TCVN 8859 : 2011 is edited by Institute of Traffic Technology and Science, MOT requested to be appraised by General Department of Standardization, Metrology and Quality, published by Ministry of Technology and Science. TCVN 8859 : 2011 được chuyển đổi từ 22TCN 33406 theo quy định tại khoản 1 Điều 69 của Luật Tiêu chuẩn và Quy chuẩn kỹ thuật và điểm a khoản 1 Điều 7 Nghị định số 1272007NĐCP ngày 182008 của Chính phủ quy định chi tiết thi hành một số điều của Luật Tiêu chuẩn và Quy chuẩn kỹ thuật. TCVN 8859 : 2011 do Viện Khoa học và Công nghệ Giao thông Vận tải biên soạn, Bộ Giao thông Vận tải đề nghị, Tổng Cục Tiêu chuẩn Đo lường Chất lượng thẩm định, Bộ Khoa học và Công nghệ công bố.
NATIONAL STANDARD TCVN 8859 : 2011 AGGREGATE BASES AND SUBBASES OF PAVEMENT STRUCTURE – MATERIAL, CONSTRUCTION AND ACCEPTANCE Graded Aggregate Bases and Subbases Pavement - Specification for Construction and Acceptance CONTENTS Scope of appliance Reference material Terminology, definition Classification Scope of usage of graded aggregates Technical requirements for graded aggregates Construction requirement Inspection, acceptance requirement Regulation of safety and environment protection Preface TCVN 8859 : 2011 is modified from 22TCN 334-06 according to article item 69 of Technical standard and typical and item a article Decree No 127/2007/NĐ-CP dated 1/8/2008 of the Government regulation of detail appliance of Technical standard and typical TCVN 8859 : 2011 is edited by Institute of Traffic Technology and Science, MOT requested to be appraised by General Department of Standardization, Metrology and Quality, published by Ministry of Technology and Science NATIONAL STANDARD AGGREGATE BASES AND SUBBASES OF ROAD STRUCTURE – MATERIAL, CONSTRUCTION AND ACCEPTANCE Graded Aggregate Bases and Subbases Pavement - Specification for Construction and Acceptance Scope of appliance 1.1 This standard defines the technical requirements for materials, construction technology and acceptance of aggregate bases and subbases (CPĐD) of pavement structure 1.2 This standard does not apply to the foundation of natural aggregate such as: aggregate of bee-gravel and red gravel, aggregate o hill gravel and stream gravel (pebbles) and aggregate of blast furnace slag… Reference material The following documents are needed to apply this standard For the reference material which marked with published year, shall be applied by the mentioned document For the reference material which is not marked with published year shall be applied by the latest document including all amendments and supplements (if any) TCVN 7572-1 to 20: 2006 Aggregate of mortar and concrete – Test method TCVN 4197:95 Construction soil - Method of determining the plastic limit and liquid limit in the laboratory TCVN 7572-12: 2006 Aggregate of concrete and mortar - Test methods - Part 12: Determination of wearability when impacted of big aggregate in Los Angeles Machine TCVN 7572-10: 2006 Aggregate of concrete and mortar - Test methods - Part 10: Determination of intensity and softening index of bedrock 22 TCN 332-06*) Pilot procedure to define CBR index of soil, rubble in the laboratory 22 TCN 346-06*) Pilot procedure to define density of road base and foundation by sand replacement method 22 TCN 211-06*) Flexible pavement design procedure 22 TCN 274-01*) Flexible road surface design standard 22TCN 333-06*) Process of soil and rubble compacting in laboratory TCVN 8864:2011 Road surface- Determination of flatness by 3-meters long meter TCVN 8818-1:2011 Liquid asphalt – Technical requirements – Part TCVN 8817-1:2011 Acids – asphalt emulsion-Technical requirements – Part Terminology, definition In this standard, the following terminologies and definitions are applied: 3.1 Graded Aggregate Is mixture of granular rocks of which the granularity complied with a continuous aggregate principle, denoted as CPĐD 3.2 Nominal maximum size of aggregate Is the size of the particle of which the largest conventional diameter of a graded aggregate, denoted as Dmax This nominal particle size is smaller than the diameter of the absolute largest particle size and the ratio of the particle which passes the sieve is respective with the nominal particle size of a graded aggregate accounts for 75-95% *) TCN standard should be changed in to TCVN standard Classification Graded aggregate used for road foundation is divided into 02 types: 4.1 Type I: is the graded aggregate of which all particle sizes are crushed from monolithic rock 4.2 Type II: is the graded aggregate crushed from monolithic rock or pebble gravel, in which a particle size smaller than 2.36mm can be nature un-crushed particle material but its quantity does not exceed 50% of graded aggregate quantity When grade aggregate is crushed from pebble gravel, 75% of the particle on 9.5mm sieve must have two or more surface of fracture Scope of usage of graded aggregates 5.1 Graded aggregate type I is used as base (and subbase in accordance with consideration of economic and technology) of pavement structure