Accelerated Strength Testing of Portland-Pozzolan Cement Concretes by the Warm Water Method


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Title: Accelerated Strength Testing of Portland-Pozzolan Cement Concretes by the Warm Water Method

Author(s): Erbil Oztekin

Publication: Materials Journal

Volume: 84

Issue: 1

Appears on pages(s): 51-54

Keywords: accelerated tests; cement content; compressive strength; concretes; cylinders; portland-pozzolan cements; quality control; regression analysis; research; water-cement ratio; Materials Research

Date: 1/1/1987

This study investigated the accelerated test results of portland-pozzolan cement concretes by the warm water method. The portland-pozzoloan cement used contains 30 percent natural pozzolan. The laboratory work involved the production of concrete mixes with cement contents of 300 to 450 kg/m3, water-cement ratios varying between 0.3 and 0.63. Both gravel and crushed aggregates were used. Compressive strengths were measured on 150 x 300 mm cylinder specimens at 1 and 28 days. Analysis of the results revealed that the within-batch coefficient of variation was 3.9 percent for both accelerated and 28-day strengths. The relationship between 28-day and accelerated strengths can be expressed by either a linear or a power-type equation. Using the linear relationship, 28-day strength can be estimated with 2.8 MPa accuracy within 95 percent confidence limits. The relationship is compared to and found to be in agreement with those proposed by other investigators for different cements. However, accelerated strengths given by the portland-pozzolan cement seem to be a little higher than those given by Type I or II cements.