TB-1703 — CONCERA® CP1124 Technical Bulletin

Rheology Modifying Water Reducer

/ concrete / mix design


CONCERA® CP1124 is a patent pending rheology modifying polycarboxylate based ASTM C494 Type A water reducer that enables the production of Control Flow Concrete, a highly flowable concrete with minimal or no segregation using unmodified conventional mix designs. Control Flow Concretes typically have slump flow values in the 16-25" (406 to 635 mm) range and may require minimal external energy to properly consolidate. CONCERA® CP1124 is a component of GCP’s Control Flow Concrete System and is typically used in mix designs that also contain a PC based mid or high range water reducer. CONCERA® CP1124 imparts many desirable properties to Control Flow Concrete including segregation resistance, stability, improved passing and filling ability, excellent tolerance to moisture variation and extended slump life. CONCERA® CP1124 also produces concrete with consistent, predictable slump flow and air control properties and readily enables jobsite concrete to be retempered with water to restore slump lost during transit. CONCERA® CP1124 has minimal impact on other concrete properties including early and later age compressive strength and drying shrinkage, while initial time of set and total bleed may slightly increase.

ASTM C 1611-Standard Test Method for Slump Flow of Self-Consolidating Concrete (SCC) details a qualitative visual test procedure for measuring rheology, stability and segregation resistance properties of highly flowable concrete and SCC. The test procedure includes a visual inspection of the concrete spread after the slump flow test is completed. This inspection includes observing the distribution of coarse aggregate within the concrete spread and mortar fraction and bleeding characteristics around the perimeter of the spread. Finally, a Visual Stability Index (VSI) value is assigned to the concrete spread using 0-3 criteria as detailed to the right.

Visual Stability Index Values

  • 0 = HIGHLY STABLE - No evidence of segregation or bleeding.
  • 1 = STABLE - No evidence of segregation and slight bleeding observed as a sheen on the concrete mass.
  • 2 = UNSTABLE - A slight mortar halo ≤ 0.5 in. (≤ 10 mm) and/or aggregate pile in the center of the concrete mass.
  • 3 = HIGHLY UNSTABLE - Clearly segregating by evidence of a large mortar halo ≥ 0.5 in. (≥ 10 mm) and/or a large aggregate pile in the center of the concrete mass.

A CONCERA® CP1124 field test evaluation program using an array of 3500-6500 psi (24.2-44.8 Mpa) mix designs containing different types and quantities of cements, pozzolans and fine and coarse aggregates was conducted at several test sites in North America. The mix design and admixture test matrix included:

  • Conventional 8" (203 mm) slump using polycarboxylate based HRWR
  • Highly flowable 16-25" (406 to 635 mm) slump flow using polycarboxylate based HRWR
  • Control Flow Concrete 16-25" (406 to 635 mm) slump flow using CONCERA® CP1124 rheology modifying water reducer and polycarboxylate based HRWR

TABLE 1 - CONCERA CP1124 Field Test Results

(Results below represent averages from 6 tests)

  Units Conventional HRWR
8” (203mm)
slump mix design
Conventional HRWR
highly flowable
16-25” (406-635mm)
mix design
+PC based HRWR highly flowable 16-25”
mix design
Conventional HRWR dosage rate oz/cwt (mL/100kg) 5 (326) 8.7 (567) 5 (326)
CONCERA CP1124 dosage rate oz/cwt (mL/100kg) - - 10 (652)
Initial slump/slump flow inches (mm) slump-8.1 (206) 23.5 (597) 22.1 (561)
Initial VSI (ranked 0-3) 0-3 (not applicable) 1.7 0.75
Initial VSI description - - unstable stable
60 minute slump flow inches (mm) (not tested) 14.8 (376) 18.5 (470)
60 minute VSI (ranked 0-3) 0-3 (not applicable) 0.45 0.35
60 minute VSI description - - highly stable highly stable
Initial plastic air % 1.8 0.9 1.1
Initial time of set (hr:min) 5:28 6:30 6:20
2/3 day comprehensive strength psi (Mpa) 3287 (22.7) 3428 (23.6) 3324 (22.9)
7 day compressive strength psi (Mpa) 4475 (30.9) 4592 (31.7) 4597 (31.7)
28 day compressive strength psi (Mpa) 5436 (37.5) 5410 (37.3) 5430 (37.4)


Table 1 above details summary of test results including initial slump flow, VSI, plastic air, initial time of set, early, 7, 28 day compressive strength along with 60 minute slump flow and VSI. Field test results clearly show CONCERA® CP1124 produces highly flowable, stable, segregation resistant concrete with excellent slump retention properties over 60 minutes and minimal impact on other pertinent plastic and hardened concrete properties.