of which the surface layer is type A1, A2 according to 22TCN 221-06 or used as base according to 22TCN 274 – 01 5.2 Graded aggregate type II is used as subbase of pavement structure of which the surface layer is type A1 and used as base of which the surface layer is type A2 or B1 according to 22TCN 211 – 06 or used as subbase according to 22TCN 274 – 01 5.3 Both type I and II of graded aggregate can be used as subbase of hard road pavement structure (cement concrete) and graded aggregate type I can be used as base of cement concrete road pavement in case the road is used for only truck of below 80kN - cart load with the total running times until the end of the utilization duration is under 1x106 time equivalent to 80kN Technical requirements for graded aggregate 6.1 Requirement of type of rock All types of monolithic rock is used to crush and sieve to make graded aggregate must have the minimum compact strength of 60 Mpa if used as base and 40 MPa if used as subbase Crushed stone from sandstone and rocktex 6.2 Requirements of particle component of graded aggregate 6.2.1 Particle component of graded aggregate material is defined in Table Table – Particle component of graded aggregate Square sieve dimension, mm Percentage % of screened through sieve by weight Graded aggregate with nominal particle size D max = 37,5 mm 50 100 37,5 95 ÷ 100 25 Graded aggregate with nominal particle size D max = 25 mm Graded aggregate with nominal particle size D max = 19 mm 100 79 ÷ 90 100 19 58 ÷ 78 67 ÷ 83 90 ÷ 100 9,5 39 ÷ 59 49 ÷ 64 58 ÷ 73 4,75 24 ÷ 39 34 ÷ 54 39 ÷ 59 2,36 15 ÷ 30 25 ÷ 40 30 ÷ 45 0,425 ÷ 19 12 ÷ 24 13 ÷ 27 0,075 ÷ 12 ÷ 12 ÷ 12 6.2.2 The selection of graded aggregate type (in nominal particle size with maximum conventional diameter Dmax) must be based on the design thickness of foundation layer and must be specified in pavement structure design documents and technical instruction of the works: a) Graded aggregate with D max = 37, mm is suitable for subbase; b) Graded aggregate with D max = 25 mm is suitable for base; c) Graded aggregate with Dmax = 19 mm is suitable for leveling and strengthening on the old pavement structure in upgrading and improvement works 6.3 Requirements on physical and mechanical norms of graded aggregate material Physical and mechanical norms of graded aggregate material are defined in table Table – Physical and mechanical norms of graded aggregate material Norms Graded aggregate Test method Type I Type II Los-Angeles wearability of aggregate (LA), % ≤ 35 ≤ 40 TCVN 7572-12 : 2006 Bearing ratio (CBR) at K98 compact level, 96 hours water soaking, % ≥ 100 - 22TCN 332 06 Liquid limit (W L) 1), % ≤ 25 ≤ 35 TCVN 4197:1995 Plastic index (I P) 1), % ≤ ≤ TCVN 4197:1995 2) ≤ 45 ≤ 60 - Content of plat, diamond particle 3) ,% ≤ 18 ≤ 20 TCVN 7572 - 2006 Compaction density (K yc ), % ≥ 98 ≥ 98 22 TCN 333 06 Plasticity product PP (PP = Plastic index I P x % of amount passed through sieve 0,075 mm) (Method II-D) 1) Liquid limit, plastic limit are defined by the test of particle component passed through sieve 0,425 mm 2) PP is Plasticity Product in English 3) Flat, diamond particle is the particle of which the thickness or width is smaller or equal to 1/3 of the length; The test is carried out with the particle of which the dimension is bigger than 4.75mm and accounting for 5% of the sample.; Flat diamond particle content of sample is collected by the weighted average of the results was determined for each particle size 6.4 Sample 6.4.1 Sample of finished graded aggregate is taken at stock yard or at site to check the aggregate component after manufacture, required as follow: - Sample is requested to be taken from graded aggregate dune which was completely crushed, sieved and mixed; - Graded aggregate sample amount taken for material quality check is defined in table 3; - Flattening the surface, use shovel to take sample at 0.20m depth at least from the origin surface; - In parallel, sample is taken at 04 different positions on a grade aggregate dune, then mix them into a batch of required quantity and pack in box or bag to maintain and deliver to laboratory Table – Sample quantity Nominal biggest particle size, mm Material sample quantity, kg Graded aggregate with Dmax = 37,5 ≥ 200 Graded aggregate with Dmax = 25 ≥ 150 Graded aggregate with Dmax = 19 ≥ 100 6.4.2 Sample taking must be objectively Sample is maintained in wood box or plastic bowl or bag with label of “sample” 6.4.3 Before testing to analysis particle component, it is requested to pour out sample from box or bag, mix – up in 2min to 3min, then official sample will be taken for test Procedure is below: - Mix-up finely and divide that aggregate into 04 equal parts; - Take representative sample from that 04 equal parts follow the principle of equal for each part 6.4.4 The test sample taken must be the representative for the product batch or tested, checked section Depending on checking purposes and typical condition, sample can be taken in different methods and following the basic requirements