Curious Civil Engineer

  Glass fiber-reinforced polymer (GFRP) reinforcement has emerged as a new opponent to conventional reinforcement. The GFRP owns a higher tensile strength, non-corrosive reinforcement, lighter weight, and higher strength-weight ratio. The corrosion of reinforcement can severely damage the structure by causing the concrete to cracks or spall. The Maintainance of damaged structures can significantly be costly. The GFRP is a non-corrosive reinforcement. Therefore, the use of GFRP can eliminate the deterioration of structure due to reinforcement corrosion. The use of GFRP has increased recently for many applications such as bridge deck, pavement, walls, and other applications. However, the use of GFRP is limited due to the lack of information about the long-term performance of GFRP. Figure 1 GRFP bars have many advantages, such as tensile strength. The tensile strength of GRFP bars is higher than the conventional reinforcement. Table no:1 shows the mechanical properties of GRFP bars. We ca

  TMT bars are thermally mechanically treated steel bars with high strength and good mechanical properties compared to mild steel bars. TMT bar is a new enhanced version of mild steel bars. The treatment process of TMT bars includes 3 stages: quenching, self tempering, and atmospheric cooling. The quality of produced TMT bars depends on the quality of raw materials, quality of rolling mill, and quality of quenching and tempering process.  Figure 1 The process of manufacturing steel is divided into two stages. The first stage is molten iron production. In this stage, iron-sand and coal are heated in a multi-hearth furnace—heating the raw materials done in stages. First, the furnace pre-heat the material to reduce the volatile matter present in coal from 44% to 9%. There are 12 hearths in each furnace. The mixture temperature will be increased gradually through these hearths. Finally, the temperature will be adjusted to 620 C.  Figure 1 The output after removal of the impurities introduc

 Ductility is an important property of steel reinforcement. Ductility is the ability of the material to undergo plastic deformation before failure. The ductility of reinforcement is related to the elongation property. The ductility of reinforcement ensures safer and durable structures. Material that undergoes little or no plastic deformation is known as a brittle material. Brittle reinforcement can cause sudden structure failure because it doesn't undergo any plastic deformation before failure.  Figure 1 The ductility factor for reinforcement can be computed using the following equation: µ=ϵu/ϵy where, µ is the ductility factor ϵu is the ultimate strain ϵy is the yield strain In figure no:1-a, we can see the stress-strain curve for mild steel. The mild steel has well-defined yield stress and strain, as shown in the stress-strain curve. The reinforcing bar can recover all the elongation if the applied stress is lesser than the yield stress. This portion of the curve is known as the

 Construction management: Road construction course This course is designed to expand your practical side of engineering knowledge. This course is concentrating on the construction of roads. Here you will learn how the road is constructed. The construction stages such as protection of existing services, clearing the area, future utilities, preparing the road subgrade, then placing different pavement layers such as sub-base, base course, and asphaltic courses. We will also discuss the types of asphaltic course and the common defects of asphaltic pavement, such as permanent deformation, fatigue cracking, and low-temperature cracking. Also, I will show a typical cross-section of road and road profiles and many other subjects. Enroll from here  Pile foundation design This course will discuss the design of pile foundations. We will learn the methods of calculating the pile bearing capacity. The bearing capacity for a pile consists of skin and end bearing resistance. Here you will understand

 Corrosion of steel reinforcement is problematic and posing a threat to reinforced concrete structures. Severe corrosion of reinforcement can result in concrete spalling and damaging structure integrity. Various factors can affect the rate of reinforcement corrosions. The environment is one of these factors. For example, the rate of reinforcement corrosion will accelerate for structures submerged in seawater compared to structures built above the ground—concrete properties playing an important role in reducing the rate of reinforcement corrosion. Concrete with low permeability will reduce the ingress of chemicals that cause the corrosion of reinforcement, which can effectively slow the corrosion of reinforcement. The concrete cover is another factor that can effectively slow reinforcement corrosion. Usually, a higher concrete cover is used for members of the structure in contact with groundwater or soil. Figure 1 In a severe environment, galvanized reinforcement can be used to reduce

