Skip to main content

Tests on Stones

Tests on Stones


To certain the required properties of stones, the following tests can be conducted:

(i) crushing strength test
(ii) water absorption test
(iii) abrasion test
(iv) impact test
(v) acid test.

'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''

(i) Crushing Strength Test:

For conducting this test, specimen of size 40 × 40 × 40 mm are prepared from parent stone. Then the sides are finely dressed and placed in water for 3 days. The saturated specimen is provided with a layer of plaster of Paris on its top and bottom surfaces to get even surface so that load applied is distributed uniformly. Uniform load distribution can be obtained satisfactorily by providing a pair of 5 mm thick plywood instead of using plaster of Paris layer also.

The specimen so placed in the compression testing machine is loaded at the rate of 14 N/mm2 per minute. The crushing load is noted. Then crushing strength is equal to the crushing load divided by the area over which the load is applied. At least three specimen should be tested and the average should be taken as crushing strength.

(ii) Water Absorption Test:

For this test cube specimen weighing about 50 grams are prepared and the test is carried out in the steps given below:
(a) Note the weight of dry specimen as W1.
(b) Place the specimen in water for 24 hours.
(c) Take out the specimen, wipe out the surface with a piece of cloth and weigh the specimen.Let its weight be W2.
(d) Suspend the specimen freely in water and weight it. Let its weight be W3.
(e) Place the specimen in boiling water for 5 hours. Then take it out, wipe the surface with cloth and weigh it. Let this weight be W4 . Then,

Percentage absorption by weight =(W2- W1)/(W1)x100 -------(1)

Percentage absorption by volume =W2-W1/W2-W3X100--------(2)

Percentage porosity by volume =W4-W1/W2-W3X100--------(3)

Density =W1/W2 W1----------------------(4)
Specific gravity=W1/W2-W3-------------------------------------------(5)
∴ Saturation coefficient =Water absorption / Total porosity =W2-W1/W4-W1

(iii) Abrasion Test:

This test is carried out on stones which are used as aggregates for road construction. The test result indicate the suitability of stones against the grinding action under traffic. Any one of the following test may be conducted to find out the suitability of aggregates:
(i) Los Angeles abrasion test
(ii) Deval abrasion test
(iii) Dorry’s abrasion test.
However Los Angeles abrasion test is preferred since these test results are having good correlation with the performance of the pavements.
The Los Angeles apparatus  consists of a hollow cylinder 0.7 m inside diameter and
0.5 m long with both ends closed.
It is mounted on a frame so that it can be rotated about horizontal axis. IS code has standardized the test procedure for different gradation of specimen. Along with specified weight of specimen a specified number of cast iron balls of 48 mm diameter are placed in the cylinder.Then the cylinder is rotated at a speed of 30 to 33 rpm for specified number of times (500 to 1000). Then the aggregate is removed and sieved on 1.7 mm. IS sieve. The weight of aggregate passing is found.
Then Los Angeles value is found as = Weight of aggregate passing through sieve/
Original weight × 100.
The following values are recommended for road works:
For bituminous mixes – 30%
For base course – 50%

(iv) Impact Test:

The resistance of stones to impact is found by conducting tests in impacting
testing machine  It consists of a frame with guides in which a metal hammer weighing 13.5 to 15 kg can freely fall from a height of 380 mm.

Aggregates of size 10 mm to 12.5 mm are filled in cylinder in 3 equal layers; each layer being tamped 25 times. The same is then transferred to the cup and again tamped 25 times. The hammer is then allowed to fall freely on the specimen 15 times. The specimen is then sieved through 2.36 mm

Comments

Popular post

What is Slump Test of Concrete-Cone Test Procedure | Workability of Concrete

Slump Test of Concrete-Cone Test Procedure | Workability of Concrete Slump test procedure is to determine the workability of concrete. One of the major problems that you had faced in your field work is concrete compaction during mixing.After mix design, you may have doubt, is this design will be ok? Yes, your design willl be ok in terms of strenght point of view of concrete.But the main problem arises when the mixing of fresh concrete, the compaction of fresh concrete will be very tough.In this situation, you can add some plasticizers without affecting your water-cement ratio or cement-aggregate ratio. Before adding plasticizers or superplasticizers to your fresh concrete, you need to check the workability of your concrete.The slump test is used for checking the workability of concrete.Let us check how can we do slump test of fresh concrete. Apparatus used for cone test procedure 1)Measuring scale 2)Tamping rod 3)Base plate 4)Nonporous base plate 5)Mould for slump test. ...

WHAT ARE THE DESIGN PROCEDURES FOR A BUILDING FOUNDATION?

