Science topic

Concrete Material Technology - Science topic

Explore the latest questions and answers in Concrete Material Technology, and find Concrete Material Technology experts.
Questions related to Concrete Material Technology
  • asked a question related to Concrete Material Technology
Question
1 answer
I am really curious to know why we make clinker in oxidizing conditions? of course because of burning the fuel for the kiln but do the environment really affects the clinker quality.
What will happen to the cement quality if the Clinkerization reaction happen in reducing environment?
regards
Saurabh
Relevant answer
Answer
If the clinkerization reaction (the process of forming clinker, the main component of cement, from raw materials such as limestone and clay) occurs in a reducing environment, the quality of the cement may be affected. In a reducing environment, the iron in the raw materials may be reduced to metallic iron, which can cause the cement to be less durable and less resistant to sulfates. Additionally, the formation of metallic iron can lead to a decrease in the overall strength of the cement. Therefore, it is important to maintain an appropriate level of oxygen during the clinkerization reaction to ensure optimal cement quality.
  • asked a question related to Concrete Material Technology
Question
5 answers
How can I specify Acceptance strains of concrete and steel materials for Immediate Occupancy (IO),Life Safety (LS) and Collapse Prevention (CP) levels in Nonlinear Analysis?
Relevant answer
Hello, just wondering if you've found out where to get this acceptance criteria
  • asked a question related to Concrete Material Technology
Question
3 answers
Relevant answer
Answer
This is a good question.
  • asked a question related to Concrete Material Technology
Question
21 answers
Some papers are giving that the ductility is directly proportional to the compressive strength of concrete. If so, what will be the relation between these two
Relevant answer
Answer
It is well known fact that increase in compressive strength decreases ductility of concrete. Due to which we add different types of fibers to improve its ductility.
  • asked a question related to Concrete Material Technology
Question
10 answers
I have stadium stairs made of concrete, and i need to pick an adhesive material that give a good bonding strength and can resist some environmental factors such as hot and cold weather without peeling off. ( ceramic- polymer composite).. I can،t wait to read your esteemed answers.
Relevant answer
Answer
I would like to recommend Silicone Rubber Compounds - RTV 2 components which perform the ability of high thermal conductivity and adhesive. Some famous brand names which you can refer ShinEtsu, Momentive, or Dow-Corning.
References:
Best regards.
  • asked a question related to Concrete Material Technology
Question
3 answers
What would be the practical range of compressive strengths of concrete of a foundation pile? 
Can it go as low as 25 MPa?
Really interested to know the lowest allowable for residential buildings
Faizal
Relevant answer
Answer
The min cement content mentioned is 400kg/m3 and says m20. Even with 175kg/m3 it will be min m30
  • asked a question related to Concrete Material Technology
Question
6 answers
I want to study on properties of grout admixed with pozzolans an bentonite  . but i could find any design grout mixing(without aggregate). how to choose W/S ratio??is there any code?
Relevant answer
Answer
What is your desired value for f'c and which code are you going to use for the concrete mixture?
  • asked a question related to Concrete Material Technology
Question
13 answers
As per my previous concepts, the ductility of concrete in uni-axial compression decreases as the compressive strength increases.(As from the stress strain diagram, a low strength concrete fails at higher strain levels)
But when we talk about the structural elements i.e, Flexure members, Compression members numerous sources on the internet say " That the ductility of the concrete increases with the increase in the compressive strength" What could be a good justification to this? Please answer in the light of following:
1) Is it because we have improved shear strength attributed with higher strength?
2) The curvature ductility increases with the increase in compressive (Fig Attached below)
So can someone argue, that a column in pure axial state , its ductility decreases, but when we have some eccentricity ( i.e, bending) the ductility increases
Thanks in Advance!
Relevant answer
Answer
Usually, the more compressive strength concrete has, the less its ductility becomes.
  • asked a question related to Concrete Material Technology
Question
5 answers
Please help me find a brief history of Recycled Concrete Aggregate (RCA) CLASSIFICATION in the U.S. any paper or Official U.S. state DOTs' document.
Target:
To find out how many classifications of RCA we have and what is the difference?
Thank you all.
Relevant answer
Answer
I can give you informations on the classification of recycled aggregates in Germany. We have 4 types. 2 of them are allowed in constructive, load bearing concrete in limited portions. More information you can found in
https://youtu.be/_D9r9w2S0hc or in my book "Baustoffrecycling" in German. I just preparing in English version.
I would be interested in U.S. classification to.
  • asked a question related to Concrete Material Technology
Question
5 answers
Cement mill with spray nozzles are being used since many years. Experience suggests that it sometime helps in preventing unnecessary increase of mill temperature which in turn gives no harm to cement quality. On the other side, sometime spray nozzle does not work properly due to coating formation on it and also causes unnecessary stoppages of cement mill due to high temperature. What should be the soluton to avoid coating fornmation on spray nozzle.
Relevant answer
Answer
Bhautesh Mistry I am very much interested in the question you have raised. I also have a cement mill nozzle which keeps blocking especially when there is a power failure. Have you found a solution to your problem? if yes, please do share. Also is there a special type of nozzle that helps prevent this blockage? How efficient is the use of grinding aid in the nozzle in preventing this blockage and improving overall grinding efficiency? Thank you.
  • asked a question related to Concrete Material Technology
Question
5 answers
I want to use MTS testing machine with maximum capacity of 300 KN, but I don't know, which size of specimens is suitable to test compression and bending strength of bio composite concrete to use MTS testing Machine (E45, 300KN) ? what is your recommendation, why, and according to which standard code? #concrete #MTS_E45
Relevant answer
Answer
Afshin Turk hi dear
how about cubic sample? man motoasefane be hamin ye dastgah dastresi daram chon kolan kare ma test concrete nist. baraye flexural strength test che size pishnahad midin?
  • asked a question related to Concrete Material Technology
Question
46 answers
Upon your experience on site and concrete on site, the phenomena of discolored of concrete might happens... how do you fix that?
