Multi-crystalline Intermixed Concrete Enhancer for Improving Concrete Durability and Performance
Chem-Crete’s MCETM, an intermixed multi-crystalline enhancer, is a significant step forward in increasing long-term Portland Cement Concrete (PCC) performance and durability. MCETM is an aqueous solution that is mixed into fresh PCC during the batching process resulting in uniform distribution throughout the Portland cement paste. The material has been shown through extensive laboratory studies and field trials to enhance the hydration of the Portland cement, increase workability, improve strength, reduce capillary porosity, reduce chloride intrusion and numerous other benefits as highlighted in the PRODUCT FEATURES section.
A key feature of MCETM is its ability to actively manage water in the PCC thereby minimizing or eliminating moisture-related damage including freeze/thaw cycling and alkali silica reactivity (ASR). In addition, by controlling the amount of water entering the concrete, chloride intrusion is minimized, mold growth is inhibited, and overall PCC sustainability greatly enhanced.
MCETM is applicable to both central mixed and ready mixed plant operations. The method of incorporating the material into the PCC during the batching process is somewhat dependent on the specific batching equipment. However, the MCETM is generally added into the water feed similar to chemical admixtures.
The research results presented below illustrate key findings and is not intended to be all inclusive. In-depth research results are available on request.
Alkali-Silica Reactivity (ASR): the following tests results were based on ASTM C-1567, “Determining the Potential Alkali-Silica Reactivity of Combinations of Cementitious Materials and Aggregate (Accelerated Mortar Bar Method)”. The Platte river aggregates used in the test have been characterized as highly reactive.
The addition of 2% of MCE™ by weight of cement reduced expansion from 32% for the 0.47 w/c ratio to 74% for the 0.39 w/c ratio. This significant level of reduction in ASR is due to improved hydration, alteration of the hydration products (CH versus C-S-H) and enhanced moisture control.
Figure 1: Increasing resistance to the alkali-silica reactions with MCE™. According to ASTM C 1567, using IDOT C4 PCC mix.
Freeze-Thaw Resistance: the following test results were based on a modified and more stringent ASTM C-666, “Standard Test Method for Resistance of Concrete to Rapid Freezing and Thawing”.
The mass change for the control sample shows a mass loss of approximately 5.5% after 300 freeze thaw cycles. The equivalent data for the 2 percent intermixed MCE™ shows a mass loss of only 0.5%. A reduction of approximately 90% in mass loss indicates that the concrete is highly freeze/thaw resistant and therefore will have greatly enhanced durability.
The dynamic modulus of the baseline and 2% intermixed samples was also evaluated according to ASTM C-666. The results showed an increase of approximately 20% for the intermixed samples thereby showing the dramatic improvement in engineering properties of the PCC.
Figure 2: Increasing resistance to freeze thaw cycles with MCE™ at 2% of cement weight. According to ASTM C 666, using IDOT C4 PCC mix.
Figures 3.a and 3.b below show the results of the mass change for the baseline untreated specimens and the intermixed 2% MCE™ respectively. These results show a 91.6% reduction in mass loss for the treated specimens compared with the control.
Figure 3.a: Mass Change of Untreated Mix
Figures 4.a and 4.b show the relative dynamic modulus change in the untreated and treated specimens respectively. The 2% intermixed MCE™ resulted in a 20.3% higher retained dynamic modulus.
Figures 5.a and 5.b show the length change for the untreated and treated specimens respectively. The treated specimens show a 14.8% reduction in length change compared with the untreated specimens at 300 F/T cycles.
Figure 5.a: Length Change – Untreated Mix
Figure 5.b: Length Change – Treated Mix 2%
Compressive Strength: the average compressive strength at all ages evaluated is enhanced by the addition of the intermixed MCE™. Most noteworthy is the average 28-day compressive strength, the curing period typically specified for highway paving, is 5.8% higher. The implications are that a pavement design thickness based on a non-MCE™ enhanced PCC could be slightly thinner for the same load carrying capacity.
Figure 6: Enhanced compressive strength of MCE™.
