Problem Clinic

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    Quality's Costs

    Q: I'm a quality control manager for a mid-size ready-mix producer and am dealing with several quality issues which need resolution. I am having difficulties convincing the owner that he needs to increase funding for the quality system in order to produce more consistent concrete. How can I...

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    Working With Your Lab

    Q: We are experiencing low compressive strength test results on some concrete we supplied to a job. We know it is due to poor testing of the cylinders. How do we convince the contractor and engineer where the issue is?

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    Testing for Air in Concrete

    We retrieved a piece of the material and an air-void analysis showed that the air content met the project spec. What happened?

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    Is Your Aggregate Alkali-Silica Reactive?

    Q: We received a request to submit proof that our aggregates are not alkali-silica reactive. We've never seen this type of request before in our area. They required ASTM C1260 testing, which we completed and failed. What do we do now?

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    Tread Lightly When Going Green

    Q: We operate in an area that does not have many LEED projects. However, we are now seeing more such projects under development, and specifications requiring LEED submittals are becoming more frequent. How can we manufacture concrete to meet these requirements, and how can we make our concrete more...

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    Making a Quality Hire

    Q: We are a small but growing ready-mix producer. We have just decided to open a portable plant to service a multiyear project. We are considering hiring a full-time quality control manager. At what annual production volume does it make sense to make this hire?

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    Lightweight Block As An Alternative

    Q: We are working on a project where the owner is trying to earn LEED credits. So we are trying to convince the structural engineer to use lightweight block. How can we get him to use lightweight block as an alternative?

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    Do Fibers Affect Concrete's Workability?

    Q: We will be supplying ready mixed concrete for a commercial floor project. The engineer of record has added fibers to the project specification. The concrete contractor is now concerned that with this job change, the fibers may slow his placement procedures and has submitted a change order...

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    Wall Ties and Wind Load

    Q: If the purpose of these ties is to support the veneer during winds, why does it make any difference what backup is used?

  • Working With Controlled Low-Strength Materials

    We are about to bid on a project calling for controlled low-strength materials (CLSM) for backfilling sewers and other underground utilities. The designer is hoping to use this material to earn LEED credits. We have been asked to verify the density of CLSM we plan to provide. Does CLSM's density...

  • Can a Contractor Add Fibers?

    QUESTION: We recently worked with a new customer, and the concrete contractor's owner arrived on the jobsite just as the pour was about to start. He unloaded several boxes containing pre-weighed packages of synthetic fibers.

  • Problem Clinic

  • How Long Can a Ready-mix Truck Wait?

    We were all set to start when the testing lab's field tech stopped the pour. He said the concrete was too old and he had no option but to reject all of the loads. Was the testing lab's field rep correct in rejecting the loads? Was there an alternative?

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    Sampling Small Stockpiles

    Q: In a move to keep our costs low, we have been reducing stockpile inventory. Now for small special jobs, we have literally had only one or two truck dumps of coarse aggregate in our plant for the pour. What is the best method to sample for gradation on stockpiles made by single truck dumps?

  • Predicting Service Life of Concrete

    Q: We've been asked by a design-build firm to submit a mix design on an upcoming project that may be considered for LEED accreditation.

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    To Paint or Not to Paint?

    Q: I never understand why people paint brick masonry. When brick masonry is painted, it must be maintained more frequently to replace areas of paint that have chipped, peeled, or are otherwise defaced.

  • An Ounce of Prevention

    Q: I have seen projects where every third brick along the base of the wall is left out of the wall.

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    Keeping Condo Conversions Dry

    Q: We are converting a masonry office building into condominiums. The building is constructed with solid masonry walls that are three and four wythes thick.

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    Bidding an RCC Paving Project

  • Grout Admixtures

    Q: Should grout contain any special admixtures when it is used in concrete masonry made with integral water repellent?


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