Highway Research Board Research Articles

Geotechnical Suitability of Soils in Road Construction for Sustainable Development in Tropical Africa: Case of Lateritic Graveled Soils of Bandjoun (West, Cameroon)

The environmental impact of the exploitation of geomaterials and their relatively high cost, coupled with the increasingly low financial capital in developing countries, are pushing road actors to turn to inexpensive local ecological materials. The present study is conducted on lateritic graveled soils of Bandjoun (LGSB) in the West Cameroon Region. The aim is to determine whether lateritic gravel soils, particularly those in Bandjoun, can be an ecological and economical alternative to rock aggregates in road construction, considering their geotechnical parameters and environmental impact. These soils were described in the field and were also subjected to complete geotechnical identification in the laboratory. The LGSB presents Californian bearing ratio indices ranging from 26% to 83.3%, a plasticity index of 10.11%, a fines content of 12.05%, an average methylene blue value of 4.25, a water content at the Proctor optimum of 27.6% and a dry density of 1.75 g/cm3. They are silty or clayey gravels and sands of subgroup A-2-7 according to the Highway Research Board classification; sandy and gravelly soils with fines of class B according to the classification of the Road Construction Guide; and silty gravels according to the classification of the Central Laboratory of Bridges and Highways. These soils can be used naturally in pavement layers, in particular in subgrade for all traffic classes and in subbase for low traffic. The tonnage of these soils has been estimated at 18,389 t. The global warming index shows that the use of these soils (18,389 t) in road construction can reduce 31,629–62,706 kg of carbon emissions. The use of lateritic soils in road construction is a very interesting alternative to reduce the environmental impacts associated with the manufacture of rock aggregates. So, lateritic soils should be used instead of rock aggregates for cleaner, more environmentally friendly road construction. The present work presented a specific evaluation of the geotechnical properties and ecological impact of lateritic graveled soils for road construction, as well as their potential for ecological and economic utilization.

Correction of the granulometric curve of fine soil using ash from the burning of sugarcane bagasse

In road works, there are cases in which natural soils have inadequate characteristics for their intended use, especially clayey or fine ones, which leads to the need to find stabilization methods that allow the soil to present itself as a suitable material for its application. Thus, the ash, residue generated in the sugar and alcohol industry from the burning of sugarcane bagasse and which often does not have an adequate destination, becomes an attractive material due to its granulometry and chemical composition. Thus, the objective was to study the feasibility of correcting the granulometric curve of the fine soil from Maringá-PR with the addition of sugarcane bagasse ash, seeking to analyze the influence of this correction through granulometric analysis, particle density, limit of liquidity and plasticity, Unified Soil Classification System (USCS) and Highway Research Board Classification (HRB) and compaction curve. The results showed that the incorporation of ash in the fine soil remodeled the granulometric curve, making it similar to that of a sandy soil. According to the HRB and USCS classifications, the soil was shown as an A-7-5 soil or high compressibility silt and the mixture as an A-6 soil or clayey sand. There was also a reduction in the group index, in the limits of liquidity and plasticity, as well as in the optimal compaction moisture. Therefore, the addition of ash to the soil resulted in an increase in texture quality and plasticity. Since, for road applications, a correlation was found between the addition of ash and the increase in the quality of the mixture as a subgrade material.

Evaluation of lateritic soils of Mbé for use as compressed earth bricks (CEB)

