FAQ

Shawn the Expert

 

Shawn Byrd is a Technical Manager at Tinius Olsen Testing Machine Co. in Horsham, Pa. Shawn is also a member of the Tinius Olsen M.A G. or Market Analysis Group, which has responsibility for market analysis in relation to Tinius Olsen’s position in the marketplace. Shawn is a member of the following ASTM International Committees, D30 on Composite materials, E28 on Mechanical Testing and F16 on Fasteners. These groups have over 900 members combined and are responsible for 204 standards. Shawn is also involved with ASTM working on collaborative projects with colleges and professional industries. Shawn has been involved in testing labs in the US, China, India and Singapore. During his tenure in the US Navy, Shawn completed his degree in Electrical Engineering.  Shawn has completed studies in both the mechanical and material science arenas as well. Shawn has completed and taken part in numerous Nadcap, A2LA and ISO audits.  As a technical manager at Tinius Olsen Shawn focuses on materials testing and the application of various standards to different testing platforms to assist in the evaluation of materials and products.

  • 1.Construction FAQ
  • What is the toughest grade of concrete?

    admin29-01-2016

    Whereas the grades of concrete commonly used have strengths varying  from 15 to 35 Mpa, but for special purposes special concretes are manufactured. They include the use of silica fume, fibre reinforcement and polymers. Concretes having strengths upto 125 Mpa have been produced to the best of my knowledge. As you can imagine these records are broken every now and then.

  • What is the range of slump for ordinary design mix and pumpcrete design mix?

    admin29-01-2016

    Regarding the Slump – normal concrete slump is about 2 inches (50 mm). For Concrete that need to be pumped, these values are about 4 to 5 inches that is 100 to 125 mm. These values depend on the amount of sand and size of aggregates in the mix. Some guidance is given in the table below.

    Recommended Slumps for Various Types of Construction

     

        Concrete Construction                                                     Slump (in inches)

                                                                                                                     Maximum               Minimum

    1. Reinforced foundation walls and footings                          3                           1
    2. Plain footings, caissons, substructure walls                        3                           1
    3. Beams and reinforced walls                                                 4                           1
    4. Building columns                                                                 4                           1
    1. Pavement and slabs                                                          3                           1
    1. Mass concrete                                                                   2                           1

     

    For Concrete Mixes that are to be Pumped

     

    Maximum Size of Aggregate                     9 mm     18 mm   25 mm   37 mm     37 mm

    Percent of Sand                                         60          43             45           39             40

    Cement (Pounds per Cubic Yard)               565          525            525        510           565

    Slump, inches                                             4          3 to 4           5          3 to 4      3 to 4

  • What is the difference between concrete and mortar?

    admin29-01-2016

    The difference between the concrete and the mortar is due to the size of aggregates present. Whereas in mortars we use only fine aggregates, that is sand or its equivalent, in concrete we use both fine and coarse aggregates.

    It is well known that the strength of concrete depends on the the maximum size of aggregates, beside other factors. Therefore if concrete can be used in a given situation, it should be used in preference to mortar as it would work out cheaper.

  • Tinuis Olsen testing machine load rate

    admin29-01-2016

    Q -

    I am working in laboratory as lab technician and i am using the T.O. machine in testing materials. My question is as the load is controled with a load valve, but what does the numbers indicate ie 0 to 50. The test machine is as shown below.  TINIUS OLSEN UTM 2000KN CAPACITY MODEL AC8500 S/N 106750.

    A -

    The machine you've referenced is a 400,000lbf capacity Deluxe Super L hydraulic testing machine with extra height and a low base. The machine was made in 1970 and was sold to a customer in Australia. I assume you refer to the graduations behind the loading capstan - these numbers have no significance other than as a guide to open the capstan to, to approach a similar loading rate for each test. As the hydraulic oil heats up, the loading rate will change and will need to be adjusted, so these graduations were simply there as a helpful guide for operators.

  • Testing of foundation

    admin29-01-2016

    Q -

    We are into the bussiness of Construction of Transmission Line towers, which needs a lot of concrete work. Currently our projects are running in Nagpur,Yawatmal in Maharashtra (India), Hence I was looking for an agency for testing of foundation at site. Can you do help about it ???

    A -

    Thank you for you inquiry. Unfortunately we only manufacture and sell the testing equipment, we don't perform any testing services, additionally, I'm not familiar with any independent test houses close to your projects. Sorry I can't help you further.....