Relevant answer
Answer
Abdelkader Mohamed Abdelkader Elsayed .... Thanks for answering ..
  • asked a question related to Concrete Material Technology
Question
11 answers
To study the cementitious properties of cement substitute material should all other parameters be kept constant or should be changed?
Relevant answer
Answer
Hi Richa,
Cement Replacing Materials (CRM) actually binding materials. Although there may not be a significant change using CRM by it's volume and wt. But cement is actually in concrete 10-15% only. For that keeping aggregate percentage constant will be appropriate and other factors need to be analyzed.
  • asked a question related to Concrete Material Technology
Question
7 answers
Dear researchers,
I am looking for the following research papers:
-Carino, N.J., 1984, “The Maturity Method: Theory and Application,” Journal of Cement, Concrete, and Aggregates (ASTM), Vol. 6, No. 2, Winter, pp. 61-73.
- Knudsen, T., 1984, “The Dispersion Model for Hydration of Portland Cement: I. General Concepts,” Cement and Concrete Research, Vol. 14, pp. 622-630.
- Freiesleben Hansen, P. and Pedersen, J., 1985, “Curing of Concrete Structures,” CEB Information Bulletin 166, May, 42 p.
- Bezjaka, A., 1986, " An extension of the dispersion model for the hydration of Portland cement," Cement and Concrete Research, Vol. 16, pp. 260-264.
They are quite old papers, so really hard to find them. If anyone has these papers, could you please share them with me? Would really appreciate your help.
Kind Regards,
Minh Ho
Relevant answer
Answer
Thanks
Nazanin Fallahi
  • asked a question related to Concrete Material Technology
Question
6 answers
What do you think how important, for segregation coefficient of SCC, could be very small superplasticizer overlaps during the process of making SCC? I made some observations in my work:
Relevant answer
  • asked a question related to Concrete Material Technology
Question
18 answers
Some good models have been proposed for compression (e.g. Mander et al (1989), Scott et al (1982)). But which model to choose for tension?
Relevant answer
  • asked a question related to Concrete Material Technology
Question
42 answers
Concrete strength measured using concrete cubes produce a results different than concrete cylinders.  Conservative estimates put concrete cylinders at 80% of concrete cubes, for high-strength concrete some say the percentage is near 100%.
Does anyone have experience using a cube strength in place of a cylinder's or vise-versa?  Would anyone use a "translated" cube strength specification for design?  Would anyone use a translated cube strength in place of a cylinder test for acceptance?
Relevant answer
  • asked a question related to Concrete Material Technology
Question
7 answers
What are the best temperature control techniques for construction of Roller Compacted Concrete Dam
Relevant answer
  • asked a question related to Concrete Material Technology
Question
2 answers
There are many confinement models for predicting the strength & stress-strain behavior of FRP confined concrete. Those are mostly two types; one is design-oriented model and another is analysis-oriented model. Is there anyone who can explain me the difference between these two types of models and how can we apply these models practically?
Relevant answer
  • asked a question related to Concrete Material Technology
Question
6 answers
To all structural or geotechnical engineers, or people in the construcion materiales area, what would be your opinion of a natural concrete (with no Portland Cement) but using cohesive fine soil as cement (The water proofing problem would be solve later), now from the resistence point of view, the feasibility. Appreciate your comments
Relevant answer
Answer
In any case, such a thought can be taken forward only with the incorporation of a primary binding material which has a sufficient amount of reactive CaO+SiO2+Al2O3. In addition the clay should be activated through suitable processing or by addition of an activating agent in the matrix, otherwise the compromise on strength and durability would be higher.
  • asked a question related to Concrete Material Technology
Question
6 answers
Was it to physically identify crack orientation/inclination and differentiate it between lateral, flexural, shear cracks etc? Or is it for some other function i dont know about.
Relevant answer
Answer
Grid provides you the pattern of cracking and directions to allow you to study the detailing of reinforcement required in the joint.
  • asked a question related to Concrete Material Technology
Question
15 answers
I'm looking for the ratios of cement : sand : aggregates + water.
Please reply by referring valid references.
Relevant answer
Answer
Dear, the mix design depends mainly on the properties of materials which is variable. Based on my experiance, the following mix can show 40 MPa strength. 1:1.5:2.75, w/c ratio 0,4.
  • asked a question related to Concrete Material Technology
  • asked a question related to Concrete Material Technology
Question
3 answers
One of the apparatus required for freeze and thaw test according to ASTM C666 is the dynamic testing apparatus. This apparatus is used to obtain the relative dynamic modulus of elasticity and durability factor of the concrete.
However, in case where the apparatus is not available, what other apparatus or parameter can be used ?
Few studies have used UPV as an alternative, but i'm still seeking for alternative methods.
Thanks
Relevant answer
  • asked a question related to Concrete Material Technology
Question
4 answers
Non destructive tests equipment for concrete are quite expensive and not readily available. Is there any non destructive test that can be improvised or built with commonly available materials to determine the strength or/and permeability properties of concrete and other cementitious composites?
Relevant answer
Answer
There is some developing research that utilises surface water flow to predict concrete permeability and durability characteristics. This research determines the relative covercrete skin permeability which can be standardised for various concrete parameters such as strength, porosity, and durability. You can get an idea of how it works from this link (at least through the images). http://wdnsword.iis.u-tokyo.ac.jp/research/IISopen/Kikuchi_2012.pdf
  • asked a question related to Concrete Material Technology
Question
9 answers
I have the experimental results of brick masonry prisms compressive strength and shear bond strength of brick masonry triplets. But, I cannot figure out how to find Mohr-Coulomb parameters, i.e., cohesion parameter (c) and friction coefficient (µ).? Thank you.
