Performance enhancement of recycled concrete aggregate – A review

Mechanical and durability properties of high-strength concrete containing steel and polypropylene fibers

Supplementary cementing materials in concrete: Part I: efficiency and design

Influence of pozzolan from various by-product materials on mechanical properties of high-strength concrete

In recent years, an emerging technology termed, “High-Performance Fiber-Reinforced Concrete (HPFRC)” has become popular in the construction industry. The materials used in HPFRC depend on the desired characteristics and the availability of suitable local economic alternative materials. Concrete is a common building material, generally weak in tension, often ridden with cracks due to plastic and drying shrinkage. The introduction of short discrete fibers into the concrete can be used to counteract and prevent the propagation of cracks. Despite an increase in interest to use HPFRC in concrete structures, some doubts still remain regarding the effect of fibers on the properties of concrete. This paper presents the most comprehensive review to date on the mechanical, physical, and durability-related features of concrete. Specifically, this literature review aims to provide a comprehensive review of the mechanism of crack formation and propagation, compressive strength, modulus of elasticity, stress–strain behavior, tensile strength (TS), flexural strength, drying shrinkage, creep, electrical resistance, and chloride migration resistance of HPFRC. In general, the addition of fibers in high-performance concrete has been proven to improve the mechanical properties of concrete, particularly the TS, flexural strength, and ductility performance. Furthermore, incorporation of fibers in concrete results in reductions in the shrinkage and creep deformations of concrete. However, it has been shown that fibers may also have negative effects on some properties of concrete, such as the workability, which get reduced with the addition of steel fibers. The addition of fibers, particularly steel fibers, due to their conductivity leads to a significant reduction in the electrical resistivity of the concrete, and it also results in some reduction in the chloride penetration resistance of the concrete.

High-performance fiber-reinforced concrete: a review

Various combinations of a local natural pozzolan and silica fume were used to produce workable high to very high strength mortars and concretes with a compressive strength in the range of 69–110 MPa. The mixtures were tested for workability, density, compressive strength, splitting tensile strength, and modulus of elasticity. The results of this study suggest that certain natural pozzolan–silica fume combinations can improve the compressive and splitting tensile strengths, workability, and elastic modulus of concretes, more than natural pozzolan and silica fume alone. Furthermore, the use of silica fume at 15% of the weight of cement was able to produce relatively the highest strength increase in the presence of about 15% pozzolan than without pozzolan. This study recommends the use of natural pozzolan in combination with silica fume in the production of high strength concrete, and for providing technical and economical advantages in specific local uses in the concrete industry.

High strength concrete containing natural pozzolan and silica fume

Characteristics of lightweight concrete containing mineral admixtures

A series of 10 one-third scale square reinforced concrete column specimens were cast; preloaded under axial compression up to various fractions (0%, 60%, 80%, and 100%) of its ultimate load; repaired using ferrocement jackets containing two layers of Welded Wire Mesh (WWM) encapsulated in high strength mortar; and then retested to failure. The overall response of the specimens was investigated in terms of load carrying capacity, axial displacement, axial stress and strain, lateral displacement, and ductility. The test results indicated that jacketing reinforced concrete square columns with this form of ferrocement provided about 33% and 26% increases in axial load capacity and axial stiffness, respectively, compared to the control columns. The test results also indicated that repairing similar reinforced concrete columns (after preloading them to failure) with the same ferrocement jacket almost restored their original load capacity and stiffness. Furthermore, the repaired columns failed in a ductile manner compared to the brittle failure exhibited by the control columns.

Repair and strengthening of reinforced concrete square columns using ferrocement jackets

High-performance concrete mixes containing various proportions of natural pozzolan and silica fume (up to 15% by weight of cement) were prepared and stored in sodium and magnesium sulfate solutions, in Dead Sea and Red Sea waters. The progressive deterioration and the relative sulfate resistance of these mixes were evaluated through visual observations, ultrasonic pulse velocity measurements, and relative strength determinations. The investigation indicated that the concrete mix containing 15% natural pozzolan, and 15% silica fume showed the best protection in sulfates solutions and sea waters. It retained more than 65% of its strength after one year of storage in sulfates solutions and sea waters. The superior resistance of that mix against sulfate attack is attributed to the pore refinement process and further densification of the transition zone occurring due to the conversion of lime forming from the hydration of cement into additional binding material through lime-pozzolan reaction. This investigation recommends the use of silica fume in combination with natural pozzolan for better performance in severe sulfate environments.

M.J. Shannag

Papers

High strength concrete containing natural pozzolan and silica fume

Characteristics of lightweight concrete containing mineral admixtures

Repair and strengthening of reinforced concrete square columns using ferrocement jackets

Sulfate resistance of high-performance concrete

Flowable high strength cementitious matrices for ferrocement applications