  Cofferdams are temporary structures used as a barrier to keep out the water and soil during the construction of a permanent structure such as a foundation in a maritime environment. The loads imposed on cofferdams structure includes hydrostatic forces of the water and dynamic forces due to waves and currents. The construction of cofferdams is a tough job since it is usually constructed offshore and in severe weather conditions. Therefore, the tolerance of construction may deviate from the design due to construction conditions, and cofferdams elements may deform significantly during cofferdam construction.  Figure 1 For a typical cofferdam, the construction sequence will be as follow. The construction of the cofferdam will begin with the preparation of the cofferdam area. The soil and sediments will be removed, and the area will be leveled.  The temporary support piles will be driven, and temporary supporting frames will be erected on support piles.   Figure 2 Drive the sheet pile to

The methods of repairing concrete cracks are dependant on crack types. We have two types of cracks: dead and live crack. The concrete cracks that are stagnant and not growing, known as dead cracks. While if the cracks growing in size, it is known as live cracks. The repairing of dead cracks is easier. Once the dead cracks are appropriately repaired, there is a lower chance that the concrete will crack again. Concrete cracks can reduce the durability of the structure. Cracks will work as a passage of harmful chemicals such as chloride. The ingress of chloride will accelerate the corrosion of reinforcement, and this can cause concrete spalling and excessive cracking of concrete.   Figure 1  Dead cracks are caused by a previous event such as concrete shrinkage or accidental overloading of the structure. Cracks wider than 1 mm can be sealed by filling them with cement grout. For finer cracks or those in the soffit or vertical surfaces, Polymer can be used to seal them. Epoxy resin or polye

  Concrete bonding agent used for bonding fresh concrete to existing hardened concrete. the bonding agents can be used for existing horizontal or vertical concrete surfaces where the fresh concrete will be supported by formworks. the bonding agent can be used at construction joint locations to ensure better adhesion between old and new concrete. in large structures such as bridge deck. the casting of the whole deck at one time is difficult and not practical. therefore, the deck divided into areas and each area casted separately.  Figure 1 before applying the bonding agent, the existing concrete surface should be cleaned properly. all grease, loose concrete, plaster, oil, or any other dirt should be removed. furthermore, the surface of the concrete should be roughened by scrabbling or grit blasting. The mixing and applying of bonding should be as per the manufacturer. the component of the bonding agent should be mixed properly. the bonding agent should be applied thoroughly on the exist

Fatigue is an interesting phenomenon. Fatigue is a condition in which the material cracks and fails due to cyclic loading under the ultimate strength of the material. In fatigue, the materials are not loaded to their limit. However, the materials fail, and the reason behind failure is the repeated cycles of loads. Fatigue often occurs suddenly, and it can result in catastrophic consequences.    Figure 1 When a material is loaded, a crack will be initiated or nucleated in the materials. The continuous cyclic loading of the material will result in growing the crack size. Finally, when the crack is large enough, the material will fail. The phenomenon of fatigue can't be studied from the engineering side only. We should also study the properties of the material thoroughly.  The figure below showing the phases of fatigue failure. At the beginning stage, the crack start as a slip band in material grains. The slip band will result in forming slip steps; in the presence of oxygen, the fres

Large structures are usually poured in different stages. It is not possible to cast large structures at one time. The casting of large structures at one time will require a long time, a huge number of workers and equipment. In some cases, the geometric and sequence of work will require the casting of a structure in several stages. Pouring of concrete will result in forming construction joints between different concrete pours. Water-stop is usually used for various structures such as dams, water treatment facilities, storage tanks, culvert, slab on grade, and parking garage. The use of water-stop for storage tanks is critical. Water-stop will prevent the liquid from leaking. So, in general, water-stop will be used for structures that in direct contact with water. Water-stop will prevent the seepage of water from the construction joint. We have two types of water-stop. External water-stop fixed on the wet side of a concrete structure, as shown in figure no:2. External water-stop will pr

Tremie pipe can be defined as segments of steel pipe. These segments will be connected together and used to cast a drilled pile foundation. Using of tremie pipe will prevent the segregation of concrete. Tremie pipe will ensure that the concrete is not thrown from a huge height. As we know, placing the concrete from any distance higher than 1.5 m can cause concrete segregation. Therefore, tremie pipes are used. The tremie pipe segment will be connected to a length equal to pile length. Then it will be lowered to the bottom of the pile hole. Figure no:1 shows a tremie pipe inserted inside the casing and steel cage of a pile before beginning with the concerting of the pile.  Figure 1 We should always ensure that the tremie pipe external diameter is suitable. We should ensure that the tremie pipe doesn't clash with the steel cage or any spacer blocks. Also, we should make sure that the internal diameter of the tremie pipe is sufficiently bigger than the maximum size of concrete aggrega