Figure 1 below further details polycarboxylate based HRWR (black) and CONCERA® CP1124 (red) concretes VSI values over a range of slump flows. CONCERA® CP1124 concretes also typically contain a PC based MRWR or HRWR. CONCERA® CP1124 concretes consistently show better (lower) VSI values when compared to highly flowable PC based HRWR concrete with all VSI‘s < 1. Note: ACI 237-Self Consolidating Concrete document states – A VSI rating <1 is an indication that the highly flowable concrete is stable. ACI 237 further states that VSI ratings are subjective and should be used primarily as a quality control tool, rather than as a acceptance/rejection criteria for a specific mix design.


When CONCERA® CP1124 is incorporated into a conventional "off the shelf" mix design, and additional incremental improvements to the overall rheology, segregation resistance, stability or other properties are desired, relatively minor and inexpensive mix design modifications can be made. First, most conventional MRWR/HRWR mix designs are designed in the 5-8" (127- 203 mm) slump range and CONCERA® CP1124 has built-in water reducer capability to increase 5+ inch (127 mm) slump concretes up to the highly flowable 16-25" (406 to 635 mm) range. Therefore, since most CONCERA® CP1124 mix designs already contain a PC based MRWR or HRWR, rheology improvements can be realized by slightly reducing the PC based MRWR/HRWR dosage rate and increasing the CONCERA® CP1124 dosage rate. This adjustment will increase the total amount of rheology modifier in the concrete. Several other mix design adjustments are detailed below, with implications related to making a specific adjustment detailed in parentheses. It is highly recommended CONCERA® CP1124 Control Flow Concrete be tested prior to job startup using applicable mix designs and materials.

  • Adjust MRWR/HRWR – CONCERA® CP1124 ratio
  • Reduce total coarse aggregate content (increases drying shrinkage)
  • Reduce nominal coarse aggregate size (increases drying shrinkage)
  • Optimize coarse aggregate particle shape/angularity
  • Optimize coarse aggregate gradation, avoid severely gap graded coarse aggregate
  • Increase fine agg, reduce coarse agg content (water demand and shrinkage impact)
  • Increase mortar and/or paste fraction (water demand and shrinkage impact)
  • Slightly increase total cementitious content
  • Incorporate or increase the percentage of fly ash in the mix design
  • Reduce slump flow to low end of 16-25" (406 to 635 mm) range (workability impact)
  • Slightly increase plastic air content (strength impact)
  • Slightly reduce water content, increase CONCERA® CP1124 dosage rate

In summary, a widespread North America based field test program confirmed CONCERA® CP1124 enables the production of 16-25" (406 to 635 mm) Control Flow Concrete with minimal or no segregation using typically unmodified conventional mix designs. CONCERA® CP1124 imparts many other desirable properties to Control Flow Concrete including improved passing and filling ability, tolerance to moisture variation, consistent slump flow and slump flow retention properties and minimal impact on compressive strength and set time. Several minor mix design modifications can also be tested and implemented if additional improvements to overall rheology, stability and segregation resistance properties are desired

gcpat.com | North America Customer Service: 1 877-4AD-MIX1 (1 877-423-6491)

We hope the information here will be helpful. It is based on data and knowledge considered to be true and accurate and is offered for consideration, investigation and verification by the user, but we do not warrant the results to be obtained. Please read all statements, recommendations and suggestions in conjunction with our conditions of sale, which apply to all goods supplied by us. No statement, recommendation, or suggestion is intended for any use that would infringe any patent, copyright, or other third party right.

CONCERA is a trademark, which may be registered in the United States and/or other countries, of GCP Applied Technologies Inc. This trademark list has been compiled using available published information as of the publication date and may not accurately reflect current trademark ownership or status.

© Copyright 2018 GCP Applied Technologies Inc. All rights reserved.

GCP Applied Technologies Inc., 62 Whittemore Avenue, Cambridge, MA 02140 USA.

In Canada, 294 Clements Road, West, Ajax, Ontario, Canada L1S 3C6.

This document is only current as of the last updated date stated below and is valid only for use in the United States. It is important that you always refer to the currently available information at the URL below to provide the most current product information at the time of use. Additional literature such as Contractor Manuals, Technical Bulletins, Detail Drawings and detailing recommendations and other relevant documents are also available on www.gcpat.com. Information found on other websites must not be relied upon, as they may not be up-to-date or applicable to the conditions in your location and we do not accept any responsibility for their content. If there are any conflicts or if you need more information, please contact GCP Customer Service.

Last Updated: 2021-02-05