Troubleshooting with Concrete
Contents
1. SS End of Presentat Gee DD 7 yy DE a a DE a a DE a a DE a a PE Th a a GH lt Q NN attention OUT ankyou for y S amp amp amp amp a Q a a a a GI NG a Z y 1 dis l a a amp a a 7 Z JJ a NG MS a a a a amp a a a amp a HD GI NG Yi Yy A Yi Yy Wy JA Wy Yy Ys Yy A hy a Pi 7 Pi 7 Fi Pa 92. Be wary of additional bleed due to placement over a non absorptive subgrade tu aat g 7 Ensure the surface is protected from drying conditions aft adi gt GJ R MA Apply even con inuous curing asap at JM Ka il fl fl 7 il 7 ji i pa Z ai Ly SS _ Cracks which occur in the first fer i a F Ni a ji 3 e EV Q Q SE SE Q il p zi r MOS Q Remember to dampen the subgrade and forms during hot weather Ga NA Q t commo f h m Q Q nit YA a _ Q 1 flat 0 watch out for Erect wind breaks and N avol amp _ ri even CO Wa id placing f ntin lt lt a CO DE _ C oh no HA uous curing as a NA amp work un Wy 7 Q soon INE S Jer condi ticeable until the next da 7 di a x oncrete on hot windy days _ _ spray aliphatic alcoh as possible 3 Zi 7 amp NN amp tions of jumah ASS _ 7 S amp S 8 SS _ ol on the surface NA f NA Ye a F ANE Q 8 SE RE SE EL g My a zili i vii zi ui SS _ _ SS
3. GM I _ approp Prevent Q SG amp N caling Dust Cracking ate s1 r J SS SSS i O Gi te prac tic SS Q amp Q GS Q Q SS ik Mee amp amp ld Mee SS amp Gia Concrete Scaling we Scaling blistering delamination 1s when the outer surface of the concrete peals or pops off in a thin layer the depth of the defect is shallow it typically occurs under conditions of high surface evaporation Things to watch out for Don t allow the surface to dry out This may form a skin under which bleed water and air can become trapped Don t add water to the surface during finishing This may re hydrate the past but leads to separation from the underlying concrete Protect the surface from drying out and apply even continuous curing asap C Dusti Vig Concrete Dusting Dusting i IS characterised by the appearance of a fine powder as the surface wears under very light loading conditions i i y the defect is limited to the outer su rface of the concrete TE aa era A low cement content mixes are more susceptible KA i mon Things to watch out for ER ot ka rai 1 Do not perform any finishing operations while bleed water is on the surface
4. Troubleshooting with Concrete a Pre mix Suppliers Perspective By Joe Pietrosanto TJM Operations Pty Ltd Trading as VIC MIX FI kan kan am r ri oe oe oe oe oe SS e o e yuni C S NE Ot Tis a DE NN SG E E 7 le Fi L f ik Ma lt SS a SS a AS lt amp amp amp ch pl S In the bat j 7 Y yy j 7 1 DP EC y yy g 9 amp HD ant DP ND EC S oe J GH EC y yy yy oe lt D HD lt a lt Yj 7 D ot ju 0 V f 4 O G UG x De Yj x E Vi a i Ww 7 J amp S D a amp J ye Tendering a a i y erbal requirements a a Q G orders gt a SN lt a SS SS l i 1 e Q SS l N i av ill nts Q a SS Se wT S i a i F V 1 SS SS i SS i i EE r s N N Wy Q A Verbal Requirements Orders The majority of price enquiries are received verbally Most jobs do not have a written specification Sometimes the specification is a note on a work
5. N lt coarse aggregates G amp N Ve _ YA y improved by ZA YA Decrease in size of aggregate a var AN N a var S ncrease In roundness N a MC MAS Pumping Lightweight Significant cost savings are enabled with the use of lightweight concrete in the construction of highrise buildings However Lightweight can be difficult to pump and place successfully Two factors are the most challenging when using lightweight in high rise construction The aggregate and The vertical pumping distance Number of floors Highly vesicular porous rock Highris eC KAN a JA Typically 1600 kg m3 Pumping Lightweight The key to pumping porous vesicular aggregates 1s pre treatment at the Concrete Plant Water sprays keep the aggregate s saa The U att 1S lightweight concrete capable of Bein pumped more than 25 floors in pot muna U wn we 4 eo M ow I Pa T A Jan a 7 U ajah WAN IBM amp HWT City Road Gr 222 Russell Street Concrete Bleeding a Bleeding is the name given to the action of water rising to the top of concrete shortly after compaction Factors which affect bleeding are Rate of evaporation Consistency or slump Volume of fines in the mix Bleeding is generally reduced by An increase in temperature and the evaporation rate ie summer time A reduction in the water content of th
6. e mix An increase in the ultra fines content of the mix The use of specialist admixtures ie Air Entrainers fibres Concrete Setting Time Setting Time describes the period of time it take for the concrete to stiffen and harden Factors which affect setting time are Temperature of concrete Concrete Setting Time No of tests 300 150 Graphed temperature data based on field tests performed on concrete in the field Deg C 25 F DIAE AMEE ges e a S ME A TI ET O O Oo O Oo O Oo o Oo o o O O O O O O O ap AGE od a ae Oe ee 5 O 5 O O O G O F lt 0 O O 3 LL lt s Mean Concrete Temp s Mean Air temp 4 No of tests Concrete Setting Time Setting Time describes the period of time it take for the concrete to stiffen and harden Factors which affect setting time are Temperature of concrete Quantity of mixing water Type of cements used in the concrete The presence of admixtures Setting time is generally reduced by An increase in the concrete temperature ie summer time A reduction in mix water ie reduce slump The use of primary cementitious binders The use of non chloride set accelerating admixtures S SS amp LK SS a amp