Relevant answer
Answer
I think my last project should be interesting for you:
  • asked a question related to Concrete Material Technology
  • asked a question related to Concrete Material Technology
Question
50 answers
Plenty of researches are focusing on geopolymer (e.g. alkali-activated fly ash) concretes, and review articles have claimed their advantages over OPC concrete. However, they've not been widely utilized in practice. Here comes the question, what are their disadvantages which limit their application?
Relevant answer
Answer
Limitations for large scale application is the organisation of the supply chain.
Think about building with OPC. You go to local supplier and buy a bag. That's it.
Geopolymer requires for the moment higher know-how on site.
Geopolymer is a decentralized production with local knowledge, compared to cement production where you have centralized production and embeded knowledge in the bag (you just need to add water afterward).
  • asked a question related to Concrete Material Technology
Question
5 answers
What are the bacterial species used in bio-concrete and what are the chemicals used in making bio concrete?
Relevant answer
Answer
Bio concrete is a special type of concrete which can heal itself with the help of bacteria. It is also known as self healing concrete or bacterial concrete. Bacteria belonging to genus Bacillus are usually used in bio concrete, which includes Bacillus cereus, Bacillus cohnii, Bacillus halodurans, Bacillus pasteurii, Bacillus pseudofirmus, Bacillus sphaericus and Bacillus subtilis.
Please see the following RG links and PDF attachments.
Good luck!
  • asked a question related to Concrete Material Technology
Question
2 answers
i m modelling a 2D beam in abaqus, the model is nonlinear . i want to study the crack propagation and its mechanisms due to applied load .
in material section(in abaqus) i have used the concrete damaged plasticity, i want to know about the tension stiffening and its damaged
plz provide with some solution would b a great help
thanks
Relevant answer
Answer
The two final papers in the attached list attached can be used
  • asked a question related to Concrete Material Technology
Question
5 answers
How can the Cole-Cole curve of an asphalt binder be plotted? The high and mid temperatures are from the DSR, but where to obtain the low with phase angle data? The BBR doesn't throws any result in terms of the phase angle because it is a simple flexural test.
Any references on how this can be done?
Relevant answer
Answer
I need your help, I am trying to build cole cole diagrams from de E*, how can I get E' and E"? or how can I get the G parameters to build this Cole - Cole diagrams?
  • asked a question related to Concrete Material Technology
Question
27 answers
As we know water absorption of RCA is more than the natural aggregate...so how do we manage it in case of partial replacement..
Relevant answer
Answer
Interesting discussion!
  • asked a question related to Concrete Material Technology
Question
8 answers
I have a problem of a test setup to do the direct tensile test in a universal testing machine. The machine jaws cannot be applied directly to grip the test specimens because of local damage and slip around the jaws. I want to  do a fabrication by attaching metal plates to the specimens and my problem is what kind of adhesive of sufficient bond strength  will I use to bond the plates to the concrete?
Relevant answer
Answer
Alex,
Your problem is bigger than you think. Concrete is not like metals. Not only do you have to worry about getting a grip on the sample, because concrete is such a brittle substance that gets more brittle as it gets stronger, you also have to take care not to introduce extra moments through misalignments, potentially in both x and y, that can lead to inconsistent or erroneous results. Something like the opposite of loading a compression sample through a ball is needed. I suggest this can be done through chains or cables depending on loads, attached to plates glued or bolted to your specimens. Be very careful because such attachments can fly around at failure. Even with such a system, aligning the top and bottom along the intended axis is also necessary. For this I sometimes used two lasers.
Direct tension testing of concrete is very hard. If you are looking for loading curves going from zero through the peak and back to zero, it is even harder than that. As always, the question: why do you want this value? Maybe the question is already answered. Maybe there is another test to get you the information you need, Brazilian or flexural test perhaps.
  • asked a question related to Concrete Material Technology
Question
13 answers
The surface chloride content data is missing, but the concrete was ponded with 3% NaCl solution for 30 days.
Relevant answer
Answer
Petr Konečný, Can you provide an example of the whole process? An excel sheet maybe?
  • asked a question related to Concrete Material Technology
Question
3 answers
Type III cement is generally preferred for High strength development, and are usually finer than the OPC/Type I cement. In India, which type of cement is classified under Type III?! Whether OPC 53 grade belong to this category?
Relevant answer
Answer
The ASTM has designated five types of portland cement, designated Types I-V.  Physically and chemically, these cement types differ primarily in their content of C3A and in their fineness.  In terms of performance, they differ primarily in the rate of early hydration and in their ability to resist sulfate attack.  
pl. follow the link to compare the properties
  • asked a question related to Concrete Material Technology
Question
10 answers
i am doing my final year project so i am looking on ways to improve the strength of recycled aggregated concrete and increased the percentage of recycled aggregate used without compromising the strength of concrete.
Relevant answer
Answer
"Aggregate" has no strength! It is "loose" and can be disrupted by hand or foot. Aggregate is a filler which is used in concrete to save money, because the client would not be able to afford using concrete made only with cement and water, also known as grout.
Using appropriate concrete mix design criteria, adequate concrete strengths should be achieved, even for "poor" course aggregate. The only caveat would be if poor quality fine aggregate should be used, in which case relatively more cementetious materials would be required per unit weight of the concrete, and also concrete shrinkage would become a serious factor to be considered and controlled.
The simple answer is that the "strength" of recycled aggregate is what it is, and cannot be "increased", except by reducing the amount of the recycled aggregate used in the Mix and provided that the course aggregate is not actually a mudstone or similar which could disintegrate during production of the concrete.
  • asked a question related to Concrete Material Technology
Question
2 answers
Although modified VSI test with 0.5 increment rate was used in several studies, there is no any accessible document to evaluate visual segregation of SCC. 
Relevant answer
Answer
Thank you Sina Dadsetan for your answer. I cannot access that standard from my university. I have ASTM C 1611. My question is related with increment rate of VSI not cone orientation. I think the standards refer the same VSI rating values (0, 1, 2 and 3). But I want to express the values with 0.5 increment rate as 0.0, 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0. I cannot find any materials (article, report etc.) for the rating. 
