FREQUENTLY ASKED QUESTIONS
Type K cement is a blended cement consisting of KomponentΠcementitious shrinkage-compensating additive and portland cement. It is commonly blended at time of batching at the central batch plant with regional Type I, II, IV or V portland cement. Or it can be pre-blended at the manufacturing facility with Type II portland cement.
Yes. ACI 223 - Guide for the Use of Shrinkage-Compensating Concrete and various ASTM standards (i.e., ASTM C845, ASTM C806 and ASTM C878) are available to guide engineers, design professionals, construction teams, and testing labs in the design, specification, performance and installation of Type K shrinkage-compensating cement concrete and non-shrink grout.
Shrinkage-compensating concrete is engineered to fully compensate for the drying shrinkage characteristics of portland cement, aggregates, and other supplementary cementitious materials used in a concrete mix design. Komponent is a cementitious additive that improves the cement paste and provides shrinkage-compensation for the life of the placement. Its affects do not diminish over time.
Shrinkage-compensating concrete can be used for any concrete element or grouting project. From industrial, commercial, and institutional construction projects to mass elements, bridge decks, parking lots, pavement, sea walls and underground or submerged applications. Anywhere you can use portland cement concrete you can use Type K shrinkage-compensating cement concrete.
Shrinkage-compensating concrete cannot overcome poor design or installation practices. As with all concreting projects, best practices must be used in structural designs, mix designs, installation practices, and curing methods.
Shrinkage-compensating concrete offers the most flexibility in design and joint spacing. With L:W ratios up to 3:1, joint spacing of long narrow spans like bridge decks can be extended up to 300 ft or more. Floor slabs are commonly spaced up to 150 feet with no control joints.
Minimum reinforcement requirements are provided in ACI 223 - Guide for the Use of Shrinkage-Compensating Concrete, Section 5.2.2. "A minimum ratio of reinforcement area to gross concrete area of 0.0015 is desired." Minimum reinforcement is required to control expansion and maximize performance of the tensile and compressive stress in the concrete. No maximum reinforcement is defined. The amount of reinforcement has an inverse relationship to the expansion that can be achieved, with compressive stresses increasing as the amount of reinforcement increases.
Komponent offers every design and construction team the most reliable method of minimizing or eliminating drying shrinkage cracking and unsurpassed dimensional stability (eliminating curling, minimizing creep and moment, etc.). It cannot, however, overcome poor installation practices, insufficient structural design, or inadequate mix designs. ASTM C878 should be run on all mix designs to ensure dosages will meet performance requirements.
Type K shrinkage-compensating cement concrete typically exhibits a 10-15% improvement in both compressive and flexural strengths, depending on the mix design used.
The advanced hydration mechanism of a Type K cement is different than that used by portland cement. This more efficient chemical reaction consumes mix water to create ettringite crystals. These crystals improve the quality of the cement paste and create expansion in the concrete. Water is needed for the chemical reaction that takes place during hydration so it is important not to starve Komponent of the water needed to achieve the designed expansion.
Air entrainment additives react the same in shrinkage-compensating concrete as they do in portland cement concrete and can be used successfully in regions that require air entrainment.
The advanced hydration mechanism of a Type K cement is different than that used by portland cement. This more efficient chemical reaction consumes mix water to create ettringite crystals. There is no "excess" mix water to find its way up and out of the concrete, effectively creating a more dense, less permeable concrete.
Type K cement is available nationwide and internationally. It is sold direct to market. Interested customers simply need to contact our corporate office or a member of our Engineering Sales Team and we can help facilitate the order.
Pre-blended Type K cement is available in bulk rail or tanker trucks, 2000-lb super sacks, and 94-lb bags. If blended at the batch plant, Komponent is available in bulk rail or tanker trucks, 2000-lb super sacks, 90-lb bags and 50-lb bags.
Bulk pre-blended Type K cement should be stored in a sealed bulk storage container like a silo or rail car and protected from adverse environmental conditions and moisture. Bags of Komponent must be stored in a dry location, protected from moisture, out of direct sunlight, and protected from damage to packaging.
Traditional means, methods and best practices for concreting are used with shrinkage-compensating concrete. However, it is not "just like portland". As with any additive or SCM used in a concrete mix design, understanding how Komponent affects the mix is important for the producer, and the placing and finishing teams. Understanding the most effective means of adjusting set time and slump is important. And ensuring installation teams understand they should not wait for bleed water before finishing, and the timing of wet cure need to be understood prior to the pour. A pre-pour meeting goes a long way to ensuring efficiency during production and placement, as well as successful finishing and curing processes.
Water is only added at the plant during the batching process. If slump adjustments are needed on site, plasticizers should be used.
No. The expansion created by shrinkage-compensating concrete is restrained by the reinforcement in the concrete (traditional rebar, microfibers, or micro-rebar). Estimates of maximum member expansion relative to the amount of reinforcement used in the concrete element can be evaluated in ACI 223 Fig. 5.1.