This work was carried out on the lateritic soils of Mbé in the Adamawa region of Cameroon. For this study, twenty (20) soil samples were taken from four (04) sites (Kabaa, Ndom, Mbé Norwegian camp, and Nyéssé). To assess their suitability for the production of compressed earth bricks, physical parameters were obtained by geotechnical tests to determine particle size distribution, water content, atterbergs limits, specific gravity, methylene blue value, maximum dry density (MDD), and optimum moisture content (OMC). Chemical and mineralogical properties were obtained by X-ray fluorescence and X-ray diffraction, respectively, followed by the determination of technological parameters (water absorption and mechanical properties) on compressed earth brick specimens. The results show that the studied lateritic soils contain mainly sand (52.8–90.3 wt%) and clay particles (8.4–42.1 wt%), gravel particles are slightly represented (1.1–16.3 wt%). The plasticity index of the studied materials is average (5–38%), about their methylene blue values (1–5), these soils correspond to clayey-silty soils. The materials studied are classified by the USCS as clayey sands/silty clays; according to the Highway Research Board (HRB), they are classified as A-7-5 or A-7-6 clayey soils with group index of 1 for Kabaa, 7 for Ndom, 9 for Mbé Norwegian Camp, and 12 for Nyéssé. These soils are rich in silica (SiO2, 62.6–78.1 wt%), followed by aluminum (Al2O3, 11.8–18.2 wt%) and iron oxides (Fe2O3, 3.2–8.1 wt%); other oxides are in lower proportions (<1 wt%). The mineralogical content consists mainly of clay minerals such as kaolinite, illite, smectite (montmorillonite), and non-clay minerals such as quartz, muscovite, biotite, gibbsite, and hematite. The bulk density and mechanical properties of the specimens are within the standard NC 102-115 (2007) of compressed earth bricks (CEB), which recommends minimum compressive strengths of 2 Mpa for unstabilized CEB and 4 Mpa for stabilized CEB. Water absorption of CEB and physical parameters of soils have a significant impact on the mechanical behavior of CEB. According to the test results, Mbe lateritic soils are suitable for engineering applications in the production of stabilized compressed earth bricks.

The Role of Electrochemistry and Mineralogy in the Geotechnical Behavior of Salinized Soils

The Atterberg limits are essential information and the first step in soil classification for geotechnical purposes. Established laboratoryprocedures use distilled water in the plasticity and liquid limits determination. However, saline solutions frequently interact with soilsin the construction environment through fluid percolation processes. This work aims to understand the variation of the geotechnicalbehavior of two standard materials with different mineralogical compositions (kaolinitic and smectitic) when affected by NaCl ionicsolutions in different concentrations. The purpose is to simulate different soils in environments with the presence of saline solutions.This paper reports an experimental program in which a kaolinite-rich and a smectite-rich material received NaCl solutions in threedifferent concentrations (0.6 %, 3.5 %, and 15.0 %) and had their Atterberg limits determined under these conditions. Additionally,non-contaminated samples of both materials have had their limits measured using distilled water. Physical characterization testsincluded hygroscopic moisture, grain size distribution, grain density, plastic limit (PL), and liquid limit (LL). These data allowed thedetermination of the Skempton activity index (AI), plasticity index (PI), consistency index (CI), classification of soils in the UnifiedSoil Classification System (USCS), and in the Highway Research Board (HRB) with the group index (GI). Mineralogy was determinedby X-ray diffraction and physical chemistry by measuring pH in H2O and KCl, determining the ΔpH, the point of zero-charge (PZC),and the surface electrical potential (Ψo). The results show that the pH values rise with increasing salinity, while ΔpH, PZC, Ψo, LL,AI, PI, GI decrease with increasing salinity. The PL decreases with the increase in salinity for smectite and increases for kaolinite. TheUSCS and HRB demonstrate that the materials start to behave as fewer plastic materials with increased salinity. It is concluded that thevariations in the physicochemical parameters of the environment control and modify the geotechnical behavior of the fine-grained soils.

Application of Fuzzy Rule based System for Highway Research Board Classification of Soils

Fuzzy rule-based model is a powerful tool for imitating the human way of thinking and solving uncertainty-related problems as it allows for understandable and interpretable rule bases. The objective of this paper is to study the applicability of fuzzy rule-based modelling to quantify soil classification for engineering purposes by qualitatively considering soil index properties. The classification system of the Highway Research Board is considered to illustrate a fuzzy rule-based model. The soil's index properties are fuzzified using triangular functions, and the fuzzy membership values are calculated. Fuzzy arithmetical operators are then applied to the membership values obtained for classification. Fuzzy decision tree classification algorithm is used to derive fuzzy if-then rules to quantify qualitative soil classification. The proposed system is implemented in MATLAB. The results obtained are checked and the implementation of the proposed model is measured against the outcomes of the laboratory tests.