  • asked a question related to Concrete Material Technology
Question
6 answers
Although VSI test is commonly known as static segregation evaluation method for self-compacting concrete, it is rarely expressed as dynamic segregation method in some studies. Can the both phenomenons (static and dynamic assessments) express  with the test method.
Relevant answer
Answer
You may be interested to hear that I investigated an example of severe static segregation where, in the worst case, coarse aggregate had sunk over 5m from the top of a 55m deep pile (not true self-compacting concrete but high flow concrete that consolidates under its own weight with no vibration). The site records showed no evidence of dynamic segregation problems through VSI in any of approx. 300 batches.
  • asked a question related to Concrete Material Technology
Question
6 answers
I have a mix design of cement flyash blend. After doing rietveld refinement I have found that the ettringite percentage that was 1.57% at 7 days reduced to 0.85% at 28days. The gypsum content that was 0.67% at 7 days increased to 2.52% at 28days. Not sure, if I have identified the peak of gypsum correctly. Based on the past literature, ettringite normally converts into AFm phase but not back to gypsum.
I am quantifying the samples using external standard method and value of factor "G" which i'm using is 1890.29. The formula, which i'm using for the calculation of phases is (S * ρ * V2 * µ)/G. Where S=scale factor; ρ = density of a particular phase; V2= square of the volume of unit cell of the same phase; µ = absorption coefficient of the mix.
The scale factors were:
Ettringite @ 7day =  0.00000632                Gypsum @ 7day = 0.00004583
Ettringite @ 28day = 0.00000341               Gypsum @ 28day = 0.00014414 
Ettringite density = 1.79 g/cm3 and unit cell volume = 2306.04 pm3
Gypsum density = 2.32 g/cm3 and unit cell volume = 493.34 pm3
µ = absorption coefficient of the mix = 49.29 cm2/g
The data was collected at Brukers D4 Endevor with the following settings:Cu ka Anode, Stepsize 0.013 deg, time per step 1 sec, 40 Kv and 40 mA
I have attached the jpeg images of the refined samples for both 7 and 28days and have also attached .raw files. I would highly appreciate if someone could have a look and suggest if the identification is correct or there is something wrong in that.
Relevant answer
Answer
I think that the issue is mainly a phase misID. Since you have calcite in your system, its quite likely that the peak that you're assigning to Gypsum at latter ages corresponds to hemicarboaluminte or monocarboaluminate (both are AFm phases), both have their main peak around this position. In fact, the main peak of Mc matches perfectly your data, as you can see in the attached image (you've not only one Mc peak, but all of them, always remember that a good phase ID require the presence of all the main peaks of the candidate phase, unless you suspect strong texture). Hope this would be helpful for you :)
  • asked a question related to Concrete Material Technology
Question
9 answers
Like Bogue's equation for compound composition (C3S, C2S, C3A and C4AF) estimation of Portland cement based concrete, Is there any method/equation available for the estimation of the same for fly ash? 
Relevant answer
Answer
Dear Lincy,
There is no need to estimate quantities of "C3S, C2S, C3A, C4AF" in fly ash because there are no such minerals in fly ash. Fly ash consists of mostly amorphous phases. Ideally, the major component is amorphous silica (in class F fly ash). Usually, some content of lime (CaO), which in class C fly ash can be high. Maybe some alumina, sulfate, and alkali. You may have some minor contaminating compounds too. As crystalline phases in fly ash, you may have mullite and quartz in relatively small amounts (depending on the source of fly ash), but most phases are amorphous (that is why you will not be able to identify them by XRD). The most important components from the viewpoint of cement reactivity are amorphous silica, lime, and alumina. I hope this will help you.
  • asked a question related to Concrete Material Technology
Question
4 answers
What is the best size particles to be used from glass to replace the fine aggregates in self compacting concrete?
Relevant answer
Answer
thank you very much brother
  • asked a question related to Concrete Material Technology
Question
2 answers
I have to interpret result of measurements of thermal properties of concrete made with use of ISOMET 2104 equipment. These results are strange: thermal conductivity is higher than expected and specific heat is lower. Is this equipment suitable for testing such a non-homogenous material as concrete?
Relevant answer
Answer
Thanks for your message.
With my pleasure to study that in details. I think the brittleness of rock shall be taken into account. This issue is handled in concrete by using steel bars or fibers.
  • asked a question related to Concrete Material Technology
Question
3 answers
I am in a site where I cannot economically obtain other suitable aggregates for making concrete.
Relevant answer
Answer
additional to Dr Prunell: Coarse aggregate grading can be preffered coarser to decrease the expansion levels in long term as seen the results of study given below. The method can also be decreased paste volume necessary with decrease of total surface area according to similar consistency and get economy.  However the fresh mix can be tend to harsh mix, so it must be checked
0.075-5 mm size portion of aggregates that more tends to ASR may be decreased and 0-0.075 mm can be increased . Because reactive aggregates generally works as pozolanic materials below 0.075 mm in long term. So there is no need extra cementitious materials such as silica fume etc.
  • asked a question related to Concrete Material Technology
Question
2 answers
please
dr
I HAVE NO GAP STILL
Relevant answer
Answer
Dear  DR. BASSAM
HOW ARE YOU
THANK YOU FOR YOUR REPLY
PLEASE I AM DOING PHD IN MALYSIA BUT STILL I DO NOT HAVE THE GAP FOR MY STUDY 
(REPLACEMENT OF WASTE GLASS IN SELF COMPACTING CONCRETE)
PLEASE IF YOU HAVE IDEA ABOUT THIS TITLE
  • asked a question related to Concrete Material Technology
Question
6 answers
PLEASE my question about the size of particles and proportion and w/c
what is the best to proceed
Relevant answer
Answer
HELLO  DR.
Thank you so much for reply
so you encourage me to study the ASR...
