WHAT IS THE IMPORTANCE OF AGGREGATE GRADATION IN CONCRETE?

Concrete is prepared by mixing aggregate, cement and water in such a proportion that it becomes workable in its plastic state and durable in its hardened state. Our aim is to satisfy both of these requirements i.e. workability and durability. Importance in terms of Workability A workable concrete can be achieved by adding more water, … Read more

WHAT ARE THE QUALITY REQUIREMENTS OF AGGREGATES?

Aggregate should have the following qualities Quality Requirements of Aggregate Aggregates should be strong, hard, dense, durable, clear and free from veins and adherent coating. Aggregates should be free from injurious amounts of disintegrated pieces, alkalis, vegetable matter and other deleterious substances. Flaky and Elongated pieces should not be present in aggregate mass. Aggregate crushing … Read more

WHY DETERMINATION OF SETTING TIME OF CONCRETE IS IMPORTANT?

Determination of setting time of concrete helps a site engineer in guiding the following areas. Importance of Setting Time of Concrete Whether or not to use any plasticizer To find out effectiveness of set controlling admixture Regulating maximum time of mixing transit, placing and compacting Whether or not to provide protection against adverse weather condition … Read more

WHAT ARE THE FACTORS RESPONSIBLE FOR SETTING TIME OF CONCRETE?

The setting time of concrete depends upon following factors, such as Water-cement ratio Temperature condition Type of cement used Use of mineral admixture Use of chemical admixture (such as plasticizer) Other factors which may affect the setting time of concrete includes Absorption of mixing water by aggregates Grinding of aggregates in the mixer Of all … Read more

WHAT IS SETTING TIME OF CONCRETE?

Penetration Resistance Apparatus

The various process involved in any concreting operation involves the following stages. Mixing Transporting Placing Consolidating As concrete passes from one stage to another, it starts to lose its plasticity characteristics. If after placing it is not disturbed for a longer time period, then it starts to become stiffening. As a result concrete changes its … Read more

DETERMINATION OF LIGHT WEIGHT PIECES (COAL & LIGNITE) IN AGGREGATE (IS-2386-PART-2)

Objective To determine the approximate percentage of light weight pieces (i.e. coal & lignite) in aggregate by means of sink-float separation in a heavy liquid of suitable specific gravity. Apparatus Name Capacity Least Count Balance 500 g 0.1 g Balance 5000 g 1 g Oven 100 to 1100C   Sieve 300 micron, 4.75 mm   … Read more

FINENESS OF CEMENT BY BLAINES AIR PERMEABILITY METHOD (IS-4031-PART-2)

Overview Blaine’s air permeability apparatus consists essentially of a means of drawing a definite quantity of air through a prepared bed of cement of definite porosity. The fineness is expressed as a total surface area in square centimeters per gram. Apparatus Measuring instruments Name Range Accuracy Blaine air permeability apparatus Refer to IS:5516 Balance 3 … Read more

WHAT IS QUICKSAND AND PIPING?

Quicksand Quicksand is a condition and not a soil type. This condition is created in saturated thick layers of loose fine sandy soils when disturbed either due to vibration, such as, from pile driving in the neighborhood, or due to pressure of flowing water (at the time of heavy pumping in excavation). The particles, in … Read more