Soil Stabilization using Geosynthetic Material (Steel Fibres)

Soil stabilization is the process which involves enhancing the physical properties of the soil in order to improve its strength, durability etc. by blending or mixing with additives. The different types of method used for soil stabilization are: Soil stabilization with cement, Soil stabilization with lime, Soil stabilization using bitumen, Chemical stabilization and a new emerging technology of stabilization by Geo textiles and Geo synthetic fibers. In this study, we are making use of Steel fibers as geo synthetic material for stabilization of soil. With the introduction of Steel fibers to the soil the CBR values will improve and thickness of pavement layer also gets reduced. It also reduces the intensity of stress on subgrade. Steel fibers is such a geosynthetic material which is effectively accessible, ecofriendly and furthermore savvy. With the use of soil adjustment strategy in development the general expense gets diminished when contrasted with the normal technique for development. The Highway Research Board (HRB) order of the dirt strata like dark cotton soil and sedu soil is finished utilizing appropriate examining system, for example, Core Cutter Method. To decide the attributes like Grading by Sieve Analysis, Atterbergs Limits i.e Liquid farthest point utilizing Cone Penetration Method and Casagrande Method, Plastic breaking point by rolling the example to 3mm breadth string, Shrinkage limit utilizing Shrinkage mechanical assembly, Optimum Moisture Content and Maximum Dry Density utilizing Standard Proctor Test and furthermore California Bearing Ratio by leading CBR test. The pavement thickness was designed using pavement design catalogues published by IRC SP:20-2002. The estimation for the road is done by considering the item such as Jungle Cutting, Earthwork Excavation for Roadway and Drains, compacting and grading etc., as per SR 2016-17, PW, P and IWT circle Dharwad and suggestion of specification for the mixture of Steel fibers as Geo Synthetic material for stabilization using CBR value by CBR Test and Shear strength using Unconfined Compression Test. The different tests were conducted in order to determine the different characteristics and properties of the black cotton soil and obtained with following results. The liquid limit of the soil with addition of Steel fibers was found to be decreasing when compared to liquid limit of soil alone. The plastic furthest reaches of the dirt diminished with the expansion of filaments. The shrinkage furthest reaches of the dirt was expanded with increment in strands. The MDD of the dirt with expansion of Steel filaments by weight of soil is observed to increment upto 0.75% after that it diminishes and the comparing OMC is diminished with expansion of strands. The shear quality of soil diminished significantly with expansion of strands. The CBR estimation of the dirt expanded significantly. The distinctive tests were led so as to decide the diverse qualities and properties of the sedu soil and acquired with following outcomes. The fluid furthest reaches of the dirt alone was observed to be 36.5%. The MDD of the dirt with expansion of 0.25%, 0.5% Steel strands by weight of soil is observed to be diminished by 0.83% and 0.75% , 1.0% Steel filaments by weight of soil is observed to be expanded by 0.11 % and 16.98% separately and the relating OMC is diminished by 15.62%, 21.87% and 33.75% individually. The shear quality of the dirt with the expansion of 0.25%, 0.5%, 0.75% and 1% of Steel strands is observed to be diminished by 38.57%, 38.57%, 35.25% and 5.85%. The CBR estimation of the dirt with expansion of 0.25%, 0.5%, 0.75% and 1.0%, Steel filaments by weight of soil is observed to be expanded. From the restricted research center investigation directed we reasoned that the 0.75% of Steel fiber can generously improve the properties of Black cotton soil. Furthermore, in this way 0.75% of Steel fiber is the ideal fiber content for dark cotton soil. The design thickness of flexible pavement before stabilization is obtained as 450mm and after stabilization is obtained as 250mm.The estimated cost for constructing flexible pavement before stabilization of soil is obtained as 4018050 Rs /Km and after stabilization of soil is obtained as 3721894Rs/Km. The estimated cost after stabilization is found to be decreased by 7.37%.