  • asked a question related to Concrete Material Technology
Question
8 answers
I HAVE checked ordinary concrete
as size particles 
propotion
and type of glass
w/c ratio
Relevant answer
Answer
 Dear Dr Khaled
I'm here to help you.
The gap you are looking for is :"Utilization of waste glass at optimum amounts in concrete production not only provides significant environmental benefits such as reducing carbon dioxide emissions generated during the production process of cement but also enhances performance of the concrete and cement."
Please see my article and you will be satisfied.
  • asked a question related to Concrete Material Technology
Question
6 answers
Cement mortar gains strength with time due to chemical reactions involved and formation of C-S-H gel but how bond between aggregate and mortar takes place specifically.
Relevant answer
Answer
Bond strength comes from the interlocking of the aggregate surface with the hardened cement mortar. The bond strength will therefore depend on the surface texture and the strength of the aggregate. A rough texture will give a higher bond strength than a smooth surface texture. The bond between an old mortar and  a new mortar comes from this interlocking mechanism and not from a reaction between an old mortar surface and a new mortar when these are used.
  • asked a question related to Concrete Material Technology
Question
5 answers
In an FTIR analysis of cementitious materials (Fly ash and cement combination) from 3 hours to 28 days of hydration, the peaks were identified only at upsilon (2&3) vibrations of H2O. No other peaks were observed at any other region (for eg. corresponding to Ca(OH)2). What could be the possible reasons?! or only two peaks should be expected for such a study?! 
What do the bandwidth shift and increase in peak intensity of an FTIR spectrum of cementitious materials indicate?!
Relevant answer
Answer
But they were recorded using an ATR?
  • asked a question related to Concrete Material Technology
Question
4 answers
I have just finished casting 36 geopolymer mortar mix designs. Several variables were set in my work. Nanosilica replacement dosage (0, 2, 4% of slag weight), microsilica replacement dosage (0, 5, 7.5 and 10% of slag weight), chemical activator type (2 types), solution to base material ratio (2 levels).
I am asking about the best approaches to determine optimized mix designs for further tests.
In the first stage the compressive strength and flowability of mortars were evaluated.
best,
Relevant answer
Answer
Once you have made trial mixes and tested the required responses such as compressive test and other tests of interest ,you can then apply surface response methodology to optimize the mixes otherwise you will be forced to conduct several tests to come up with an"optimized mix"
  • asked a question related to Concrete Material Technology
Question
6 answers
Shall we used as a cement replacemet?
Relevant answer
Answer
Dear Dr. Saidani:
Thank you very much for your feedback on my comment. It is possible to get 30-35 MPa (with cement content - 340 kg/m3, W/C = 0.45 - 0,5). Note that we have investigated recycled concrete made with brick aggregate. You may get more detailed information from the following reference:
 Mohammed, T. U., Hasnat, A., Awal, M. A., Bosunia, S. Z., (2015). “Recycling of Brick Aggregate Concrete as Coarse Aggregate”, Journal of Materials in Civil Engineering, Vol. 27, No. 7, July 2015, CID: B4014005,(doi:  http://dx.doi.org/10.1061/(ASCE)MT.1943-5533.0001043).
Thank you.
  • asked a question related to Concrete Material Technology
Question
7 answers
i m working on self compacting mortars and i have issues about them :
1.       by which standard code I can find self-compacting mortar’s mix design?
2.       What’s the appropriate range for these proportions in self-compacting mortar? water/cement?
Cement/powder? Water/ powder?
3.       Which standard code should be used for aggregate size grading in self-compacting mortars?
Relevant answer
You can find in research gate site two papers about the subject that can help you to come to your conclusions about your questions:
Methodology for mix design of the mortar phase of self-compacting concrete using different mineral additions in binary blends of powders
Methodology for the mix design of self-compacting concrete using different mineral additions in binary blends of powders
Good work
  • asked a question related to Concrete Material Technology
Question
5 answers
i want know to calculate the bleeding rate for any mix design. 
1) with only cement =307 kg/m3 2) with cement and flyash =210+95 kg/m3 
Aggregate ratio FA/CA=0.6 and FA/ total Agg.=0.38
three cement having C3A<3% , 4-7%,and >8%
Is there any mix design following above parameters from which i can get good data to measure bleed rate evaluation for my project?
Relevant answer
Answer
Hi Bhupesh, You pretty much need to separate the bleed water and measure its mass over time to calculate the bleed rate. You also need to account for any evaporation during these measurements. Please read more in this article: https://link.springer.com/article/10.1007/BF02480511
  • asked a question related to Concrete Material Technology
Question
14 answers
concrete mix are of many types ,generally for domestic construction we use M20 grade of concrete where 'M' is the mix
of ingredients such as cement, agrregates(fine and coarse) and water and '20'refers to compressive strength of concrete for 28 days of curing with water.
steps invovlved in concrete mix are
1)collecting raw materials such as cement (43 grade or 53 grade),fine agrregate(sand)and coarse aggregate(gravel or stone)
2)batching:-weighing of all the raw materials the ratio of M20 grade of concrete should be (1:1.5:3) which means 1 part of cement,one and half part of sand and three parts of gravel with water by water cement ratio.
3)the water cement ratio should be 0.45 of all mix
4)mix the all ingredients such as cement ,affregates and water.
5)after mixing the freshly mixed concrete should be used for its application .the initial setting time of concrete is 30 mins and final setting time sholud be less than 10 hrs.
so this was about the mix design for M20 concrete.
Relevant answer
Answer
Thank you very much for replying Dhirendra Singhal . This information of yours is really helpful. Also, thank you very much for your inputs.
  • asked a question related to Concrete Material Technology
Question
17 answers
high strength concrete can be obtained by using a wide variety of mix proportions if proper mix design procedures are used.
recommended mix proportions for high strength concrete?
Relevant answer
Answer
Thank you very much for replying Sushanta Roy sir. This information of yours is really helpful. Also, thank you very much for your inputs.