  • Please explain the procedure of use of elongation & flakiness gauges?

    admin29-01-2016

    The properties of fresh and hardened concrete depend on the shape of the aggregates as well as other characteristics. The shape of three dimensional bodies is difficult to describe, it can be simplified by describing certain geometric characteristics such as the flakiness and elongation index. These are defined as follows;

     

    Flakiness Index is the percentage by weight of particles in it, whose least dimension  (thickness) is less than three-fifths of its mean dimension. The test is not applicable to particles smaller than 6.3 mm in size.

     

    Elongation Index  is the percentage by weight of particles in it, whose largest dimension (length) is greater than one and four-fifths times its mean dimension. The test is not applicable to particles smaller than 6.3 mm in size.

     

    Procedure for using Gauge for Flakiness Index

    A balance of suitable capacity, gauge for Flakiness Index and a set of Sieves of relevant sizes as  per the specified Standard  will be required.

     

    Sample size will be such that at least 200 pieces of any fraction to be tested will become available. The aggregates will be dried to a constant weight in an  oven at a temperature of 110º ± 5ºC and  weighed to the nearest 0.1g. The aggregates will then be sieved  through the set of prescribed sieves.

     

    Each fraction is then gauged for thickness through the slots of the gauge. All the pieces passing through the gauge are collected and weighed to an accuracy of 0.1 percent of the weight of the sample.

     

    The Flakiness Index is the total weight of the material passing various gauges and sieves expressed as a percentage of the total weight of the sample gauged.

     

    Elongation Index

    Similar procedure is used for the determination of Elongation Index. Sample is first dried and then sieved through the set of Standard Sieves. Each fraction is then gauged through the slots of the Elongation Gauge. The Elongation Index is the total weight of the material retained on the various length gauges expressed as a percentage of the total weight of the sample gauged.

  • I am in purchasing Saudi Arabia - could you please tell me what basic items should I be looking for in a fresh concrete test set? The QA manager here says we are testing in accordance with ASTM C138, 143, 192, 231 and 470

    admin29-01-2016

    The ASTM 138 deals with the Test Methods for Density, Yield and Air Content of Concrete

    The equipment required is 

    1. Balance

    2. Tamping Rod

    3. Internal Vibrator

    4. Measure - A cylindrical containe made of steel or other suitable material

    5. Strike off Plate

     6. Mallet

    Similarly you may look at the other standards mentioned in your letter and find out the equipment required. In case of any difficulty please do let us know. 

  • Microdeval Testing Machine - BS EN1097-1 standard

    admin29-01-2016

    Q-

    We, M/S. SAIF BIN DARWISH is the leading producer of aggregates, different sizes of rocks, road base, sub base and armour rocks for concrete, Highways, infrastructure and backfilling projects in United Arab of Emirates.

    We are in the need of Micro-Deval Testing Machine -  BS EN1907-1 standard. since you are producing wide range products, we look forward to get best offer for Micro-Deval testing machine at the earliest.

    A-

    While we do manufacturer a wide range of testing equipment for concrete, cement, aggregate, soil and asphalt testing, unfortunately, at present, we don't have a Micro-Deval Testing machine in our Product Range.

  • Is it true that the finer the grain of the concrete mix, the stronger the resultant concrete will be?

    admin29-01-2016

    It is true that the finer the grain, the higher the strength of resultant concrete. But this is only half the story. Finer grains (like those of Silica fume) help in filling up voids of concrete which are otherwise filled by air. We need higher sizes of aggregate also to get strength. The aggregates should be well graded and larger the maximum size of aggregate the smaller the quantity of cement to get the same strength. Thus for the same cement quantity, maximum size of aggregate will give a higher strength provided the aggregate is well graded.

    Thus to get maximum strength for a given quantity of cement we should have finer particles as well as higher sized particles and all aggregate should be well graded.

  • I have an old Forney type dial compression machine, can Tinius Olsen help me with a retro fit or upgrade, I need to get a digital display on the unit?

    admin29-01-2016

    Yes it can be done. Tinius Olsen can definitely help in the matter. Please send the relevant details to info@tiniusolsen.com

  • Hi I work in a lab doing QA tests on concrete cubes and cylinders, we are looking into prism block testing should I use ASTM C39 as my pint of reference? And are there any recent changes I should consider?

    admin29-01-2016

    Yes, the method given in the ASTM C39  "Standard Test method for Compressive Strength of Cylindrical Concrete Specimens" can be used for testing concrete specimens of prismatic shape. If the requirement is of compressive strength only, there are no extra precautions to be taken, other than those required normally for cylindrical specimens.