  DESIGN PROCEDURES FOR A BUILDING FOUNDATION 1. DECIDE THE LOCATION OF COLUMNS & FOUNDATION AND TYPE OF LOADS ACTING ON THEM.(E.X DEAL LOAD,  LIVE LOAD OR WIND LOAD) 2. ESTIMATE ALLOWABLE BEARING PRESSURE OF SOIL USING GROUND INVESTIGATION REPORT. 3. DECIDE DEPTH OF FOUNDATION 4. CALCULATE FOUNDATION AREA 5. DETERMINE VARIATION IN VERTICAL STRESSES 6. CALCULATE SETTLEMENT 7. COST CONTROL 8. CONSIDER TIME 9. VARIATION IN GROUND CONDITION 1. DECIDE THE LOCATION OF COLUMNS & FOUNDATION AND TYPE OF LOADS ACTING ON THEM.(E.X DEAL LOAD,  LIVE LOAD OR WIND LOAD) On the building plan, the position of columns and load bearing walls should be marked, and any other induced loading and bending moments. The loads should be classified into dead, imposed and wind loading, giving the appropriate partial safety factors for these loads. 2. ESTIMATE ALLOWABLE BEARING PRESSURE OF SOIL USING GROUND INVESTIGATION REPORT. From a study of the site ground investigation (if available), th...

What’s the difference between m20 and c20 grade concrete?

 A concrete of Grade C20 means that the concrete will have a compression resistance of 20 N/mm² per square millimeter in 28 days. Proportion for grade C20. C20 is 1:2:4 (1 part cement, 2 parts fine aggregate, and 4 parts coarse aggregate.) where as C20 symbolizes a Cylindrical sample in which cement, fine aggregates, coarse aggregates are mixed in such a ratio that its characteristic compressive strength is 20 N/mm² after 28 days of curing. Fig:- Concrete specimen for testing Generally Strength of Cylinder sample= 0.8 x Strength of Cube. example:- M20 is equivalent to C25 M20 means the grade of concrete is defined as the minimum strength of concrete after 28 days. For the M20 Grade of concrete, The letter ‘M’ refers to the mix, and 20 represents the characteristic strength of concrete in MPa or N/mm². The specified characteristic strength of concrete is determined for 150mm size cube at 28 days. The Characteristic Compressive strength of concrete is defined as the strength of conc...

Different methods of road construction in civil engineering

Different methods of road construction in civil engineering 1) Concrete: It is a common option for road construction purposes as they are a solid material and can be used for building walls and local roads. This method is considerably less prone to wear and tear defects like rutting, cracking, stripping loss of texture, and potholes. This is the main reason for its wide usage. 2) Asphalt: This method of construction replacing concrete method in these days. They are very durable, water-resistant and can go more longer then the concrete. The major advantage of asphalt over concrete is its price. Concrete is very expensive as compared to asphalt. Moreover, asphalt includes low noise during pavement and it is easy to handle it for repairing and maintenance. That is why it is widely accepted and used by the people for the purpose of pavement surfacing. 3) Composite: This method is widely used for the maintenance, recycling, and rehabilitation of the roads. The composite m...

Design Requirement of reinforced Concentrate slab

Table  Content 1 Effective span for concentrate slab design 2 Limiting stiffness 3 Minimum reinforcement 4 Maximum diameter of bar 5 Distribution reinforcement concentrate for slab design 6 Cover to reinforcement Let discuss briefly '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 1. Effective Span for concrete slab design For simply supported slab Minimum of clear span plus effective depth of slab Center to center...

#4 Basic Factors Why Concentrate Cracks?

  WHAT IS CONCRETE : Concrete is a building material which made from mixture of cement , sand ,crush or gravel and water. and we poured this mixture in the form work which can give us the different shapes of element like stone which is too mush strong. WHY CONCRETE CRACKS : 1: Excess of water in concrete 2: Improper Compaction of concrete 3: Rapid drying of concrete 4: Temperature Variation 1: EXCESS OF WATER IN CONCRETE Concrete does not required much water to get maximum strength . we required limit water in concrete to achieve the maximum strength of concrete . when we increase the water in concrete so it can lose the strength , so therefore concrete can crack. water is just reducing in concrete to make workabality of concrete . so increasing of water can reduce the strength of concrete. 2: IMPROPER COMPACTION OF CONCRETE before placing concrete we have to proper compact the soil. and after that when we placed concrete so concrete should be compacted properly . when the con...

What Is Splicing of Reinforcement Bars?,Rebar Formula and Brief Example

 What Is Splicing of Reinforcement Bars? 🏷Splicing of reinforcement bars, commonly known as rebars, refers to the process of connecting two or more rebars in a reinforced concrete structure to ensure a continuous and load-resistant structure. 🚧It is a critical practice in construction to transfer the stresses from one bar to another effectively, maintaining structural integrity. 💫Methods of Splicing Reinforcement Bars There are three primary methods of splicing reinforcement bars: ❇️1. Lap Splice A lap splice is the most widely used method in reinforced concrete structures. In this technique, two rebars are overlapped and tied together using binding wires. The overlap length, also known as the lap length, is crucial for ensuring the splice’s strength. ⏺It is determined based on factors such as: • The diameter of the rebars. • The grade of concrete. • The specific application of the structure. ▶️The lap splice is easy to implement and cost-effective but may require additional con...