  • asked a question related to Concrete Material Technology
Question
10 answers
In the calculation of the water/cement ratio and of mix proportions in general, the volume of the liquid superplasticizer must be taken into account.
Relevant answer
Answer
Thank you very much for replying Saad Sarsam. This information of yours is really helpful. Also, thank you very much for your inputs.
  • asked a question related to Concrete Material Technology
Question
8 answers
One of the most important component in hydraulic cements is calcium di and tri-silicates-based cement, which is widely used as building and construction material. There are three main compounds in the cement: dicalcium silicate (C2S), tricalcium silicate (C3S), and calcium aluminate (C3A). Highly crystalline calcium hydroxide (Ca(OH)2) and amorphous calcium-silicate-hydrate (C—S—H) are the principal phases formed in crystallinity and the hydration of calcium silicates (C2S and C3S). The paste form of hydrated cement slurry mostly consists of C—S—H and calcium hydroxide (CH). Additional phases including sulfoaluminate and secondary phases are formed. Since calcium hydroxide component (CH) is soluble in water may cause low strength. It has been reported that mechanical properties of cement are improved by reduction of CH and addition of SiO2 (S).  Biocementation is a process to produce binding biomaterials to act as cement. Such phenomena is created by a mixture of calcium-silicate-hydrate gel mixed with hydroxyapatite. In biocement composition, calcium silicate hydrate has been reinforced with co-precipitated particles of hydroxyapatite. Biocompatibility of such biomaterial is also enhanced due to absence of aluminum and magnesium in the composition of biocement. The biocement is suitable for variety of applications including dental implants, bone fixation, and bone repair. In fact, biocement is a mixture of mineral oxides once it hydrated crystals are formed. Such biomaterial are originated from living organism calcinates and silicates are as by-product of living organism or even biopolymeric materials are produced. Biocement production has extensively progressed as it is considered as green biomaterial. Environmental demand and use of biocement for stabilization of soil is in an extensive recent research growth of waste conversion to desired biomaterial.
Relevant answer
Answer
Thanks Seyed
Our target is to produce EPS bio-polymers; in fact we did; we need to identify the potential organisms using PCR!
Regards
  • asked a question related to Concrete Material Technology
Question
2 answers
Internally cured concrete has been shown to be effective in reducing the potential for plastic shrinkage cracking of pozzolanic concrete mixtures like Fly ash. Anybody found its significance in the case of high volume replacement by slag?
Relevant answer
Answer
I found your question rather puzzling.
First, internal curing does not reduce chemical shrinkage. In fact, it even increases chemical shrinkage, since it increases the degree of hydration of the cement (in low w/c mixtures). Perhaps you meant autogenous shrinkage instead.
Second: why are you mentioning "freezing areas" in the main question when you are then speaking about plastic shrinkage cracking in the explanation?
It would be better if you clarify your question if you want to receive meaningful answers.
  • asked a question related to Concrete Material Technology
Question
7 answers
Shear critical elements experience the biaxial state of stress i.e. axial compression and transverse tension. Other than mohr-column theory, please suggest me some failure theories, which considers both states of stress. 
Relevant answer
Answer
Thank you very much, Sir
  • asked a question related to Concrete Material Technology
Question
5 answers
OM-SEM analysis on a 10-year old concrete pavement in a bus stop have shown serious damage due to AAR. It turned out that the aggregates responsible for the formation of expansive products (both amorphous gel and microcrystalline phases) and the damage are serpentinite/greenstone/greenshist. There is clear evidence for reaction between the pore solution and some mineral phases (e.g. Ca-Mg amphibole, serpentinite, etc.). The reactions, however, are not fully understood so far, especially because some of the observed mineral phases are being stabile in high pH environment. Has anybody seen serpentinite, greenstone undergo to AAR (ASR)? Thanks!
Relevant answer
Answer
Dear Mr. Pinter:
Please find attached a flow sheet demonstrating the supergene alteration of metabasic and metaultrabasic rocks to be published in Earth Science Reviews (2016) online and entitled:
Residual clay deposits on basement rocks: The impact of climate and the geological setting on supergene argillitization in the Bohemian Massif (Central Europe) and across the globe.
It may help you get a bit closer to a solution.
Viel Erfolg
Harald G. Dill
  • asked a question related to Concrete Material Technology
Question
3 answers
To assess the durability of concrete, permeation tests can be conducted such as air permeability, water permeability and water absorption but which permeation tests are more important in concrete? If u were to choose two out of 3, what u will choose and why? Which permeation properties are more important in concrete?
Relevant answer
Answer
Thanks you for the explanation.
so, If i want to test the water absorption and water permeability, is it necessary to test air permeability as well?
  • asked a question related to Concrete Material Technology
Question
8 answers
During the construction of a 200 cubic meters structural element, the cement which is used to make concrete (CPC 40) was depleted, so the company whose building the bridge changed the cement to CPC 30 which is the one available in the nearest town.
I have the mix design for F´c = 350 Kg/cm^2:
400 kg Cement CPC 40
957 kg Gravel ¾”
783 River sand
210 Lts Water
3.2 Lts Sikament 450
The las 28 day compression test for this mix gave us an F´c of 450 kg/cm^2 (which I believe is impossible with the mix design, so I asked for a calibration test of the concrete plant, i´m still waiting for the test results).
I know the mix design is not good, we have experienced severe bleeding due to the over use of the add mixture and the excessive mix water, the company who’s building the bridge won’t change the mix design because they have to pump it 64 mts, but that is another topic.
My question is does this mix design will satisfy the F´c = 350 Kg/cm^2:
410 kg Cement CPC 30
957 kg Gravel ¾”
783 River sand
210 Lts Water
3.2 Lts Sikament 450
CPC 40 means that the cement paste has a minimum compressive strength of 400 kg/cm^2 at 28 days, so CPC 30 will not achieve the same strength at 28 days, so if I the mix was designed with the ACI 211.1 how can I take the change in cement paste strength and adjust the mix.