Two-tier data fusion method for bridge condition assessment

Fusing collected inspection data provides comprehensive and relatively more accurate diagnostics of defects and accordingly more accurate condition assessment of structures. This paper presents a new two-tier method that utilized data fusion methods for condition assessment of reinforced concrete bridge decks. The method utilizes pixel and feature levels fusion of data collected from multiple nondestructive evaluation (NDE) methods such as ground penetrating radar, impact echo, half-cell potential, and electrical resistivity. Data and measurements of NDE methods are extracted from the Iowa Highway research board project 2011 report for three case studies. It is observed from the three cases that each level of data fusion has its unique advantage. The power of pixel level fusion lies in its ability to provide an overview of bridge deck deterioration in one map as it appears in the fused image. On the other hand, feature fusion works better when only specific types of defects such as corrosion, delamination, and deterioration captured from inspection carried out by each of technologies referred to above. The proposed method is tested against filed inspection methods and core sample results described in the three case studies. The main findings of this research recommend utilizing data fusion in two levels as a new method to facilitate and enhance the confidence and capabilities of inspectors in interpretation of the NDE test results.

Performance of Concrete Overlays in Iowa

It has often been claimed that concrete overlays are a cost effective, low maintenance preservation tool used to extend pavement life. However, there has been relatively little data to confirm this. The State of Iowa has a long history of using concrete overlays as a means of extending the life of all types of roadways and as such provides an interesting opportunity to examine their performance over time. The work described in this paper summarizes the activities and findings of a study conducted for the Iowa Highway Research Board. Existing databases operated by the Department of Transportation and Iowa State University were analyzed to assess the performance of overlays. Pavement condition data such as IRI, transverse cracking, longitudinal cracking, D-cracking, spalled joints and faulting were compared with design details of the overlays such as bond type, thickness and joint spacing. The data indicate that in general overlay performance is very good in that about 90% of 3100 km of overlays are still in acceptable condition at ages up to 35 years. The paper discusses the details behind this finding.

Calibration and Validation of a Swedish Space-time Analytical Model

The present capacity models for freeways descended from the early 70th, and were partly using the HCM 1965 Highway Research Board (1965) as background. Not especially valid for the todays freeway network. During the last decade one large project, Traffic Performance on Major Arterials (TPMA) Carlsson et al. (2000a), Carlsson et al. (2000b) and Carlsson et al. (2002) has been implemented. New models for basic freeway segment, merging and weaving segment was developed. A new model for weaving were developed 2010 with new empirical data Strömgren (2011). In addition to the manual calculation method for not oversaturated condition a time-space model that also handled oversaturated conditions has been included.The development of the model started with analysis of video and aerial photo to be able to calculate the jam density, the last point in the oversaturated regime curve. The oversaturated flow-density curve has been developed using the density at capacity for a certain cross section and speed limit based on empirical data of flow and density in oversaturated conditions including jam density.The development of the Swedish space-time model used FREEVAL Transport research Board (2010). The resulting computer model, called CALMAR, CALculation of performance for Motorway ARterial facilities, was built in VB.NET and VBA. Calibration of the model was done by using the Swedish capacity models for link, merging, diverging and weaving but also flow-density estimations. All other country specific parameters as speed limits etc. was set to Swedish conditions. A traffic environmental factor was implemented describing the environment where the freeway is situated, and divided into rural or urban. Urban conditions has an interchange density higher or equal to 0.5 (interchanges/km), rural conditions has a density lower than 0.5 (interchanges/km).The model was calibrated for four and six lane freeways with merging or weaving lanes. The speed limit range from 70 kph to 120 kph in step of 10 kph. The model has its limitations. Lane width, shoulder width, distance to obstacles, gradients for ramps and length of merging was not taken into account, since no relationship could be found in the empirical data.The validation of the model was carried out for three different cases on the A4 freeway south of Stockholm, one accident, one vehicle break down and one at oversaturated condition due to high demand flow. Recorded flows from the motorway control system (MCS) as well as the automatic incident detection (AID) data from this system were used to identify queue increases and decreases. Reports from the roadside assistance team were also used to identify the degree and duration of bottleneck blockade.A careful collection of flows including bottleneck throughput and upstream demand were collected in the cases of accidents. The throughput and the upstream flow (demand) on the upstream not affected link before the end of the queue were registered for each time step (60minutes). The throughput flow was used as the capacity value in CALMAR, and the demand flow upstream as the segment demand. This was repeated for each time step of 60minutes. In the case with oversaturated condition no explicit change of the capacity in the bottleneck was done. The capacity was indirectly changed by the related interchange, where the number of lanes was changed from 3 to 2 lanes and the speed limit decreased from 100 kph to 80 kph. The demand flow was captured as in the two first cases.To estimate the queue length AID data was collected from the MCS database and converted from binary to decimal format. Data from 12 MCS gantries for each accident in the southbound direction, and 18 gantries in the northbound direction were collected. The average gantry spacing was 200-300 m.For each time step the end of the queue was registered as a length from the bottleneck where the AID alarm was registered. The AID gives a sign of 30 kph without flashing lamps and has a threshold of 22 kph. This means that the speed is in the range of 0 to 22 kph. A check is also done in the speed flow data from the MCS, if speed less than approximately 10 kph the density is too high for the radar detectors and no data will be recorded.The result from the validation showed a good fit. The CALMAR model gives in case 1, southbound accident, a maximum queue length of 2472 m and the maximum empirical queue length was 2635 m. Case 2, northbound vehicle breakdown gave a CALMAR queue length result of 3608 m compared to a maximum empirical queue length of 3530 m. Case 3, northbound oversaturated condition, gave a CALMAR result of 4149 m queue length and an maximum empirical queue length of 4310 m.