below: a) When sample is taken at discharge gate, it should be ensured that all of discharged material is taken, nothing is dropped b) When sample is taken on conveyor belt, all material at a conveyor belt’s cross section must be collected, especially the fine aggregate; c) Material sample at discharge gate or on conveyor belt of a production line is not taken when the line just started due to instability; d) When sample is taken at stocked dune, for each dune, leveling the material at the top into a flat of no smaller than 50cm x 50cm dimension then digging in square hole to take enough material as regulated; e) When taking material on spread foundation layer, must dig as a vertical hole and take all material according to structure thickness 6.5 Test methods Test methods for each graded aggregate material indicator are specified in Table Construction requirements 7.1 Preparation for construction 7.1.1 Graded Aggregate Material Preparation a) Graded aggregate material source must be selected for the work This work includes investigation, testing and evaluation on the ability to meet the specifications and provide material under progress; b) Material from supply resource must be gathered at the storage at the construction site to conduct the material quality inspection and assessment - Material stock yard should be arranged close to the construction position and graded aggregate material must be stocked enough for at least a working shift; - Material stock yard must be reinforced in order to not be grubbed, mixed-up by transportation and construction vehicles and not to be flooded or not to be mixed with dirt or other materials ; - Materials from different source are not stocked in a same position; - In each delivery, stocking, a method should be prepared to avoid the graded aggregate material from layered (warm spray before scooping up, transporting) 7.1.2 Preparation of construction plan a) Conducting recovery, check of guide pile system of road center and road foundation’s edge; b) The construction of the graded aggregate bases are conducted only when the construction site has been acceptance When necessary, recheck the specifications of construction site, especially designed rolling tightness; c) For the construction site of the foundation or old pavement, detect and handle thoroughly the local damage position Damage repairs and warped compensation must be completed before construction of foundation When offset by graded aggregate, the minimum thickness of offset should be bigger than or equal to times of the nominal maximum particle size - Dmax 7.1.3 Preparation for primary construction equipment and equipment serve works a) Mobilize fully construction primary equipment as spreaders or graders, rollers, dump-cars transporting materials and humidity control equipment, elevation measuring machines and thickness control instruments , the equipment testing tightness and water content at site … b) Inspect all the basic features of primary construction equipment as spreading thickness control of the spreader, vibration system of vibratory, hydraulic control system of the grader blade ben, sprinkler system to ensure the ability to meet the technical specifications of graded aggregate material construction c) Putting the equipment on the production line in mass construction shall be based on the results of the pilot construction work (see 7.3) 7.2 Construction of the foundation by graded aggregate material 7.2.1 Graded aggregate material transported to the construction site construction shall be constructed immediately to avoid affecting to the quality and obstructing traffic 7.2.2 Requirements on the water content of the graded aggregate material a) The best humidity materials is in the optimum water content scope (W o ± 2%) should be maintained during transportation, gathering, or spreading and rolling b) Before and during construction, shall be checked and adjusted humidity of materials timely - If the material has a lower moisture than optimum moisture, must be supplemented by water sprinklers and not let water runoff fine particles The additional moisture should be incorporated in the spreading process and rolling with attached mist spray; - If the humidity is greater than the optimum moisture, must spread out to dry before rolling 7.2.3 The spreading work a) For the super-base, the graded aggregate material is spreading by spreader b) For the sub-base, use the spreader to improve the quality of work Only using graders to spread material when have fully measures against segregation of graded aggregate materials and approved by Consultant When using graders, the graded aggregate were poured into the pile on the work site with the proper gap determined through pilot construction specified in Section 7.3 but the gap is not greater than 10m c) Base on the features of the device, the design thickness, can split into construction layer The thickness of each construction layer after rolling is not greater than 15cm Special cases may require higher thickness, must