Question

CIVIL ENGINEERING AGGREGATE TEST LAB REPORT (ESSAY)

2.4Specific Gravity for Coarse Aggregates
2.4.1 Objective
2.4.2 Scope
2.4.3 Apparatus
2.4.4 Test Procedure
2.4.5 Test Result

These are the topics. Please use computer font.

Answer 1

It is the ratio of weight of a given volume of substance to the weight of equal volume of water under same temperature. (270c). Specific gravity of coarse aggregates varies from 2.7 to 2.9.

there are two methods to find specific gravity in laboratory

Basket and aggregate is removed from water and allow draining.

Immerse empty basket in water, lift and lower for 25 times and weighed in water (A2).

Find surface dried weight of aggregate (B).

Keep aggregate in oven at 100 to 1100c for 24 hrs.

It is then cooled and find weight (C).

Result

Specific gravity                                                      =                    

Apparent Specific gravity                                       =                  

Water absorption                                                    =                

where A = A1 – A2 , weight of saturated aggregate in water

            B = B1 – B2, weight of saturated surface dried aggregate

            C = weight of oven dried aggregate

OR

Apparatus

Procedure

     

o Note the empty weight of container, w1

o Fill the container with aggregate sample in 3 layers with one-third each time and tamp each layer with 25 strokes using tamping rod

o Strike off Surplus aggregate with tamping rod

o Note the Weight of container with aggregate ,w2

o Fill the container with aggregate with water to brim and note weight, w3

o Clean the container and fill with clean water and note the weight, w4

Result

Specific gravity                              =

                                                                          

                                                          =