Needle Vibrator These concrete vibrators are also referred to as poker or immersion vibrator. These are extensively used in building industry. A needle vibrator consists of a cylindrical casing made of steel and is vibrated by means of a flexible drive with an outer tube run from an operating machine which can be run by … Read more
Comparison between Ordinary & Performance Graded Binders The primary differences between ordinary graded binder and performance graded binder is given in the following table Ordinary Graded Binders Performance Graded Binders Binders are graded either based upon penetration or viscosity Binders are graded based upon pavement temperature, which are close to in service conditions of pavements … Read more
Factors Affecting Transportation The success of transportation engineering depends upon the co-ordination between the three primary elements, namely the vehicles, the roadways, and the road users. Their characteristics affect the performance of the transportation system and the transportation engineer should have fairly good understanding about them. This post elaborated salient human, vehicle, and road factors … Read more
Different Forms of Bitumen 1. Cutback Bitumen Normal practice is to heat bitumen to reduce its viscosity. In some situations preference is given to use liquid binders such as cutback bitumen. In cutback bitumen suitable solvent is used to lower the viscosity of the bitumen. From the environmental point of view also cutback bitumen is … Read more
Processing of Borrow Area Soils / Backfill Materials The construction of subsurface structures often requires the construction of elements of the structure within or upon large masses of backfill. The proper functioning of these elements are often critically affected by adverse behavioral characteristics of the backfill. Behavioral characteristics are related to material type, water content … Read more
Types of Backfill Materials Different types of backfill materials are used in construction industry. Backfill materials that are commonly used are described below with their engineering properties. 1. Coarse-grained soils Coarse-grained soils include gravelly and sandy soils and range from clayey sands (SC) through the well-graded gravels of gravel-sand mixtures (GW) with little or no … Read more
Types of Concrete Pavement In pavement construction, three different concrete pavement design types are commonly used: Jointed Plain Concrete Pavements (JPCP), Jointed Reinforced Concrete Pavements (JRCP), and Continuously Reinforced Concrete Pavements (CRCP) Each of these design types can provide long-lasting pavements that meet or exceed specific project requirements. Each type is suitable for new construction, … Read more
Aggregates for Asphalt Concrete The amount of aggregates for asphalt concrete mixtures is generally 90 to 95 percent by weight and 75 to 85 percent by volume. Aggregates are primarily responsible for the load supporting capacity of a pavement. Aggregate has been defined as any inert mineral material used for mixing in graduated particles or … Read more
Joints in Rigid Pavement Provisions of joints are necessitated due to: 1) Expansion, contraction and warping of concrete slabs resulting from temperature and moisture changes; 2) Facilitate a break in the construction at the end of day’s work or for any unexpected interruption to work progress; and 3) Construction of pavements in lanes of convenient … Read more
Failure of Flexible Pavement A typical flexible pavement consist of following 4 layers Soil subgrade Sub-base course Base course Surface or wearing course If due to any reason, any of the above mentioned layers loses its stability, it will lead to failure of the whole pavement. There are many types of failures of flexible pavement, … Read more
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