concretebasics.org: your guide to cement & concrete

Concrete Learning Center

	Cement
1	Which is the more popular process for manufacturing of cement: Wet/Dry? , Why?
2	How does incomplete hydration affect the strength of concrete?
3	How long does hydration continue?
	Aggregate
1	What is the difference between “Maximum Size” and “Nominal Maximum Size” of aggregates?
2	Why the surface area of aggregate increases as the particle size decreases?
3	What is the significance of aggregate grading?
4	What is significance of specifying the maximum size of aggregates?
5	What is the significance of specifying the amount of material passing the 300µm and 150 µm (ASTM No. 50 and 100) sieves?
6	Why richer mix requires a lower content of fine sand?
7	Why is presence (in excess) of Flaky or Elongated particles in concrete considered undesirable?
8	Why aggregates of low/moderate strength & modulus of elasticity can be valuable in preserving the durability of concrete?
	Water
1	In many specifications, quality of water is covered by a clause saying that mixing water should be fit for drinking. What is its significance? Will drinking water always be suitable as mixing water?


	Admixture
1	What is the difference between conventional water-reducing admixtures & the super plasticizers?


	Concrete
1	What is the difference between “High Strength Concrete” & “High Performance Concrete”?
2	What is “No Fines” Concrete?
3	Bleeding results is reduction of Water-Cement ratio. Then why is it considered harmful?
4	How is the mix for Roller Compacted Concrete different from the mix of Conventional Concrete?
5	How is Self Compacting Concrete (SCC) different from High Slump Concrete?
6	What is the significance of Mixing time of concrete?
7	Why do concrete specifications recommend a rate of withdrawal for immersion vibrators?
8	Why “slicing” along the form is required to be done?
9	Why vibration improves strength of Concrete?
10	How does Revibration help? What happens during Revibration?
11	What are the reasons for formation of cracks, blisters & powdery layer on Concrete Surface?
12	How can Fire Performance of High Strength Concrete be improved?
13	What is the difference between Prestressing Tendons & Prestressing Strands?
14	What is the difference between Prestressing Duct & Prestressing Sheathing?
15	What is the difference between Entrapped air & Entrained air?
16	Does the Portland stone really resemble the concrete made with Portland Cement?
17	Why cylindrical specimens are required to be capped for compression testing whereas there is no such requirement for cubical specimens?
18	Does strength of capping material (in case of cylindrical specimens) affect the measured strength of concrete?
19	Why grinding is not done in lieu of capping for preparation of cylinderical specimens for compression test grinding method?
	Shotcrete
1	What is the significance of Coarse Aggregate to Fine aggregate ratio in Shotcrete mix design?
2	How do we simultaneously satisfy the conflicting requirements of “Pumpablity” & “Shootability” of shotcrete?
3	Does usage of accelerators in shotcrete affect its strength adversely?

This section is a Question-Answer forum wherein the Concretetechgroup provides the answers to questions raised by users of this website. Most of the times the answers are based on articles contributed by users. This section was started on Feb 04 , 2008 on feedback from our valued users. Users are requested to mail their questions related to concrete consituents, mix, concreting process & concrete technology to support@concretebasics.org. The answers will be provided by Concretetechgroup within three working days.