English

s: Generally the soil quality improvements through stabilization include better soil gradation, reduction of plasticity index or swelling potential, and increases in durability and in strength. The tensile strength and stiffness of a soil layer can be improved through the use of additives and thereby permit a reduction in the thickness of the stabilized layer and overlying layers within the pavement system. According to Sherwood (1995) and Little (1999), lime stabilization can be used to either modify or stabilize clays. The strength of lime mixture depends to a great extent on the quantity of lime added above lime fixation point. (i.e. it changes the Plasticity Index of soil). In this experiment Indian A-7a type black cotton sol is used. In this paper soil subgrade characteristics are determined by using 0%, 2%, 4%,6%, 8%, 10%, 12%, lime ( by weight of soil) stabilization techniques & a graphical representation is made % of stabilization Vs optimum moisture content & maximum dry density values. But some time in the field OMC of soil, especially black cotton soil changes very rapidly in this case the advantage of this graph is one can easily get a rough idea about changes soil characteristics due to applications of lime stabilization, when the soil becomes highly plastic to non plastic. Finally a semi empirical formula is made to get an idea about OMC & Maximum Dry Density values of A-7a type Indian black cotton soil (As per Highway Research Board of India) due to application of lime stabilization within range of 0 to 12% of lime by weight of soil. This paper also help full to determine how the subgrade strength varies with lime stabilization. KYE WORDS: Sub-grade Soil Stabilization, Lime Stabilization, Changes in Soil Characteristics due to Lime Stabilization, Establishment of Semi Empirical Formula, Limitations

