cob ash (CCA). The 28 days compressive strength for 5% replacement was 28.78N/mm2, 10% replacement was 26.22N/mm2, 15 % replacement was 22.33N/mm2, 20% replacement was 20.27N/mm2 and 25% replacement was 17.33N/mm2 respectively while its flexural strength for same age for 5% replacement was 9.98N/mm2, 10% replacement was 8.58N/mm2, 15% replacement was 7.82N/mm2, 20% replacement was 6.56N/mm2 and 25% replacement was 5.72N/mm2. The initial and final setting time of OPC-CCA at 10% replacement was observed to be 168minutes and 305minutes respectively. The density of OPC-CCA was also observed to decrease with increasing CCA replacement. The 28 day density for 10% CCA replacement for