Thank you very much
Relevant answer
Answer
The earlier answers provide generally good points based on common knowledge. But the question is what is the difference between your cements PC40 and PC30. Yes, PC 30 is a lower class, but what makes it so? It sounds like these are Mexican cements. I am not so familiar with these. Is PC30 ground coarser? is it blended with a high proportion of limestone filler or slowly reactive fly ash? why is it a lower class? Knowing the answer can allow you to use it adequately to reach the strength you desire. Beyond that, while the strength depends on the type of cement, it depends greatly on the mix design. So You cannot just say we can't change the mix design because we need to pump. You can pump low w/cm concrete if you design it properly and achieve high strength. We pump concrete hundreds of meters in altitude in hot weather and achieve in excess of 100 MPa. As an engineer, you shall enforce the proper sequence of approving the mix design for your project, which includes proper mix design, testing trial batches and verifying that you meet all performance requirements. Do not get mislead by the general answers you got here. A new cement can influence rheology, setting time, strength development, and many other performance issues. You need to test your own mix in the lab and do a trial pumping in the field. Do not trust short cuts.
  • asked a question related to Concrete Material Technology
Question
5 answers
There are several characteristics that make it possible for mortars to be injected, like low setting time etc. also I want to know about these characteristics as well. Are there any codes or Standards for that?
Relevant answer
Answer
Dear Amin, 
Geopolymer is fundamentally an alternative binder to OPC, so I confirm you that not only is possible to use geopolymer mortar for injection, but also I already done optimizing cost that depends on type of geopolymer powders, liquid and type of aggregate chosen. 
But the most reduction about cost you will obtain using an efficent plant where produce drymix part , then aggregates and finally cheap system of filling liquids (there are several ways that work without lose liquid and time). 
I use liquids of 20 mPa of viscosity for these applications (so viscosity is very low, almost the same of water!)  ,tested on Marsh cone are completely comparable to OPC based or based on other hydraulic binders (lime,  etc). 
Costs depends also on raw materials that you have at disposal locally. If you need some indication Let me know .
Setting time is easy to modify, of course, depends on system you use (type of powders, type of liquid) and temperature in job site .
Regards 
Alex 
  • asked a question related to Concrete Material Technology
Question
15 answers
Dear Researchers
I try to modeling the diffusion process of concrete in Abaqus. I try to use mass diffusion technique but, I failed because my lack experience. Can anyone give me advice to do this simulation step by step?
Sincerely,
Wahyuniarsih Sutrisno
Relevant answer
Answer
For diffusion you need diffusion coefficient .solubility of the material and insert these value in Material menu of other->D ,other->S .in abaqus and Proceed further by taking heat transfer element  .You must also add absolute zero temperature and Gas constant in by clicking on Model. 
  • asked a question related to Concrete Material Technology
Question
21 answers
i am using rice husk ash as cement in concrete,now i am using 20% of rice husk ash in concrete, whether i  can use 100% of rice husk ash in concrete ?
Relevant answer
Answer
RHA acts as a pozzolan, so you need to have a certain amount of cement in the mixture which hydrates to produce calcium hydroxide. As RHA is almost pure silica, the optimum amount might be close to what has been used for silica fume - close to the 20% by mass of cement you are using now. Moreover, since RHA absrorbs water from the mix due to its fine pore structure, the optimum amount may also depend on the rehology of the mixture and on how much superplasticizer you want to add.
  • asked a question related to Concrete Material Technology
Question
10 answers
Hi:
I modelled this concrete reinforcement girder in Ansys Workbench with Explicit Dynamic moduler. My girder length is 27380mm, 1372mm height and 635mm width. It has got 4 bottom layers of reinforcement bars of 12mm dia. and two layers of top reinforcements of the same dia. Altogether it has about 50 bars. I gave the fixed support condition at both end face of the girder and applied only inertial load to the beam(self weight). I gave correct material properties to concrete girder and steel reinforcement. I got the error message as depicted in the screenshot attached. I doubt that I make some mistake with Analysis setting like end time, no. of cycles, time step, initial time etc. as you can see from the screen shot. Can any body please help me / suggest possible options I can try to get solve this model.
Thanks
Relevant answer
Answer
Lorenzo,
Could you pls repeat once again? i'am also facing the same issue.
looking forward. 
  • asked a question related to Concrete Material Technology
Question
4 answers
As I know the pH value of the Geopolymer concrete is about 13 on 28 days but the alkali silica reaction and expansion on the Geopolymer concrete is very less as compare to OPC. Am I right? If I am correct then how could it happen?
Thank you in advance
Relevant answer
Answer
Hello Shree, 
As you have seen in previous comment, studies about alkali activated materials (slag, fly ash or other, also opc cement could be used for that systems) have already done and Dr. Shi has given a very complete sommary and articles. 
But if I have correctly understood you are asking what's the difference about alkali aggregate reaction between geopolymer concrete and Portland concrete, so things are quite different, because first of all geopolymers aren't alkali activated materials, at all! 
This is a big mistake that often creates confusion...the most important reason because in geopolymer concrete alkali aggregate reaction doesn't occur is because all alkali content is inside, involved chemically in geopolymer matrix, that is a very organized reticule, so there isn't free alkali on surface of concrete that may react with silica.
Search on geopolymer institute site (geopolymerinstitute.org) the paper dedicated to this topic and please take a look at the videos that Prof. Davidovitz dedicated to clarify this big difference (these video are also in YouTube) . Remember geopolymer isn't alkali activated materials, I created geopolymer products using acids, or also with neutral pH...look also at geopolymer camp field you will find me and my russian collegues speaking on geopolymer concrete for 3d printer, if are you interested to know more. 