Tribute to Dr. Reynold K. Watkins: Pioneer in Pipeline Technology Advancement

The pipeline engineering profession owes much to Dr. Reynold K. Watkins, a professional engineer and professor emeritus of engineering at Utah State University (USU), where he has served on the faculty since July 1, 1947, shortly after graduating from Massachusetts Institute of Technology (MIT) with a master’s degree. Inspired by his Professor John Benson Wilbur, who was a consultant for the design of the Cape Cod bridges, his early aspirations revolved around designing bridges. However, the nation was still recovering from World War II, and bridges were of low priority, so he joined the faculty of Utah State Agricultural College, where the emphasis was on water distribution in the arid Great Basin. Beside his teaching assignments, he was asked to assess irrigation canals and found that canals lost a third of the flow per mile due to evaporation, percolation, plants along the banks, and rodent burrows. Even more depressing was the loss of children who drowned in irrigation ditches. Could pipes reduce the losses? He took a sabbatical leave to study buried pipes under Merlin Grant Spangler at Iowa State College. He completed his Ph.D. in 1957. In the 1960s, Dr. Watkins chaired the Culvert Committee of the Transportation Research Board. His reputation as an expert on underground pipeline construction led DuPont Corp. to seek his assistance in investigating the potential for deploying buried high-density polyethylene (HDPE) pipelines. He also conducted studies and tests on flexible buried pipes for many pipe associations, as well as pipe manufacturers and pipelining providers. In 1986, Dr. Watkins was named outstanding engineering educator at USU. He received the prestigious American Society of Civil Engineers Pipeline Division Stephen D. Bechtel Pipeline Engineering Award in 1988. In 1997, he received the Industry Pioneer Research Award from the Corrugated Polyethylene Pipe Association. Subsequently, in 1999, Dr. Watkins was the recipient of the inaugural presentation of the Reynold K. Watkins Award for lifetime achievement in the research and design of buried pipes by the Pipe Rehabilitation Council. In 2006, he received the Distinguished Service Award from the Steel Tank Institute and Steel Plate Fabricators. During his tenure at USU, Dr. Watkins served as an associate director of the Engineering Experiment Station and head of the mechanical engineering department. He also served on the state and national engineering committees and as a consultant to manufacturers, engineers, and users of buried pipes and tanks, on both national and international fronts. Hundreds of professionals have attended his Piping Systems Institute for practicing engineers conducted annually at USU for several years. He founded Utah State’s Buried Structures Laboratory and served as the laboratory’s first research director. Dr. Watkins coauthored with Dr. L. R. Anderson Structural Mechanics of Buried Pipes (Watkins and Anderson 1999). He also coauthored with Dr. O. K. Shupe Introduction to Experimentation, USU Engineering Experimentation Station, a 1976 text for graduate students (Watkins and Shupe 1976). His Getting Research Findings into Practice, NCHRP Synthesis of Highway Projects 20–5, Topic 11, was published by the U.S. government’s Highway Research Board (Watkins 1974). He is a contributor to the recent ASCE Manual of Practice (MOP) 119, Buried Flexible Steel Pipe Design and Structural Analysis (Whidden 2009), where the most current work of Dr. Watkins and others is presented to develop external loading design concepts. Dr. Watkins has 54 refereed papers on structural performance of buried pipes published in technical journals. He has served as a guest lecturer for different universities (see Figs. 1 and 2) and directed many short courses in the United States and around the world. His books and papers have set the standards for underground pipeline construction, maintenance, and performance, making these structures more dependable and safer. For many years, he has been

Fifty Years of TRB Bridge Committees

The first bridge committee in the Highway Research Board was organized in 1949 in the Department of Highway Design. Today, 11 TRB committees deal with bridges and related structures. Historical development of the organization of bridge committees is described first. Discussion of their accomplishments follows under the headings of annual meetings, publications, research, conferences, and management workshops. It is concluded that TRB bridge committees serve today as the principal catalyst for bridge research in the United States.

New Specification of Material for Surfacing Unpaved Roads

To develop a new specification of material for surfacing unpaved roads, an experiment was conducted on 41 unpaved road sections located in five different physiographical regions in the state of Rio Grande do Sul, Brazil. The behavior of the sections under observation was analyzed qualitatively to evaluate the performance of the applied surfacing material. Because the traditional soil classifications (Highway Research Board and Unified Soil Classification System) are not suitable for classifying tropical soils, a new classification, namely MCT (miniature, compacted, tropical), developed in Brazil in 1981 was adopted as a basis for material selection. The behavior parameters observed were support, frictional resistance, and durability. The results obtained led to the specifications presented here, which were tested during a doctorate research program developed between 1991 and 1996 conducted by the first author and supervised by the second. It was concluded that the proposed specification based on the MCT classification system is more adequate than the ones previously used based on traditional classifications. The “binder content” of soils, a measure similar to that used for bituminous materials (asphalt binder content) is introduced to evaluate the agglomerating capacity of the fine fraction and, therefore, the material durability.

