Details:

Creators:
Yohannes, Yohannes ; Olek, Jan
Yohannes, Yohannes ; Olek, Jan Less -
Corporate Creators:
Purdue University. Joint Transportation Research Program
Corporate Contributors:
United States. Federal Highway Administration
Subject/TRT Terms:
[+]
Concrete--Moisture--Measurement Concrete Mixing Evaluation And Assessment Field Tests Laboratory Tests Pavements, Concrete--Testing Water Cement Ratio Weight
Publication/ Report Number:
FHWA/IN/JTRP-2012/24
Resource Type:
Tech Report
Geographical Coverage:
United States
Edition:
Final report.
Corporate Publisher:
Indiana Department of Transportation
Abstract:
The fresh concrete water‐cement ratio (w/c) determination tool is urgently needed for use in the QC/QA process at the job site. Various

techniques have been used in the past to determine this parameter. However, many of these techniques can be complicated and time

consuming. Furthermore, the extensive calibration is often needed to correlate the properties measured by these techniques with w/c.

During the course of the present study, the method for the use of the unit weight for the determination of w/c of fresh concrete has

been developed and evaluated on both laboratory and field concretes. Additionally, the accuracy of using microwave oven technique

for w/c determination reported by previous research was confirmed. Finally, the accuracies of unit weight and microwave oven

techniques for the determination of w/c were compared.

The unit weights required for this method have been determined either by using a “zero‐air” procedure (ZAP) developed as a part of this

study or by using conventional (following AASHTO specifications) methods. The ZAP technique was used to verify the w/c of 58 different

laboratory concrete mixes. These verification efforts revealed that the minimum, maximum, standard error, and 95th percentile of the

differences (Δw/c) between batched and determined w/c were, respectively, 0.000, 0.042, 0.017, and 0.030. The AASHTO determined

unit weight (which also required measurements of the actual air content of concrete) was used to verify the w/c values of additional set

of 57 laboratory mixes. When using the AASHTO unit weights (and air contents) the minimum, maximum, standard error, and 95th

percentile of Δw/c of were, respectively, 0.000, 0.075, 0.030, and 0.054. In addition, the AASHTO unit weight method was also used to

verify the w/c values of 22 different field mixtures. For this case, the differences (Δw/c) between the design and unit weight‐calculated

values of w/c were in the range ±0.030 for all but one mixture. Finally, direct comparison of the results from the proposed method with

the results obtained from the microwave oven method revealed that the former is faster but slightly less accurate. Specifically, when

used on five separate concrete samples, the accuracy of the microwave oven method was 0.010, much smaller than previously

mentioned values of 0.030 (for the ZAP) and 0.054 (for the AASHTO) unit weight methods.


Format:
PDF
Funding:
SPR-3201
Collection(s):
US Transportation Collection
Main Document Checksum:
[+]
urn:sha256:39fd8274f7b015c2096e1e43070543398aaffaa38ef52b906493cad82ef6afda
Download URL:
https://rosap.ntl.bts.gov/view/dot/25472/dot_25472_DS1.pdf
File Type:

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