I usually found pH value of hardened geopolymer concrete but also of geopolymer mortar, of about 8,5-9 (hardening at room temperature), so If you use correct mix design (other topic that creates misunderstandings with alkali activated materials) and if you reduce as possible also amount of extra water, you will be sure that shrinkage will be very little or nothing and your surface will be safe about alkali aggregate reaction. 
Hoping to be useful. 
Regards 
Alex Reggiani 
  • asked a question related to Concrete Material Technology
  • asked a question related to Concrete Material Technology
Question
5 answers
Dear all,
I have the parameters of my Herschel-bulkley model for fresh concrete.
tau=tau0+k*gamma^n
and I want to model a valve.
In OF the tau0 and the k parameters in the transportPropertyDict should be diveded by the density while the exponent n should not be divided, correct?
Than another parameter nu0 (a viscosity) is requested. What is it's phisical meaning?
I have seen that if I put a value, let say 1e-3, in each time step the nu field is 1e-3 and not calculated according to the Herschl-Bulkley model.
Some suggestions?
Franco
Relevant answer
Answer
Hi !
Yes, the coefficients k and tau0 are indeed divided by the density, while the parameter n is not.
To your second question, nu0 corresponds to the viscosity under very low strain-rate. To obtain a solid-like behavior under low strain-rate, this value should be set as large as possible.
Best,
  • asked a question related to Concrete Material Technology
Question
6 answers
Grinding agents used in the production of OPC are now very much a common practice, Can these grinding agents contribute to an accelerated setting time when blended with limestone dust?
Relevant answer
Answer
Could you suggest an additive/admixture to reduce the alkalinity of the concrete to help extend the setting time if the alkalinity of the cement was higher than normal that was causing the mix to flash set as a result?
  • asked a question related to Concrete Material Technology
Question
7 answers
most of the codes and service life literature provide model for chloride based degradation however i couldn't find any model for sulphate based degradation especially sulphuric acid degradation in sewage system. only reliable equation and formulae is given by pomeroy in 1974. any latest development in this field.
Relevant answer
Answer
Dear Ankur Bansal,
 I agree with Marcos de Oliveira Valin Jr. There is very less number studies available on modelling on sulphate attack on concrete.The reactions which are taking place inside the concrete has been studied as a life models such as phenomenological isotropic damage model, which describes the material degradation. The reactive-diffusion model and the mechanical model have been implemented in a finite element code and used to simulate the experimental tests concerning ESA were studied.  
I have attached an article, which will give you glimpse on modelling. 
  • asked a question related to Concrete Material Technology
Question
4 answers
For different tests we get different value of characteristic compressive strength.IS456 -2000 recommand 15cm Cube strength where as ASTM Recommand the cylindrical strength.
Relevant answer
Answer
As per IS code the compressive strength of 150mm cube is tested, and the characteristic strength of cube is tested at the age of 28 days, not more than 5% result of the strength beyond the limit. ratio between the cylindrical strength and cubical strength is equivalent to 0.8 for up to M40 or M50 grade of concrete, where as if the grade of concrete is M80 or above this ratio will increase, and for concrete above M100 grade the ratio become unity.
As per RILEM, the strength of two different shape of concrete can not be compared, and the same is written by A M Neville in his book Properties of Concrete.
  • asked a question related to Concrete Material Technology
Question
4 answers
Chemical treatments such as alkaline, saline-treatment has been experimentally proven to improve the mechanical properties of natural fibers. However, drawbacks to the treatment includes shrinkage of diameter and length. This affects the aspect-ratio of the fiber. Though the interfacial bond increases and there's a higher possibility of greater adhesion between the fiber surface and concrete matrix, the high aspect ratio will, I assume, decrease the mechanical properties of concrete? I have yet to read articles using chemically treated natural fibers in concrete mix so if anyone has any recommendation, please do drop a quick comment.
Relevant answer
Answer
Dear Sheikh,
Based on my experience with reinforcing material, chemical treatment can improve mechanical properties of natural fibres up to 20% (Chuah, 2015). The trick for a better improvement rate depends on the careful preparation of samples.
For your references: (I got problems uploading this doc...have been stuck on this thread for 10 mins. If you need the pdf copies, message me for them)
1) Nano reinforced cement and concrete composites and new perspective from graphene oxide.pdf
2) Developments on vegetable fibre–cement based materials in São Paulo, Brazil an overview.pdf
3) Chemical treatments of natural fiber for use in natural fiber-reinforced composites: a review.pdf
  • asked a question related to Concrete Material Technology
Question
5 answers
Thin cement grouts with high water cement ratio of more than 1 involve bleeding and consequence poor quality pastes. In some cases channels will form in the paste which increase its permeability and decrease its strength. I want to know that what would happened during this type of bleeding (known as Channel bleeding). 
Relevant answer
Answer
Generally, channel bleeding occurs due to low cement content or due to high water cement ratio. In your case , this happened due to HWCR, During this channel bleeding the extra water which will carry very smaller particles ( may be cement ) . which increases the porosity and decreases the strength of the concrete.
  • asked a question related to Concrete Material Technology
Question
5 answers
I need to continue advancing my research on concrete strength.
Relevant answer
Answer
Hi Claudia Viegas,
Yes, the next stage is to use Principal Component Analysis (PCA) for to get more  condensate data.
Thanks for your comments.
Best regards,
Fabiane
  • asked a question related to Concrete Material Technology
Question
7 answers
 I need references depths of carbonation or carbanotacion constants (speed carbonation ) of concrete made with blended cements with limestone filler . any reference ?
(Xco2=kco2 (t)^(1/2))
Relevant answer
Answer
Dear Colleague.
I send you this paper
  • asked a question related to Concrete Material Technology
Question
8 answers
I am modeling a post tension slab using unbonded system .. please if you have any information or any data to use them in my model specially in the contact definition
Relevant answer
Answer
Be careful with the local damage due to the concentrated load at cable-concrete slab contacts. The pre-load should be distributed to surrounding the contact area instead of a point.
  • asked a question related to Concrete Material Technology