Investigation of Premature Distress Around Joints in PCC Pavements: Parts I & II

Some of the Indiana concrete pavements constructed within the last 10-20 years have shown signs of premature deterioration, especially in the areas adjacent to the longitudinal and transverse joints. This deterioration typically manifested itself as cracking and spalling of concrete combined with the loss of material in the direct vicinity of the joint. In addition, in some cases “bulb-shaped” damage zones were also observed under the sealed parts of the joints. The objective of this study was to investigate possible causes of this premature deterioration. To reach this objective, the characteristics of the concrete in and near the deteriorated joints were compared and contrasted to the concrete characteristics in the non-deteriorated sections of pavement. The study was conducted in two different phases (Phase I and Phase II), and the findings are presented as a two-part report. The investigation started with a detailed inventory of selected areas of affected pavements in order to identify and classify the existing types of distresses and select locations for collection of the cores. During the Phase I of the study a total of 36 concrete cores were extracted from 5 different pavements.. During Phase II of the study a total of 18 cores were retrieved from five different pavement sections and subject to examination. The cores were subjected to eighth different tests: air-void system determination, Scanning Electronic Microscopy (SEM) analysis, X-ray diffraction (XRD) analysis, sorptivity test, freeze-thaw & resonance frequency test, resistance to chloride ion penetration (RCP) test and chloride profile (concentration) determination. The test results identified several cases of in-filling of the air voids (especially smaller air bubbles) with secondary deposits. These deposits were most likely the result of the repetitive saturation of air voids with water and substantially reduced the effectiveness of the air voids system with respect to providing an adequate level of freeze-thaw protection. Specifically, it was observed that the existing air void system in the concrete from panels near the deteriorated longitudinal joint had neither spacing factors nor specific surface values within the range recommended for freeze-thaw durability. Contrary to this, nearly all the concrete in lanes without damage had an adequate air void system at the time of sampling. In addition, the affected concrete often displayed an extensive network of microcracks, had higher rates of absorption and reduced ability to resist chloride ions penetration. From the observation of the drains performed using the remote camera it was obvious that not all the drains were functioning properly and some were entirely blocked. However, more precise or direct correlations could not be made between the conditions of the drains and observed pavement performance

Accelerated Test Method to Identify Freeze-Thaw Durability of Aggregates

INDOT currently identifies freeze-thaw durable aggregate using ITM210, a 90-day concrete beam freeze-thaw test. To accelerate this procedure, the 8-day Hydraulic Fracture Test (HFT) was investigated and modified. Samples from 18 quarries and six RCA sources were subjected to HFT and ITM210. Statistical analysis demonstrated that HFT can predict the ITM210 results with reasonable accuracy. The modified HFT procedures and equipment are recommended as a quick screening tool for predicting ITM210 test results

Joint Deterioration in Concrete Pavements

Concrete pavements located in cold climates have been experiencing premature joint deterioration. Entrapment of moisture in the joints saturates the surrounding concrete, rendering it susceptible to freeze-thaw damage. To identify and to isolate the variables that might be causing this localized deterioration, concrete cores were obtained from deteriorated and non-deteriorated sections of US 35, SR 38 and SR 3 located near Indianapolis, Indiana and I-94 (located near Michigan City, Indiana). The visual evaluation of the condition of the pavement revealed that the drainage of the joints contributes significantly to their performance. Specifically, all deteriorated joint core holes drained poorly when compared to well performing joint core holes or mid panel joint core holes. Hardened air void parameters were determined following the procedure described in ASTM C457 and results for cores from deteriorated and non-deteriorated regions of the pavements were compared. The chemical and microstructural changes occurring in concrete were investigated using scanning electron microscope. Concrete panels with poor values of spacing factor and specific surface area were more prone to premature joint deterioration. Visual observation of coring sites on I-94 showed that unsealed joints performed better than sealed joints

Concrete Pavement Joint Deterioration

Concrete pavements are an important part of our national infrastructure. In recent years the relatively small number of reported joints deteriorating prematurely in concrete pavements around Indiana has increased. Changes over the past 45 years in INDOT specification, pavement materials, designs and construction practices, and current de-icing materials were examined and related to the durability of concrete at the joints of existing pavements. A survey of concrete pavements across the state revealed that no pavements from the two southern districts less than 40 years old showed this distress except in more recently placed patches. Cores were retrieved from the joints and mid-panel of 11 pavement sections that represented different materials, ages, construction, deicer exposure, and different levels of deterioration, from non-deteriorated concrete to concrete with severe deterioration at the joints. The pavement base drained well at the mid-panel of most pavements but was reduced at the joints for over half the pavements with the most severe joint deterioration associated with the slowest drainage. None of the concrete had an air void system that met all the criteria recommended for FT durable concrete but was better at the mid-panel than at the joints. Infilling and lining of the entrained air voids with ettringite and some Friedel’s salt was more common near the joints and could account for the reduced air void system. The FT testing did not correlate directly with the air void parameters but generally mid-panel samples did test as more durable than joints. Evidence from the presence of unhydrated cement grains suggested that the concrete at the joint face was not fully cured. One pavement section that did not have fly ash had worse deterioration than the panels nearby that had fly ash and calcium hydrate was more noticeable in the concrete from joints with severe deterioration. Several variables were identified that influence the durability of the concrete at the joints and there may be other variables that were beyond the scope or capacity of this study. In summary this study identified the following variables likely influenced the durability of the concrete at the joints: the drainability of the base at the joints, original air void system, reduced air void parameters due to lining and infilling of the air voids with secondary minerals, poor hydration of the concrete at the joint face and increased moisture at the joint

