1 Intro 2 Sustainability 3 Design Do not require cements with special properties unless the special properties are necessary. Project specifications should focus on the needs of the concrete pavement and allow the use of a variety of materials to meet those needs. A cement may meet the requirements of more than one type or specification. For instance, a material classified as Type II will also comply with the requirements for Type I, and likewise a material classified as Type V will also comply with the sulfate requirements for Type II. Table 4-4 lists hydraulic cement types for various applications. Hydraulic materials will set and harden when mixed with water. Slag cement is a hydraulic material. Pozzolanic materials require a source of calcium hydroxide (CH), usually supplied by hydrating portland cement. Class F fly ashes are typically pozzolanic, while Class C fly ash has both hydraulic and pozzolanic characteristics. Use of SCMs in concrete mixtures has been growing in North America since the 1970s. There are similarities among many of these materials: • SCM chemical reactions complement or are synergistic with portland cement chemical reactions. Using Unfamiliar Cements 4 Materials • Most SCMs are byproducts of industrial processes. 5 Hydration As with other concrete ingredients, if an unfamiliar portland cement or blended cement is to be used, the concrete should be tested for the properties required in the project specifications (PCA 2000, Detwiler et al. 1996). • The judicious use of SCMs is desirable, not only for the environment and energy conservation, but also for the technical benefits they provide to concrete. 6 Properties SCMs can be used to improve a particular concrete property, such as resistance to alkali-aggregate reactivity. However, mixtures containing SCMs should be tested to determine whether (1) the SCM is indeed improving the property, (2) the addition rate is optimum, and (3) there are not any unintended effects such as a significant delay in early strength gain. It is also important to remember that SCMs may react differently with different cements (see Potential Materials Incompatibilities in Chapter 5). Supplementary Cementitious Materials In at least 60 percent of modern concrete mixtures in the US, portland cement is supplemented or partially replaced by SCMs (PCA 2000). When used in conjunction with portland cement, SCMs contribute to the properties of concrete through hydraulic or pozzolanic activity, or both. 7 Mixtures Table 4-4. Cement types for common applications* Moderate sulfate resistance (in contact with sulfate soils or seawater) High early strength (patching) Low heat of hydration (very massive elements) High sulfate resistance (in contact with high sulfate soils) ASTM C150/ AASHTO M 85 portland cements I II(MH) II, II(MH) III IV V ASTM C595/ AASHTO M 240 blended cements IL IP IS(<70) IT(S<70) IL(MH) IP(MH) IS(<70)(MH) IT(S<70)(MH) IL(MS) IP(MS) IS(<70)(MS) IT(S<70)(MS) — IL(LH) IP(LH) IS(<70)(LH) IT(S<70)(LH) IL(HS) IP(HS) IS(<70)(HS) IT(S<70)(HS) ASTM C1157 hydraulic cements GU MH MS HE LH HS Cement specification 8 Construction 9 QA/QC 10 Troubleshooting General purpose Moderate heat of hydration (massive elements) *Check the local availability of specific cements because all cement types are not available everywhere. Source: Adapted from Kosmatka and Wilson 2016 56 Integrated Materials and Construction Practices for Concrete Pavement