use modern roller and special scheme, but shall not exceed 18cm in any case d) To decide the thickness of spreading (through the rolling coefficient), must base on the pilot test results, determining preliminary spreading coefficient (rolling coefficient) K spreading as follows: [1] In which: is the greatest dry volume weight under pilot results of compaction standards, g/cm3; the dry volume weight of the graded aggregate material in the state (no compaction), g/cm3; Kyc is required tightness of graded aggregate class, % e) To ensure rolling tightness across the entire width of the foundation, without mold or rock strata, it need spreading additional material each minimum width of 25 cm compared to the design width of the foundation At the adjacent position to the prior spreading trail, remove the loose material at the edge of prior trail before spreading the next trail f) In case of using the grader for spreading graded aggregate material, allocate skilled workers driving machine and workers supporting machine in order to limit and handle the material segregation The position on which material is segregated is needed removing the entire material and replace with new material The establishment of operation scheme of grader and spreader base on the results of the pilot construction work (see 7.3) g) Must regularly check the elevation, the flatness, horizontal slope, vertical slope, humidity, homogeneity of graded aggregate materials during spreading 7.2.4 The rolling work a) Select and combine rollers in the rolling scheme depending on the type of stone used as material, thickness, width and vertical slope of the foundation Typically, use light roller 60-80 kN with slow velocity km/h to roll from to first turn, then using vibratory rollers 100-120 kN or roller with wheel load 25 - 40 kN to roll from 12 to 20 times until it reaches the required tightness, and finished with 2-3 turns of heavy steel roller 80-100 kN b) The number of rolling to ensure uniform for all points on the surface of the nail (including extensions), and to ensure flatness after rolling c) Rolling be done from low place to high place, the superposition of rolling wheel tracks is 20 cm at least The straight road is rolled from the edge to the center line and in curve segments, rolled from the abdominal road to the back curve road d) After preliminary rolling, immediately inspection for elevation, horizontal slope, flatness and found the uneven or segregated position to repair and have cascade compensation timely: - If notice unusual phenomena such as cracks, ripples, put buckets or loose, stop rolling to find the cause and thoroughly treat before continuing All work must be completed before reaching the 80% rolling work; - If must have cascade compensate after completed rolling, the surface foundation must be plowed with a minimum depth of 5cm before cascade compensation e) Rolling technology scheme applied to the mass construction for each used material layer as rolling order, the number of rolling must be built on the basis of pilot graded aggregate base construction (stipulated in 7.3) 7.2.5 Maintenance and tack coat application a) To prevent fine particles blown away, it is necessary to regularly keep enough moisture for the surface foundation of aggregate base course In addition, not let vehicles transport on the foundation before tack coat spraying to avoid chipping b) For the subbase, it is necessary to quickly spray tack coat by MC-70 (in accordance with ISO Standard 8818-1: 2011) or asphalt emulsion type SS-1h or CSS-1h (accordance with ISO standard 8817-1: 2011) - Before spraying tack coat, foundation surface should be cleaned to remove dust, garbage and discrete materials by using appropriate tools such as brushes, compressors without making foundation aggregate chipped; - When applying the tack coat, the air temperature must be higher than oC, and the temperature of the tack coat must be ensure properly at 70o C - 10o C for liquid asphalt MC70; - The tack coat is sprayed evenly on the whole foundation surface by specialized equipment with injection pressure from 0,2 MPa to 0,5 MPa and and the norm is 1,2 l/m ± 0,1 l/m for liquid asphalt MC70 or 1,8 l/ m for emulsion SS1h and CSS-1h c) If traffic must be ensured smoothly, a layer of grit of 0.5 cm x 0.1cm size should be used to cover the tack coat right after spraying and lightly roll about 2-3 times/point At the same time, daily maintain should be arranged for surface water drainage, additional compensation, drift stone remove and re-roll where chipped by vehicle transportation 7.3 Pilot construction 7.3.1 Requirement of pilot construction work a) Pilot construction work shall be applied for each work as following cases: - Before mass construction implementation; - When changes appear on official work equipment: heavy roller, grader, and spreader; - When changes appear on material supply resource or types of graded aggregate material b) Pilot construction work is basis to propose mass construction measures to ensure