Resistance to Chloride Ion Penetration: the chloride permeability of the intermixed MCE™ was evaluated according to a slightly modified ASTM C-1202, Standard Test Method for Electrical Indication of Concrete’s Ability to Resist Chloride Ion Penetration procedure. The 2% intermixed sample showed a reduction of 90.7 percent compared with the baseline value. In practical terms, this implies that the concrete is less permeable, has a higher density and is more resistant to intrusion by chloride ions from deicing salts.
Workability: the effective crystallization mechanism of MCE™ enhances slump as indicated in figure 7, with results are for the case of concrete mix with a slump target of 1 in, obtained by an independent laboratory testing according to ASTM.
Figure 7: Enhanced workability of MCE™
Figure 8 below shows slump and workability (retention) data for concrete mix designs with and without fly ash.
Figure 8: Concrete Workability (retention) Data for PAVIX MCE™
Thermal Properties: based on observations during the Freeze/Thaw (F/T) and related testing, the 2% intermixed MCE™ was shown to delay the freezing of the concrete test specimens. Although there are no current ASTM specifications that are applicable, a procedure was developed to evaluate the observed behavior.
The untreated PCC specimen reached freezing temperatures at approximately 3 days at the surface and 3 to 4 days at the center of the specimen when subjected to temperatures of minus 64o F. The addition of 2% MCE™ showed that the interior of the PCC specimen never reached freezing temperature while the surface took approximately 14 days. The implications of this are very significant in that the effect of surface temperature of the concrete has a direct impact on the formation of ice on the pavement surface as well as the application of deicing chemicals.
MCE™ has a distinguished thermal behavior of preventing water freezing in treated concrete under severe continuous freezing conditions. Figure 9 below shows the high performance of remaining MCE™ modified concrete above freezing temperature for about 2 months even under severe continuous (when the concrete is continuously subjected to -50oF), while the temperate of the control sample dropped to a value below freezing within three days.
Figure 9: Concrete thermal performance under continuous freezing surroundings, reporting the temperatures at two positions: top (0.5 inch below surface) and middle (1.5 inch below surface) for a concrete with a mix design of IDOT C4, comparing control sample with concrete mixed with 2% MCE™. The tests were made in freezing chambers used for ASTM C-666, with the temperature of the chamber adjusted to -50oF and remained constant to create more severe freezing conditions.
Method of Application: MCETM is shipped in a ready-to-use state, with no additional preparation prior to use. The product is simply mixed with the concrete at the time of batching and is applicable to both ready-mixed and central mix production.
Blending: The MCETM should be introduced into the water stream at the time of batching.
Consumption: 2% by weight of cement
Cleaning: clean all equipment, tools with fresh clean water immediately after use.
Two years shelf life when stored in cool, dry place in its original unopened container. Always agitate or stir the product’s container before using. DO NOT ALLOW PRODUCT TO FREEZE. Repeated freezing & thawing might cause damage for the product.
As with all construction chemical products, adequate precautions and care must be taken during usage and storage. Avoid direct contact with foodstuff, eyes, skin, and mouth. Any direct contact with skin, eyes, etc. should be washed thoroughly with clean running water and soap.
Always wear protective goggles and gloves. In case of eye contact, flush for 15 minutes with warm water. KEEP OUT OF REACH OF CHILDREN.
LIMITED WARRANTY: International Chem-Crete Inc. warrants that, at the time and place we make shipment, our materials will be of good quality and will conform to our published specifications in force on the date of acceptance of the order.
DISCLAIMER: The information contained herein is included for illustrative purposes only and, to the best of our knowledge, is accurate and reliable. International Chem-Crete Inc. is not under any circumstances liable to connection with the use of information. As International Chem-Crete Inc. has no control over the use to which others may put its products, it is recommended that the products be tested to determine the suitability for specific applications and/or our information is valid in particular circumstances. Responsibility remains with the architect or engineer, contractor and owner of the design, application, and proper installation of each product. Specifier and user shall determine the suitability of the product for specific application and assume all responsibility in connection therewith. MA101019.