QAQC in Construction

There are different types of building blocks used in Pakistan. Before discussing their prices and types. Let’s talk about their composition and history. HISTORY In contemporary construction, cement and concrete blocks are important and versatile building materials. They are mainly built for construction purposes. They are used in multiple  applications such as, for the construction of fountains, walls, floors, and walkways. Cement and concrete blocks have been in use for a very long time. The Romans used to build their colosseum and iconic structures with blocks. In the present time, blocks are used for modern constructions. Now, they are used for the fabrication of housing societies, commercial and industrial buildings. COMPOSITION Concrete blocks are composed of a mixture of cement and aggregates. Cement holds the other materials together. Sand and gravel gives strength and durability to the block. On the other hand, cement blocks are similar to concrete blocks, although they are...

1. Drying Shrinkage Concrete by nature is a porous material. This means that when it is curing, the water in the concrete takes up space. As concrete hardens, it loses its moisture through evaporation resulting in empty capillary pores and a slightly smaller shape. This process is known as drying shrinkage. Since concrete is very rigid, this shrinkage causes an increase in tensile stress, which may lead to, cracking, internal warping, or external deflection. Concrete cracks when the drying shrinkage stresses exceed the tensile strength of the concrete. The spacing and size of cracks depend on the amount of shrinkage, degree of restraint, and amount and type of reinforcement. Drying shrinkage is the number one reason for cracks in concrete. 2. Lack of / improper use of control joints Control joints are most commonly installed in slab-on-grade concrete that is used in places such as driveways, pavements, house slabs, basement floors, and industrial spaces.  Control joints are general...

Cementitious Materials in Concrete Define and classify various cementitious materials; Understand the effects of cement fineness on water demand and concrete strength properties Recognize the importance of controlling the heat of hydration in concrete; and Identify the types of blended cement and the performance benefits of each for certain applications. List the standard tests used to determine properties of hydraulic cement; Understand why the water demand changes when using fly ash and pozzolans; Discuss the differences in strength gain for concretes with and without pozzolan replacement of cement; and Recognize the advantages of using ground granulated blast furnace slag and silica fume in concrete. Explain the synergistic effects of using multiple Supplementary Cementitious Materials (SCMs) in a concrete mixture. Recall methodologies for evaluating ternary and quaternary blends of materials for use in concrete. Describe considerations for construction using ternary and quaternary ...

A person conducting a business or undertaking (PCBU) must manage the risks associated with confined space, such as a silo, at a workplace including confined space entry permits, signage, communication, emergency procedures and written risk assessments. Designers, importers, suppliers and manufacturers have a standard duty to eliminate or minimise entry into a confined space, so far as is reasonably practicable, in relation to the plant or structure. General safety The atmosphere in silos can be dangerous Silos should be located clear of houses, overhead power lines, animals, children and water holes The dust in a silo may be explosive particularly if the humidity is low –  do not smoke  or have any other ignition sources High temperatures in silos can result in heat stress for anyone entering them. If possible,  do the job from outside Wear appropriate respiratory equipment particularly when fumigating Safe entry Do not enter a silo unless you have to If...

What are the differences in these cement types and how are they tested, produced, and identified in practice? In the most general sense, portland cement is produced by heating sources of lime, iron, silica, and alumina to clinkering temperature (1,371 to 1,538 degrees Centigrade) in a rotating kiln, then grinding the clinker to a fine powder. The heating that occurs in the kiln transforms the raw materials into new chemical compounds. Therefore, the chemical composition of the cement is defined by the mass percentages and composition of the raw sources of lime, iron, silica, and alumina as well as the temperature and duration of heating. It is this variation in raw materials source and the plant-specific characteristics, as well as the finishing processes (i.e. grinding and possible blending with gypsum, limestone, or supplementary cementing materials), that define the cement produced. Standards? To ensure a level of consistency between cement-producing plants, certain chemi...