Rules of Thumb on Concrete Mix Adding 4 liters of water to 1 cubic meter of freshly mixed concrete will: Increase slump about 25 mm Decrease compressive strength about 1.5 to 2.0 N/mm2 Increase shrinkage potential about 10% Waste as much as ¼ bag of cement If Freshly Mixed Concrete Temperature Increases 1 degree Celsius: … Read more
Specification For Mechanical Properties of High Strength Deformed Bars & Wires Reference IS-1786-2008-High strength deformed steel bars & wires for concrete reinforcement Type 0.2% proof stress/ yield stress, Min, N/mm2 0.2% proof stress/ yield stress, Max, N/mm2 TS/YS ratio Elongation, %, Min, on gauge length 5.65√A, where A is the cross-sectional area of the test … Read more
Our aim is to mix the fine aggregate & coarse aggregate in such a ratio so that the final combined aggregate gives the specified or desirable surface index. Follow the below mentioned steps to find the proportion of fine to coarse aggregate. Procedure Calculate the total surface index of fine aggregate (let it be x) … Read more
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