Prediction of stresses in concrete pavements subjected to non-linear gradients

This paper presents a technique for analyzing the residual stresses in concrete pavements subjected to non-linear (stress or strain) gradients throughout the slab thickness. The analysis is separated into two parts. In the first part, an expression is presented for calculating the self equilibrated stresses within a cross-section due to internal restraints (i.e. satisfying equilibrium conditions and continuity of the strain field within the cross-section). These stresses are independent of slab dimensions and boundary conditions. In step two, the stresses due to external restraints (i.e. self-weight and subgrade reaction) are calculated using an equivalent linear temperature gradient obtained from the first part and using existing closed form solutions by Westergaard [Westergaard, H. M., Computation of stresses in concrete roads. In Proc. of the 5th Annual Meeting, Vol. 5, Part I, Highway Research Board, 1926, pp. 90–112] or Bradbury [Bradbury, R. D., Reinforced Concrete Pavements. Wire Reinforcement Institute, Washington D.C., 1947.]. The solution to this step includes slab length and boundary conditions. Total internal stresses due to non-linear gradients are obtained using the superposition principle. The proposed method has been applied to field data from another study for varying temperature profiles within a 24 h period and compared to results from conventional analysis assuming linear gradients. Significant differences were found between the two methods for night-time and early-morning conditions. A linear gradient solution sometimes underestimates tension in the bottom of a slab prior to vehicle loading by a factor of three.

Lime modification of problem laterite : Engng Geol V30, N2, April 1991, P141–154

Abstract An investigation into the potentials of modifying problem laterite using hydrated lime is presented. Details of test methods and materials are given. Results presented show that problem laterite classified as A-7-6 soil can be modified with 3% lime using the grain-size and plasticity criteria of the Highway Research Board limits for soils that can be stabilized with Portland Cement. Results presented also indicate that using only the plasticity criteria, the soil can be modified with 2% lime.

Lime modification of problem laterite

An investigation into the potentials of modifying problem laterite using hydrated lime is presented. Details of test methods and materials are given. Results presented show that problem laterite classified as A-7-6 soil can be modified with 3% lime using the grain-size and plasticity criteria of the Highway Research Board limits for soils that can be stabilized with Portland Cement. Results presented also indicate that using only the plasticity criteria, the soil can be modified with 2% lime.

The History of Frost Research in Minnesota

Frost research in Minnesota dates back to the late 1920s, when the Minnesota Highway Department investigated the causes of frost heaves and frost boils and methods of mitigating associated problems. State highway engineers pioneered in determining the timing and amount of spring‐thaw weakening in pavements and load limitations to minimize damage. The work of committees of the Highway Research Board in such efforts and on other frost problems is reviewed. Research work at the University of Minnesota in the late 1940s for the U.S. Army Corps of Engineers on the thermal properties of soils produced results that are still in widespread use. Graduate students' thesis subjects include a number of cold climate problems. One 1933 thesis was a study of a variety of treatments for frost heave, some of which are utilized at present. Current or planned activities in Minnesota include a Cold Weather Resource Center intended to assist agencies wishing to test products, a Cold Climate Building Research Center, and a Cold Regions Pavement Research Test Facility.

Accuracy and precision of an X-ray diffraction method for analysing portland cements

An X-ray diffraction method for analysing portland cement is described and the accuracy and precision determined. Over 200 cements have been analysed using a method which is a modification of that developed by Berger et al (Highway Research Board Special Report 90 234–253 1964). The accuracy of the compound composition determined by this method is similat to that obtained by the Bogue method. Because of the speed of analysis (17 samples can be analysed in a working day) it is suitable for routine analysis.

The Engineer and Minority Community in Symbiosis

Papers from two Highway Research Board Conferences in 1973 are cited to illustrate new styles in planning for engineering projects. Citizen participation is viewed as the key to public support. Minority communities have developed power to stop unwanted projects. Lacking sophisticated technical information, they have not yet developed the power to push viable alternatives. Informed participation is needed. A recent ASCE paper proposed public service committees within ASCE to offer technical help to minority group leaders. The need is discussed in terms of specific local development issues in the San Francisco region. The idea of public service committees is supported, with some thoughts on alternative forms. The service is only useful if the engineering advice is carefully developed by conscientious professionals. A field of activity exists for starry-eyed and hard-headed engineers.

Urban noise impact

Environmental noise data, including 24-hour noise surveys, taken at various urban locations throughout the United States have been compiled and compared. The data were taken from the open literature and also from the files of the U.S. Department of Housing and Urban Development. It is suggested that the urban noise scene is sufficiently different from the nonurban situation so that, prediction and evaluation schemes commonly used in environmental impact statements are impractical or invalid. For example, relatively sophisticated approaches to traffic noise impact, e.g., the Highway Research Board's design guide (Rep. 117), prove to be intractable for moderately sized projects in urban areas. However, an analysis of the data infers alternate approaches and these are discussed.