Anchors can be installed for various reasons. Anchors can be conventional reinforcing bars or bolts. Widening an existing structure may require anchoring reinforcement to existing concrete members. The installation of such anchors or dowels will require competent persons and special grouting materials. The anchors may be installed to strengthen existing members. Anchors are not limited to reinforcement bars, anchoring of bolts to existing concrete is very common. Bolts can be anchored to fix signboards or expansion joints for bridge or building.  Figure 1 There are different grouting materials used to anchor bolts, rods, or reinforcement. The manual book of these materials will contain the necessary information, such as the diameter and depth of drilling for different sizes. These tables are taken from the Fischer manual. Fischer is an excellent grouting material. The tables showing the dimension of holes, the spacing between holes, and the edge of the concrete, also the min

The dry pack consists of portland cement, sand passing sieve no:16 (1.19 mm), and water sufficiently enough to hydrate the cement. The dry pack can be used to repair holes with a depth equal or more than the least surface dimension of the repair area. Also, it can be used to fill the holes of cone bolt, core holes, and hols for the injection of the grout. Also, it can be used to fill the area removed for crack repairing. However, the dry pack should not be used to fill the relatively low depressed area in which the lateral restraint cant be achieved. Also, it should not be used to fill the area behind the reinforcement.  Figure 1 For dry packing, the holes should be sharp and square at the surface of the member. The interior shape of the holes should be rounded, especially when the water-tightness is required. The interior of the holes should be cleaned and roughened with steel-wire rope to ensure good bonding of the dry pack. The dry pack can be prepared by mixing one part

Rebound hammer is a non-destructive test used to examine the hardened concrete. The principle of the rebound test is based on the rebound of a plunger. The plunger of the rebound hammer is pressed against a concrete surface. The hammer mass will be pushed back and secured to a pin. The impact spring is attached to the hammer mass, so it will be extended with the hammer mass. Then the hammer mass is released.finally, the mass will rebound against the concrete surface, as shown in figure no:1. The surface hardness and compressive strength will be correlated with the rebound of the spring controlled mass.  Figure 1 Figure 2 A rebound hammer can be used to evaluate the compressive strength of a concrete member, quality of concrete, and uniformity of concrete. The approximate impact energy required for the rebound of the hammer for different applications is shown in table no:1. Table 1 The procedure of conducting the rebound test will begin by the calibration

Safety should be the top priority at every project or establishment. Safe work should be implemented in every industry, such as construction, manufacturer, food, medical sectors, and others. The safety team is the front line defense in every construction project. The safety team always working on three approaches. The education of the construction team is the first approach. The safety engineer usually delivering a daily toolbox and weekly or monthly safety meeting. Toolbox talks aim to increase the awareness of workers regarding safe work procedures. Moreover, safety meetings will be held to discuss different safety issues, any site observation, how to close these unsafe observations, and how to improve the safe work system.  Figure 1 The second approach is the implementation of a safe work system to prevent the occurrence of injury or fatalities. Safety engineers should implement the hierarchy of controls. The control measures sequence should be, as shown in figure no:1. We s

A soundness test is used to determine the ability of an aggregate to resist the weathering actions. This test used to determine the resistance of aggregate to disintegration due to cyclic soaking and drying in a magnesium sulfate solution. The soundness test can be conducted for fine or coarse aggregates. The sample of aggregate should represent the material to be tested. The fine aggregate should be passing sieve 4.75 mm. The preparation of fine aggregate sample will involve the sieving and washing of aggregate sample on 300 μmm then drying it. Then the sample will be sieved on the sieves shown in table no:1 for a period of 8 to 12 minutes. From the fractions obtained by the sieving, select samples of sufficient size of 100 grams from each. The obtained samples from each fraction will be sieved again to refusal then placed in separate containers. If the sample has less than 30% retained on the 300 µm sieve, it is deemed to be too fine, and no test is done on any fraction. If any f