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 Single Graded Aggregate TABLE-1 Sieve Size Within … Read more
Plastic shrinkage cracking (as shown below) is caused by rapid drying of the concrete surface. They can occur at any time of the year, from cooler low-humidity weather conditions to, in particular, hot weather conditions involving any one or a combination of high temperature, low humidity and wind. These types of cracks occur while the … Read more
Sandblasting Sand blasting is the process of roughening and cleaning the surface of old and set concrete (or in any corroded steel surface) by means of coarse sand and air applied under pressure of 90 to 100 pounds per square inch (6.33 to 7.03 kilogram per square centimeter) through a nozzle, so as to erode … Read more
Quality Control of Concrete Construction Quality of concrete construction on site can be accomplished in three distinct stages as follow Quality control before concreting Quality control during concreting Quality control after construction Stage-1 (Quality Control Before Concreting) This stage of quality control consists of two steps. Checking of specification requirements regarding excavation, forms, reinforcement and … Read more
Honeycomb Repair in Concrete Surface Honeycomb and larger surface voids require procedures resembling those for typical concrete repairs. But there’s nothing typical about the recommended approaches to repairing these voids. They vary greatly. While repairing voids or honeycomb in concrete surface, the most common question that arises is what should be the thickness of the … Read more
Objective To determine the Flexural Strength of Concrete, which comes into play when a road slab with inadequate sub-grade support is subjected to wheel loads and / or there are volume changes due to temperature / shrinking. Reference Standards IS: 516 (Part 1/Sec 1) : 2021 – Hardened Concrete – Methods of Test Part 1: Testing … Read more
Concrete structures which are subjected to freezing and thawing are likely to deteriorate earlier. Structures which are mostly affected under similar climatic conditions due to freezing and thawing are the exposed surfaces of the top 60 cm of walls, piers, parapets, cornices etc. the durability of such structures can be improved by adopting certain weather … Read more
Theory The bond strength is the measure of the effectiveness of the grip between concrete and steel and has no standard quantitative definition. In pull out tests on plain bars, the maximum load generally represents the bond strength that can be developed between concrete and steel. With plain bars the maximum load is not very … Read more
Effect of Shrinkage on Concrete Structure When concrete structures are not permanently water-saturated, it starts to lose moisture and starts to shrink from the time when the process of curing ceases. The structural effects of shrinkage area as follow. 1. Joints Shrinkage of concrete between movement joints causes joints to open or makes it wider. … Read more
Slump Cone Test of Fresh Concrete Object This test is performed to measure consistency or workability of fresh concrete, where the nominal maximum size of aggregate does not exceed 38 mm using slump test apparatus. Reference Standards IS : 1199 – 1959 – Method of sampling and analysis of concrete. Equipment & Apparatus Slump cone (Height … Read more
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