1. Are there any limitations that affect the performance of Xypex Admix?
Use of Xypex Admix requires a minimum of 10% Portland cement content. Of course, optimum effectiveness will be dependent on a number of factors such as thickness of the concrete, Portland cement content, whether there is sufficient reinforcing steel for strength and crack control, quality of placing and finishing practices, sealing of construction joints etc. Typically, Xypex requires a minimum concrete thickness of 5 cm (2”) and a minimum design strength of 20 MPa (3,000 psi).
2. Can Xypex Admix be used in concrete containing fly ash, micro-silica or slag cement?
Yes. Xypex Admix is very effective when used in modern mix designs that incorporate cementitious replacement materials i.e. fly ash, silica fume and blast furnace slag. The reactions that take place to form the crystalline structure are very complex. During the cement hydration process, Xypex’s active chemicals not only react with calcium hydroxide and unhydrated cement particles but also with various metal oxides and mineral salts, regardless of the cement type used. Consult with a Xypex Technical Services Representative to determine dosage rates for such blended cement mix designs.
3. Can Xypex Admix be used in concrete containing other additives such as a water-reducer, plasticizer or air-entrainment agent?
Yes. Xypex Admix has been used successfully in concrete mix designs containing a variety of other admixtures. However, it should be noted that the use of retarding admixtures at recommended dosage rates may cause further extension of set time when used with Xypex Admix. Consult with a Xypex Technical Services Representative for assistance in determining which version of Xypex Admix to use and the appropriate dosage rate.
4. How are the set time and compressive strength of concrete affected by the addition of Xypex Admix?
The set time of concrete is affected by the chemical and physical composition of ingredients, temperature of the concrete and climatic conditions. Extension of set time may occur when using Xypex Admix. The amount of extended set will depend upon the concrete mix design and the dosage rate of the Admix. Concrete containing Xypex Admix may develop higher ultimate strengths than untreated concrete. Trial mixes should be carried out under project conditions to determine set time and strength of the concrete.
5. Is Xypex Admix available in soluble bags?
Yes. In North America, Australia, S.E. Asia, Europe, the Middle East and Africa, Xypex Admix is now available in soluble bags. Xypex Admix C-500/C-500 NF and C-1000/C-1000 NF are available in a variety of conveniently sized soluble bags to meet specific batching requirements. They enhance quality control and eliminate dust during dosing.
6. What is the difference between the various additives in Xypex’s Admix C-Series?
All variations of the Admix C-Series contain the same amount of reactive chemicals at their prescribed dosage rates and provide the same waterproofing and durability performance characteristics. Xypex Admix C-Series is available in regular or no-fines grades (NF). Xypex Admix C-500/C-500 NF is formulated to have minimal or no effect on setting time. Xypex Admix C-1000/C-1000 NF is formulated for concrete mix designs where a normal or mildly delayed set is desired. Xypex Admix C-2000/C-2000 NF is designed for warmer climates and projects where a slower hydration rate is typically required.
7. What is the recommended dosage rate for Xypex Admix?
Xypex Admix is added to the concrete mix at a dosage rate within the range of 2 – 3% by weight of the cement content. Where the “No Fines” (NF) grade is utilized, the equivalent dosage rate is 1 – 1.5%. For assistance in determining the appropriate dosage rate for a particular project, consult Xypex technical literature or contact a Xypex Technical Services Representative.
8. When is Xypex Admix introduced into the concrete mix?
Xypex Admix is added to the concrete mix at time of batching. The sequence for the addition of the Admix powder will vary depending on the type of batching operation and equipment, e.g. ready-mix plant (dry batch operation), ready-mix plant (central mix operation), or precast batch plant.