following to technical, quality and economy requirements Therefore, pilot construction have to provide the optimal technological parameters follows: - Map of material gathering, operating scheme of the grader or spreader; - Select the appropriate rollers with stones used as graded aggregate materials; - Rolling coefficient, the optimum thickness of the construction layer; - Rolling scheme of each type of roller with the order and rolling process, velocity and the number of rolling times over a point; - The auxiliary work such as cascade compensation, segregation treatment and processing checks, inspection the quality and construction progress c) The entire pilot construction work from set plan to establish technology line applying for mass construction shall be checked and approved by Consultant 7.3.2 Establishment of pilot method statement a) The sections are selected for pilot construction must present for construction area of each construction unit of: structure type of construction plan, longitudinal slope, cross slope, width of subgrade…Typically, the minimum length of each pilot segment is 50m; b) Base on the construction schedule requirements, material provision schedule requirements, actual condition of construction plan, mobilization ability of construction equipment and other requirements mentioned in item 7.3.1, at least 02 technical diagram for pilot construction should be made for 02 pilot construction segments selected; c) When technical diagram for pilot construction is prepared, all technologies of available construction equipment must be considered, combine with construction experience has been accumulated and actual conditions of equipment capacity and actual site In technical diagram for pilot construction, the followings must be specified: According to the instruction in 7.2.3, the preliminary thickness of each graded aggregate material layers after spreading or grading shall be specified (at the beginning, compaction ratio can temporarily be 1.3); Select and mobilize the proper roller type; Prepare rolling map for each roller type, in which specifying the order of rolling, frequency and speed for each positions, the coordination of roller types… Preliminary establishment of additional tasks, the steps and the time of inspection, monitoring should take to ensure the smooth operation of the construction line and project quality assurance 7.3.3 Pilot construction implementation a) Pilot construction implementation according to the technological scheme was set up on the various pilot segments From the results of the pilot construction, need to record basic data of each implemented construction step as below: - Weight of material transported to site The distance between the spreader and graded aggregate piles when the sub-base are allowed to be constructed by grader; - Additional water measures to ensure moisture during and after leveling or spreading; - Elevation before and after leveling or spreading graded aggregate material; - Select the type of light and heavy roller for the construction; - Identify the number of preliminary rolling by light roller and compaction by heavy rollers corresponds to the rollers are mobilized at site; - Handling the segregating phenomenon, wavy, poor flat and need to cascade compensate (if any); - The order of rollers in and out, number of turns and velocity of roller through a point; - The experimental results determined tightness, construction moisture (at the end of the rolling process) to correspond the number of passing times of each types of rollers at acceptance position; - Elevation after completion of the rolling work for graded aggregate bases; - Start and finish time, weather conditions when carrying out pilot b) From the collected data, calculating and adjusting the parameters as: - Spreading ratio (compact ratio) K-spreading is determined based on the elevation data on the same section at the corresponding points as follows: [2] In which: CĐmb is elevation of construction surface, m; CĐrải is elevation of graded aggregate base surface after spreading , m; CĐlu is elevation of graded aggregate base surface after rolling, (meet the required tightness) m - The correlation between the number of rolling (or rollers) and achieved tightness; - The number of vehicles involved in the line, the distance between piles (if spreading by graders) c) Adjust pilot construction scheme to apply for mass construction Request for inspection and acceptance 8.1 Sampling materials of graded aggregate base for the acceptance testing of material quality 8.1.1 To serve the quality control of materials during construction at the site and acceptance, the minimum volume requirements of samples are taken at the site in accordance with the provisions in Table 8.1.2 Sampling taken at the construction site must represent the product or tested segment The sampling can be implemented according to the different methods and comply with the provisions of 6.3 8.2 Inspection and acceptance of material quality The inspection and acceptance