  • Do Tinius Olsen have an air Permeability unit I need a Blaine type BS 4359, the glass U tube on my existing unit has cracked and I cannot get a replacement?

    admin29-01-2016

    Yes we do make the Blaine type air permeability unit based on BS 4359. It is a fairly standard item and there should not be any problem in supplying a spare glass u-tube

  • I am a railway engineer. I am retired Dy Chief Engineer. I am now a internal consultant for railway private sidings. Some bridges are also constructed. My question is what should be the frequency of testing of concrete?

    admin29-01-2016

    To keep control on the quality of concrete produced, it is required to cast a number of specimens from random samples and test them at suitable intervals. Indian Standard IS: 450-2000 stipulates that random samples from fresh concrete shall be taken as specified in IS: 1199-1959 and cubes shall be made, cured and tested at 28 days as described in IS:516-1959. The test result of a sample should be the average of the strength of three specimens (constituting the sample). The individual variation should be no more than ± 15 percent of the average. If it is more the test result of the sample is invalid. The random sampling procedure is adopted to ensure that each concrete batch shall have a reasonable chance of being tested i.e. the sampling should be spread over the entire period of concreting and cover all mixing units.

     

    The Indian Code of Practice prescribes minimum frequency of sampling of 1,2,3 and 4 number of samples respectively, for 1-5, 6-15, 16-30 and 31-50 cubic meters of concrete being used in the job.

     

    For concrete quantity of 51 cubic meters and above, the number of samples shall be 4 plus one additional sample for every 50 cubic meter of concrete or part thereof. At least one sample should be taken from each shift. In case of continuous production e.g. ready mix concrete plant, the frequency of sampling may be as per agreement. Additional samples may be required for various purposes such as 7 days strength, accelerated tests, time of striking formwork etc.  

     

    As far as the requirements of specifications with regard to the acceptance criteria is concerned, IS: 456-2000 stipulates that the mean strength be related to the grade and the standard deviation of any four non-overlapping  consecutive test samples.

  • CLARIFICATION ON ACCEPTANCE CRITERIA AS PER IS-456

    admin29-01-2016

    Q-

    We have tested 190 concrete cube samples (190 X 3 speciments) taken during batching of concrete at batching plant from 01.10.10 to 15.11.10.The quality of ingredients like sand, aggregate,cement and water used for manufacturing concrete were of same quality. The concrete mixer is having capacity of 0.5 M3. My questions are :

    Q No. 1. How I shall identify a 'Batch' of concrete.

    Q No. 2. While calculation Standard Deviation, test result of first 30 samples (acceptable as per Cl. 15.4) have to be considered (say sample no.1 to 30). For calculation S.D. for next 30 samples (sample no. 31 to 60) shall I consider only 30 samples or 60 samples (sample no.1 to 60) together and so on.

    Q No. 3.As per Cl. 16.1 a) Mean strength from any group of four cubes (ammendment no.3) have to be considered :- From where shall I start grouping ? shall I satrt from start date like 1-4,5-8,9-12 etc. ? Please clarify.

    Q No. 4. Suppose sample no.1,2,3 (01.10.10) are from individual foundations and 4-10 (02.10.10) are from one single foundation and 11-16 (03.10.10) are from another single foundation. Grouping is made taking 1-4, 5-8,9-12 ,13-16.Now, if group 1-4 fails (as per Cl.16.1a) but 5-8 passes then what will be the fate of the single foundation (sample no. 4-10).

    I shall be oblised if you kindly clarify my doubts.

    A-

    Q.No.1 “Batch” theoretically means the quantity of concrete mixed at one time. But for the purpose of Quality Control, we do not have to test every batch of concrete. The frequency of sampling and how to ensure that the samples are representative is described in Clause no. 15.2.

    Q.No.2 The Clause 15.4 means that we have to cast three specimens of concrete from each sample. (Please notice the difference between samples and specimens). The three specimens are to be tested at the same time. If the results of all three specimens are within 15 percent of each other, then the test is valid and the average value for that sample should be recorded. If not, the results of thissample should be rejected. In case, the Specifications say that the Standard Deviation of 30 samples is to be calculated, then these have to be 1 to 30 and 31 to 60 and so on.

    Q.No.3 From the averages of four, it is implied that they can be any four consecutive samples, that is 1 to 4, 2 to 5, 3 to 6 and so on. The acceptance criterion is given in Table no. 11 of the same code.

    Q.No.4 If there are doubts regarding the integrity of the structure, we should resort to Non Destructive Testing. The suggestion in such cases is, that since the correlations between Rebound Hammer Values and the Ultrasonic Pulse Velocity depend on the quality of sand, cement and aggregates, the tables and charts given in books or manufacturers are not very reliable. If we carry out these tests every time we conduct a compression test, we can have our own data base which is based on our own cement, sand and aggregates. We can then use this data base with confidence. Some of the results going out of specified limits does not spell disaster and does not mean replacement of concrete. Structure should be tested in such cases.


 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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