7. ied Problems arise for the Pre mix Concrete Supplier when e requirements conflict or requirements are not practical or commonly accepted kabikity 5 uired for WOTR OS The concrete shall not exhibit any shrinkage Howed the following tolerances n t for Jo passing sv O adm duced will be avo 04 4 Ere S Xur CS ae EE ined Aggregate Grading ve or larger 3 S Sas The number and Tati be Inco V regate passing pte al 6mm sieve st ED Eh 2 N tests Tpdyge lt e ing 2 36mm YA RO ao oncrete slump See gate pass g i wW EE tthe rate of ORersing 0 3mm SIEVU AIB Cs 1S ne r truck saimes Aggregate ee 915mm to 0 075mm sieve AN pro Ja one 1 test PA AA era geregate PA o PAET S ates sp piant av han AG Slum S8regates shall at all times be dealt with in such a way th A d blacn P for Xact weight of any one size of y that the cis eed OF aggregate may be incorporated in eg e a ASE er pind ro WE Hefore ey te atcn of concrete in accord x Sh Ordance with the AW Ceeg gt Om nor batch to meet the Strength and density AYA p A design of a Contract Review The customer s pricing inquiry 1s reviewed to ensure that requirements are understood and to examine our capacity to meet them This process involves using experience and technology to meet the Customer s needs ensure that pricing is carried out in accordance with Company Policies ensuring we have the resources and capabilities to meet the requirements iso
8. ing drawing When I said 4 Meters Often the tender submission and review will take Ma se ee AN place in a single conversation which may result in concrete on site within the hour The most common problem is Misunderstanding of important project details and requirements NC Handling Verbal requirements Bey NG Enquiries are received in a modern Call Centre Computer systems control customer and project details Customer Service staff are trained to communicate effectively Typical Central Order Sales Office Computerised Systems control Customer details enquiries and orders Environment technology and training work to improve communication Written Specifications All maj Or pro ects have written specific ations The Concrete Industry sells concrete like pizza Product can be ordered and delivered within the hour The ingredients are different for each order and The problems faced by Concrete Suppliers are the product must reach the Customer while it is still fresh Securing a current and complete copy of the Project Specifications from our potential Customers Interpreting the specification and designing concrete mixes to meet all relevant requirements Completing this entire process in as short a time frame as possible Specification Requirements Specifications often contain prescriptive and performance based requirements which aim to ensure the best possible concrete is suppl
9. lating requirements that cannot be complied with and resolving them prior to acceptance Address the pro Submission for supply of Concrete x des EG requ crete qui or aa rement submit thec Submit the ly Products and pr ons for supp Prices the conditi Submit t Submit features or clarification with the adhi Submit the performance data specification Pre mixed Concrete Suppliers are continuously expanding their testing capabilities to meet Customer requirements Core Testing Air Yield Testing poe AVPV Testing Indirect Tensile Testing Flexural Testing Brazil or Splitting Test Modulus of Rupture ni yD yy E Wy N amp N amp N amp Yj f Yj Yi amp Q SG Q SS a amp amp amp N N N amp Q SG SSS Q Z f Q S dl r aan E i amp amp amp N N N RSS SS a SS SS SS y tk amp amp amp Vie Vie Vie i pl z m za F Gea ha au 7 pi E Em a za N ha F S za F N Q i amp 4x 4x 60 cm long Probably a broken formwork stake b Source unknown ie 7 Q Cast Iron NE I x 10 x 50 cm long twis
10. nctions Regular maintenance and panprahon of Spurpoent reduces the girder ee Si systems gt Equipment maintenance Calibration Records Ps Pm Ye yy SSE a nm ie a ie Placeability and Pu j Sr Q CES SSS 8 j Sr CES SSS 8 Q Q N N JIN T za 1 i x CES SSS NN x CES SSS x CES SSS a bilit Q Q NG CES SN X NG Ss Ss 1 SS lt X _ Q a Q a Q il NG SIN SSS _ ie SS ASS SSS 8 ES SSS a a a a PR r Hii a 1 i r a PR amp N ba a mm F N N Fa N ba a mm F N N Fa Ww N ba a mm r N N SE eabi A E A i j a Placability and pumpability is generall following yy a MN SE lt lt Q SS Placabilit a _ a KE S S n Consistency a ZA tk S ye and MS thee is Increase in slump consistency _ SS lt Fi or slump A i i j amp YA Volume of fines a N texture Ol _ and pumpability 1s general N Q _ Increase in paste volume a A 3 a k Bj V S lt
11. ted and corrode piece of iron NG Source unknown i Q 0 5 x 14 x 27 cm Heavy wear on one end CE Source unknown ie Clay Lump Q i NE Approximately 16 cm diameter Contamination is most likely from the Sand Quarry Pit fl Rock Spall NE Approximately 10 cm diameter Hornfels rock Contamination most likely occurred at the Quarry ie SELIP ug i MS sik AA Bin Sisemi fitted grates to reduce the possibility of at i gt contaminants vis 5 8 the production p process faye ft E Ground bins allow init le specialist aggregate products to be stored without contamination Concrete Plant Bins u The Grates prevent WEB falling inside the bin e as well as exposing and rt BU reventing large contaminants from entering the bin YA Batching Tolerances Meeting batching tolerances are a prime concern for every concrete plant AS1379 recognises that tolerance are a practical necessity and has set requirements for all concrete ingredients Errors in batching can alter the concrete s expected properties Some examples are Under batched cement may result in strength loss Over or under dosed admixture may result in setting time variability Over batched coarse aggregate may result in reduced pumpability etc Computers control batching and ensure gt tolerances are met _ of plant malfu
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