Total Surface Index of Aggregates In my previous post I discussed about surface index of aggregate for individual aggregate grading. But in actual practice we use combination of different aggregates having different sizes. So now the question that comes to our mind is whether we can represent surface index of mixed aggregates or not. The … Read more
Surface Index of Aggregates Surface index of aggregates is another way to represent the specific surface of aggregate. This method was suggested by Murdock. Murdock provided some empirical numbers to represent the specific surface of different aggregates grading (as shown in the table below). Surface Index Values for Different Aggregate Grading Sieve Size Within Which … Read more
Types Of Cement and Respective Indian Standards SlNo Types Of Cement Reference Indian Standard 1 Ordinary Portland Cement 33 Grade IS:269 2 Ordinary Portland Cement 43 Grade IS:8112 3 Ordinary Portland Cement 53 Grade IS:12269 4 Rapid Hardening Cement IS:8041 5 Extra Rapid Hardening Cement — 6 Sulphate Resisting Cement IS:12330 7 Portland Slag Cement … Read more
Specific Surface of Aggregate The surface area per unit weight of the material is termed as specific surface. This is an indirect measure of the aggregate grading. Specific surface increases with the reduction in the size of aggregate particle. The specific surface area of the fine aggregate is very much more than that of coarse … Read more
Which One Is Better For Concrete-Rounded or Angular Aggregate Angular aggregate are superior to rounded aggregate from the following two points of view. Angular aggregate exhibit a better interlocking effect in concrete, which property makes it superior in concrete used for roads and pavements. The total surface area of rough textured angular aggregate is more … Read more
Objective To measure flow value of concrete using flow table apparatus Equipment Flow table Slump cone shaped mould Wooden tamping bar Procedure Place the flow table on a leveled surface Clean the top of the table and inner surface of the mould using a damp cloth. Place the slump cone centrally on the table. … Read more
Angularity Number Angularity number is used to give an indication of shape of aggregate. The concept of angularity number was suggested by Shergold. It gives a qualitative representation of shape of aggregate. Angularity Number Test Angularity number test gives an idea of how angular the aggregate is. This is based on the percentage of voids … Read more
Important Notes on Setting Time Test of Cement o It is essential that cement set neither too rapidly nor too slowly. In the first case there might be insufficient time to transport and place the concrete before it becomes too rigid. In the second case too long a setting period tends to slow up the … Read more
Test Standard Reference IS:4031(Part 4):1988-Methods of physical tests for hydraulic cement (Determination of consistency of standard cement paste) Overview Standard consistency of a cement paste is defined as that consistency which will permit a vicat plunger having 10 mm dia and 50 mm length to penetrate to a depth of 33-35 mm from top of … Read more
Prevention to Damage Freshly laid concrete is liable to damage due to heavy impacts. In order to prevent damage: Floors should be covered in order to avoid surface damage Projecting ornamental members should be protected against falling material. Projecting reinforcing bars should not be used for climbing or subjected to severe usage. Stripping of forms … Read more