Use of Dynamic Cone Penetration and Clegg Hammer Tests for Quality Control of Roadway Compaction and Construction

Abstract

Soil compaction quality control presently relies on the determination of the in-place compacted dry unit weight, which is then compared with the maximum dry unit weight obtained from a laboratory compaction test. INDOT requires that the in-place dry unit weight for compacted soil be over 95% of the laboratory maximum dry unit weight. In order to determine the in-place dry unit weight, INDOT engineers generally use nuclear gauges, which are hazardous and also costly because of the required safety precautions. Thus, several alternative tests such as the Dynamic Cone Penetration Test (DCPT) and the Clegg Hammer Test (CHT) were introduced as testing tools for soil compaction quality control. However, no reliable correlations are available in the literature to employ these tests for soil compaction quality control. The main objectives of this research were to evaluate the use of the DCPT and the CHT results to develop criteria for soil compaction quality control. A number of DCPTs and CHTs was performed on Indiana road sites, in a test pit, and in the soil test chamber at Purdue University. Since soil compaction varies from place to place, a statistical approach was applied to account for the compaction variability in the development of the criteria for soil compaction quality control. Based on the DCP tests performed on several INDOT road sites, as well as in the test pit at Purdue University, and the requirement that the in-place dry unit weight of the fill material be over 95% of the laboratory maximum dry unit weight, minimum required DCP blow counts (NDCP)req were proposed for soils belonging to three groups of the AASHTO (American Association of State Highway and Transportation Officials) soil classification system. For the DCPT, the minimum required blow count for 0-to-12 inch penetration, (NDCP)|0~12" associated with an RC of 95% for A-3 soil varied from 7 to 10; it is a function of the coefficient of uniformity. For A-1 soil and A-2 soils except those containing gravel, the (NDCP)|0~12" was a function of the optimum moisture content. For silty clays, the minimum required blow counts, (NDCP)|0~6" and (NDCP)|6~12" were a function of the plasticity index and the soil percentage passing the #40 sieve. Since the relationship of Clegg Impact Value (CIV) with relative compaction exhibited considerable variability, no criterion for CHT was proposed. Dynamic analyses hold promise in forming the basis for interpretation of the DCPT and CHT results since predictions of the penetration process (DCPT) and accelerations (CHT) for sand under controlled conditions were very reasonable.

QA/QC of Subgrade and Embankment Construction: Technology Replacement and Updated Procedures

“…Further work still needs to be carried out in the direction of establishment of the scale of fluctuation of compacted soils to further refine the preliminary large-scale testing procedure proposed in this research. Kim et al (2010) 8 Table 2.6 Correlations developed by White et al (2002) 9 Table 4.1 Field testing locations, dates and number of tests performed 13 Table 4.2 Soil grouping criteria 14 Table 4.3 Location codes 14 Table 4.4 Combined test results for fine-grained soils 14 Table 4.5 Combined test results for coarse-grained soils 15 Table 5.1 Field test results for fine-grained soils 18 Table 5.2 Field test results for coarse-grained soils 19 Table 6.1 Index properties of soils tested by Kim et al (2014) 25 Table 6.2 Index properties of soils from the literature 25 Table 6.3 Soil grouping 27 Table 6.4 Tabular form of recommended blow count values for manufactured coarse-grained soils (INDOT jargon5 granular) commonly used by INDOT in earthwork projects 30 Table 6.5 Index properties and corresponding blow counts for 0 to 6 inches of penetration for the soil used in the moisture sensitivity tests performed by INDOT 31 Table 6.6 DCPT correlations 32 Table 6.7 Implementation plan for DCP correlations 32 Table 7.1 Soil group properties 33 Table 7.2 Comparison of parameters of Beta and Normal distributions 37 Table 7.3 Distribution fitting parameters for the field grid testing 39 Table 7.4 Simulation results-percentile and corresponding variances 39 Table 7.5 DCP test results from variability study 41…”

“…The data collected strongly indicated that reasonable correlations could be developed between the DCPT blow count required to satisfy INDOTs relative compaction criteria and the controlling soil properties that affect the mechanical response of the soil to the loading by the DCP (Kim et al, 2010). The most important aspects that needed further research were: (1) identification of the main soil groups that showed similar response to the impact loading from the DCP, (2) identification of an individual or a combination of controlling properties that govern the mechanical response of each soil group to loads applied by the DCP, and (3) quantification of the effect of the moisture content of the subgrade soil after compaction on the DCP blow count measured.…”

“…Although the criteria previously established by Kim et al (2010) did remarkable work in addressing many of the issues associated with the establishment of DCPT blow-count criteria for compacted subgrade, further research was still needed on the three aspects outlined above. Collection of a wide-ranging set of field and laboratory test data was required to augment the data set collected in previous studies and in the development of a more reliable DCP-based quality control criteria.…”

“…As many other DOTs before it, when INDOT decided that a move towards use of the dynamic cone penetration test (DCPT) for compaction quality control was potentially in its interest, it funded preliminary projects (Kim et al 2010;Luo, Salgado, & Altschaeffl, 1998;Salgado & Yoon, 2003) to assess the viability of using the DCPT for this purpose and to develop a methodology to do so reliably. Data was collected and organized from field and laboratory test results aiming at establishing the basis for the development of proper correlations between DCPT results and end-product specifications, as adopted by INDOT.…”

“…The objective of this research was to develop QA/QC correlations for the DCP that will be applicable for all types of soils found in Indiana and to address some of the issues associated with soil grouping and moisture sensitivity in previously developed correlations by Kim, Prezzi, and Salgado (2010). As many other DOTs before it, when INDOT decided that a move towards use of the dynamic cone penetration test (DCPT) for compaction quality control was potentially in its interest, it funded preliminary projects (Kim et al 2010;Luo, Salgado, & Altschaeffl, 1998;Salgado & Yoon, 2003) to assess the viability of using the DCPT for this purpose and to develop a methodology to do so reliably.…”