Page 14 - FC Spring 2022
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        A Look Inside the

        Concrete Slab

                                                                         BY DAVID SELAND, PRINCIPAL, ISE LOGIK

                here is a classic urban legend—a scary one—where a   to form a cementitious liquid slurry, which can be easily poured,
                young woman is either home alone or babysitting when   placed, and molded. The slurry wraps around the ingredients to
                she gets a creepy phone call. She calls the police. They   form a hard matrix that creates the durable, structural material
        Ttrace it and tell her, “The calls are coming from inside the   known as concrete. To demonstrate how essential water is in the
        house.” It’s shocking and goosebump-inducing every time because   production of concrete, concrete mixes are often described by their
        the bad guy has already breached the perimeter. In architecture,   water-to-cementitious-material ratio or their w/cm. It is calculated
        there’s a similar story and, although fewer movies have been made   by dividing the pounds of water by the pounds of total cementitious
        about it, it’s even more terrifying because it’s true. The villain, in   material. A 0.45 w/cm mix refers to a concrete mix where the weight
        this story, is moisture, and, in most commercial structures, it’s   of water is 45% of the weight of the total cementitious material. To
        already inside. That’s right. Traditional concrete is a trojan horse for   put that in context, a full truckload of concrete mix could easily
        moisture.                                           contain more than 320 gallons of water.
        The Ingredients in Concrete                         Introducing Admixtures
          Concrete is a composite material composed of fine and coarse   Almost all concrete mix designs also contain at least one
        aggregates bonded together with a fluid cement (cement paste) that   chemical or mineral admixture. An admixture is defined as any
        hardens over time. Supplemental cementitious materials such as   material other than water, aggregates and hydraulic cement that
        fly ash, slag, and silica fume are also regularly present, in varying   is used as an ingredient in concrete or mortar and is added to the   Photos courtesy ISE Logik
        amounts, in a concrete mix composition.             batch immediately before or during batching. Batching refers to the
          One of the main ingredients necessary for the creation of   part of the process where the different concrete materials—cement,
        concrete is water. Water is mixed with the cement and aggregate   aggregates, admixture, etc.—are measured and combined.  Once

   14    The Flooring Contractor Magazine     Spring 2022
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