California Bearing Ratio or CBR test is the ratio of the force per unit area required to penetrate a soil mass with a standard circular piston of 50 mm dia, at the rate of 1.25 mm/min to that of force required to penetrate sample of compacted stone having CBR of 100%. The standard load corresponding … Read more
Objective This test is intended to study the resistance of coarse and fine aggregates to weathering action and to judge the durability of the coarse aggregate. Apparatus Name Capacity Least count Balance 500 g 0.1 g Balance 5000 g 1 g Oven 105 to 1100C Sieves 80 mm, 63 mm, 40 mm, 31.5 mm, … Read more
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
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
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
The properties of a soil mixture are influenced more by variation in moisture content than by any other cause. Saturated soils are improved in strength by drainage and dry soils lose strength by saturation. A water logged ground is undesirable because of its low bearing capacity. Effect on Fine Grained Soil Fine grained (clayey) soils … Read more
Objective To determine moisture content and dry density relationship using heavy compaction or modified compaction method as per IS-2720-Part-8. Apparatus • Metal mould (volume = 1000 cm3) • Balance (capacity = 10 kg, least count = 1g) • Oven (105 to 1100C) • Sieve (19 mm) • Metal rammer (weight = 4.9 kg) Procedure Dry … Read more
Objective Determination of initial and final setting time of concrete as per IS-8142-1976. Apparatus • Non absorptive metal container having minimum lateral dimension of 150 mm and minimum depth of 150 mm. • Penetration resistance apparatus having a pressure gauge of capacity 700 to 900 N. Removable needles of 645, 323, 161, 65, 32 & … Read more
To get better efficiency, the sequence of charging the loading skip is as under 1. First place half the quantity of coarse aggregate in the skip. 2. Place half the quantity of fine aggregate over the previously placed coarse aggregate. 3. Then pour full quantity of cement (i.e. one bag of cement) over it. 4. … Read more
For preparation of special products like precast concrete membranes, some special compaction methods are used, such as • Vibropressing • Shock • Centrifugation • Air jets Vibropressing Compacting in this method is effected by applying external pressure on top and vibrating from bottom. Table vibrators are usually made use of in this process. This process … Read more