for material quality must be conducted in the following stages: 8.2.1 Duration of checking serves the approve for the supply resource of graded aggregate base materials for construction a) Sample is taken at source; 3000 m3 of material supplied for works or related to one of the following cases, it shall take a sample at least: - Material source provided for the project for the first time; - A change of exploitation strata of monolithic rock; - A change of lines of crushing and sieving or crushing jaw or sieve size; - There is an extraordinary quality of materials b) Materials shall meet all physical and mechanical conditions specified in Table and Table 8.2.2 Duration of checking serves the acceptance of material quality gathered at site compound to use - Sample is taken at the storage at the site, every 1,000 m3 of material, must take one sample at least for each supply resource or when there is an abnormality of material quality; - Material must meet all of the physical and mechanical provisions in Table and Table prior to test compressive tightness in the laboratory 8.3 Inspection during construction During the construction process, the construction unit shall regularly conduct experiments, checks according to the following: 8.3.1 Water content, stratification of material (visual inspection and particle composition test) For every 200 m3 of material or a construction shift, it shall be to conduct to test particle composition and moisture content on a sample 8.3.2 Tightness of rolling - The tests carried out according to 22 BC 346-06 and conducted at each graded aggregate base had been accomplished; - By the end stage of the process rolling, must regularly check rolling tightness as a basis to complete the rolling process For every 800 m2, conducting tests to determine the rolling tightness in a random location 8.3.3 The geometric elements, flatness - Elevation, slope of horizontal surface foundation is the base determined on the data of elevation measure at center light and the edge of the base; - Thickness of the foundation is the base determined on the data of elevation measurements before and after construction at the respective point on the same section (if necessary, conduct pitting for checking.); - Foundation width is determined by the steel meter; - The flat was measured by a 3m-meter in accordance with ISO 8864: 2011 The largest openings under meter is specified in Table 4; - Density check and requirements in detail specified in Table Table Requirements on the geometric dimensions and the flatness of the base with graded aggregate Checked Indicator Permitted Limit Sub-base Base Elevation - 10 mm - mm Horizontal slope ± 0,5 % ± 0,3 % Thickness ± 10 mm ± mm Checking Density Every 40m to 50m with line sections, 20m to 25m with curved sections measured by a across section 4 Width - 50 mm - 50 mm The flatness: the largest gap under meter 3m ≤ 10 mm ≤ mm Measure at positions of every 100m 8.4 Inspection after construction to serve the acceptance of work items - Check the tightness and particle composition inspection after rolling and the thickness of the foundation: 7000 m or km length (2-lane road) need test checking by the methods of pitting pouring sand at two random locations (particularly in the case of spreading by graders shall check at three random locations) - Check the geometry and flatness: shall conducted to check with the measure density of only 20% of the volume specified in Table 4, the equivalent of measure density as follows: - Measure to check geometric elements (elevation of center light, the edge of foundation, foundation width and across slope): 250m/position on the line and 100 m/location of the curve Measure to check the surface flatness by 3m-meter: 500 m/location Provisions on labor safety and environmental protection 9.1 General provisions for the selection, processing, fabrication of the mixed graded aggregate bases and construction of sub base-pavement to ensure compliance with the current regulations of hygiene, labor safety (LS) Requirements of labor safety checks on people, equipment and the site before the construction 9.2 Must have measures to ensure traffic safety during preparation, material storage and construction 9.3 When constructing graded aggregate bases, watering regularly is needed to ensure that dust levels not exceed the permitted values as currently stipulated and compliance with the Law on Environmental Protection ... (if any) TCVN 7572-1 to 20: 2006 Aggregate of mortar and concrete – Test method TCVN 4197:95 Construction soil - Method of determining the plastic limit and liquid limit in the laboratory TCVN 7572-12:... compacting in laboratory TCVN 8864:2011 Road surface- Determination of flatness by 3-meters long meter TCVN 8818-1:2011 Liquid asphalt – Technical requirements – Part TCVN 8817-1:2011 Acids –... 40 TCVN 7572-12 : 2006 Bearing ratio (CBR) at K98 compact level, 96 hours water soaking, % ≥ 100 - 22TCN 332 06 Liquid limit (W L) 1), % ≤ 25 ≤ 35 TCVN 4197:1995 Plastic index (I P) 1), % ≤ ≤ TCVN