Nature in the works of Chaucer

This item was digitized by the Internet Archive. Thesis (M.A.)--Boston Universityhttps://archive.org/details/natureinworksofc00sor

Hydraulic Fracture Test to Determine Aggregate Freeze-Thaw Durability

The freeze-thaw durability of carbonate aggregates can vary greatly from durable to highly susceptible to freeze-thaw distress. Using nondurable aggregate in concrete pavement exposed to freeze-thaw cycles may lead to serious distress and greatly decrease the pavement’s service life. The testing needed to identify freeze-thaw durable aggregates can take several months to complete. The main objective of this study was to develop a reliable, quick test method for determining the freeze-thaw resistance of carbonate quarried aggregates in Indiana using the Hydraulic Fracture Test (HFT) equipment. Aggregate samples collected from 18 quarried carbonate sources from across Indiana that represented a range of freeze-thaw performance were subjected to HFT using the existing MnDOT HFT equipment and the newly developed INDOT HFT equipment. Aggregates from the same sources also were used to produce concrete beams that were subjected to the INDOT modified AASHTO T161-B freeze-thaw test (ITM 210) which evaluates the dilation of concrete beams exposed to freeze-thaw cycles. The experimental data were analyzed statistically and linear regression models were developed to predict the average percent dilation and the durability factor of freeze-thaw test beams using parameters obtained from HFT results. Comparing the modeled and measured test results, the favored model predicts dilations based on the INDOT HFT results. These modeled dilations, when compared to measured dilations gave an adjusted R2 value of 0.85, indicating the model has a high degree of certainty. The modified INDOT HFT equipment, refined test procedures and data analysis developed during this study are recommended as screening tools for predicting AASHTO T161/ASTM C666 FT test results in 8-days. Further testing is recommended to refine and validate the models before they are fully implemented as an acceptance standard

Winter Food Habits and Preferences of Northern Bobwhites in East Texas

During late winter, 1994 and 1995, we investigated food habits and preferences of northern bobwhites (Colinus virginianus; hereafter, bobwhites) collected on forested lands in east Texas. Crops for bobwhites were collected from areas under 3 management regimes, namely intensively managed for bobwhites (QMA) (i.e., tree basal area reduced, annually burned, numerous multi-stage food plots, etc.), extensively managed for timber and wildlife (NBS) (i.e., burned every 3-5 years, scattered 2-stage food plots with corn feeders), and unmanaged for wildlife (i.e., burned every 5-7 years). With years pooled, partridge pea (Cassia fasciculata), Hercules club (Zanthoxylum clava-herculis), and pine (Pinus spp.) seeds, and clover leaflets (Trifolium spp.) comprised 93% by weight of foods of 79 bobwhites foods on QMA. On NBS, 81% of 40 bobwhite diets was butterfly pea (Centrosema virginianum), browntop millet, pine, wild bean (Strophostyles spp.), and corn seeds and clover leaflets; millet and corn were from food plots and feeders, respectively. For unmanaged areas, 79% of 19 bobwhite diets was butterfly pea, rush (Juncus spp.), pine, partridge pea, and American beautyberry (Callicarpa americana) seeds, and clover leaflets. Top-ranked food items on QMA were pine

Winter Food Habits and Preferences of Northern Bobwhites in East Texas

During late winter, 1994 and 1995, we investigated food habits and preferences of northern bobwhites (Colinus virginianus; hereafter, bobwhites) collected on forested lands in east Texas. Crops for bobwhites were collected from areas under 3 management regimes, namely intensively managed for bobwhites (QMA) (i.e., tree basal area reduced, annually burned, numerous multi-stage food plots, etc.), extensively managed for timber and wildlife (NBS) (i.e., burned every 3-5 years, scattered 2-stage food plots with corn feeders), and unmanaged for wildlife (i.e., burned every 5-7 years). With years pooled, partridge pea (Cassia fasciculata), Hercules club (Zanthoxylum clava-herculis), and pine (Pinus spp.) seeds, and clover leaflets (Trifolium spp.) comprised 93% by weight of foods of 79 bobwhites foods on QMA. On NBS, 81% of 40 bobwhite diets was butterfly pea (Centrosema virginianum), browntop millet, pine, wild bean (Strophostyles spp.), and corn seeds and clover leaflets; millet and corn were from food plots and feeders, respectively. For unmanaged areas, 79% of 19 bobwhite diets was butterfly pea, rush (Juncus spp.), pine, partridge pea, and American beautyberry (Callicarpa americana) seeds, and clover leaflets. Top-ranked food items on QMA were pine, hairy vetch, and Hercules club seeds in 1994 and butterfly pea, partridge pea, and wax myrtle (Myrica cerifera) seeds in 1995 (P \u3c 0.05). On NBS, hawthorn (Crataegus spp.) and beautyberry seeds were top-ranked in 1994 as were kobe lespedeza, wild bean, and butterfly pea seeds in 1995. On unmanaged areas, butterfly pea and partridge pea seeds and clover leaflets were highest ranked in 1995. On forested lands, activities (e.g., disking, burning, establishing food plots) which provide seed-bearing plants, especially legumes, and clover greenery benefit bobwhites

Using Recycled Concrete as Aggregate in Concrete Pavements to Reduce Materials Cost

The main objective of this project was to evaluate the effects of using aggregate produced from crushed concrete pavement as a replacement for natural (virgin) coarse aggregate in pavement mixtures. A total of ten different concrete mixtures containing recycled concrete aggregate (RCA) were designed to meet the requirements of Indiana Department of Transportation (INDOT) specifications. These included three different RCA replacement levels (30%, 50% and 100% by weight of the natural coarse aggregate) and two different cementitious systems (plain system – Type I portland cement only and fly ash system – 80% of Type I portland cement and 20% of ASTM C 618 Class C fly ash). The scope of the project included the evaluation and comparison of several properties of RCA and natural aggregates, evaluation and analysis of the effects of RCA on concrete properties, and modification of aggregate gradations and mixture composition in an attempt to improve the properties of RCA concrete. All ten mixtures were first produced in the laboratory (trial batches) and were subsequently reproduced in the commercial ready-mixed concrete plant. Each mixture produced in the ready-mixed plant was used to prepare several types of specimens for laboratory testing. The tests performed on fresh concrete included determination of slump and entrained air content. The mechanical properties of the hardened concrete were assessed by conducting compressive strength, flexural strength, modulus of elasticity and Poisson’s ratio tests. Concrete durability was assessed using a wide array of measurements, including: rapid chloride permeability (RCP), rapid chloride migration (RCM), electrical impedance spectroscopy (EIS), surface resistivity, free shrinkage, water absorption test, freeze-thaw resistance and scaling resistance. The test results indicated that the properties of plain (no fly ash) concrete mixtures with 30% RCA as coarse aggregate were very comparable to (in some cases even better than) those of the control concrete (0% RCA). Although mixtures with 50% RCA showed a reduction in durability and mechanical properties of up to 36%, the test results still met INDOT’s specifications requirements. The mechanical properties of plain concretes made with 100% RCA were measurably lower (16%-25%) than those of the control concrete. It should be pointed out, however, that these properties were still above the minimums required by INDOT’s specifications except for one mixture in which the w/c was increased to 0.47 to achieve workability. The use of fly ash improved the strength and durability of RCA concrete, especially at later ages. In particular, the properties of concrete with 50% RCA coarse aggregate were similar to the properties of control concrete. Similarly, the mechanical and durability properties of the mixture with 100% RCA coarse aggregate and 20% fly ash were better than those of a similar mixture prepared without fly ash. Even though, when compared to the fly ash concrete with 100% virgin aggregate the mechanical and durability properties of the 100% RCA concrete were up to 19% and 35% lower, it still met minimum requirements imposed by INDOT’s specifications. Once the testing of the original ten types of concrete mixtures was completed, six additional concrete mixtures were developed and produced in the laboratory using aggregate with a modified gradation (with respect to the gradation of the aggregates used in the original mixtures). These mixtures were used to study whether the virgin and RCA aggregates can be used in different proportions to produce an “optimized blend” which will improve one (or more) of the concrete characteristics. The test results obtained from the six additional mixtures indicated that modifying the aggregate gradation did not have beneficial effects with respect to either compressive or flexural strength values. This failure to improve concrete strength with modified aggregate gradation may have been due, at least in part, to the quality of the source of aggregate that was used to modify the gradation. Considering the limited scope of this study (only one source of RCA and two natural aggregate sources were used), it is recommended that the amount of RCA coarse aggregate be limited to 30% in plain concrete and to 50% in fly ash concrete to ensure the adequate quality of the pavement concrete