Road construction manual

Traveler information. Construction Checklists Documentation Manual. Portal Local Projects. Step 1 Step 2 Step 3 Step 4 Sample Riffling:- the process of obtaining a small representative quantity of sample by dividing a large quantity of material using a riffle box or sample splitter containing alternating slots , which divide the material into two equal parts.

Then, one of the obtained two parts is poured again into the slots until the desired quantity is obtained. Test procedure: a Dry Sieving: 1 Obtain a test sample by quartering or riffling the material. Grading Sieves 6 Weigh either individually or cumulatively the material retained on each sieve m2. Note: Cumulative weights provide the percentage of particles retained on the sieves progressively, while individual weights provide the percentage retained on an individual sieve does not follow the sieve sequence.

The indices obtained in both tests reveal the dimensions of aggregate particles, as some particles are normally cubic while others are flaky or elongated. The test is carried out on the aggregate particles of different sizes from 6. Flaky particles Test procedure: 1 Obtain the test sample by quartering or riffling the aggregate. Retained Wt. Passing fraction fraction on the gauge on the gauge mm g g g 63 - 50 It is carried out on the coarse particles from 6.

Test procedure: 1 Obtain the test sample by quartering or riffling the aggregate. Passing on fraction fraction on the gauge the gauge mm g g g 50 - Aggregate Crushing Value ACV Some aggregate particles resist crushing while some crush during rolling due to the effect of weathering process or micro-fractures developed by blasting or crushing operations.

Crushing of aggregates during construction process affects the grading, density and strength of a mix or layer made with such aggregate.

To measure resistance of aggregate to crushing, the ACV test is carried out on the 14 — 10mm aggregate fraction, by applying a KN force gradually over a period of 10 minutes. Test procedure: 1 Obtain the required fraction by sieving the aggregate on 14mm and 10mm sieves. Rock fissures 2 Take the fraction passing 14mm but retaining on 10mm sieve and dry it in oven for about 4 hours before testing. Retained on 2. Passing 2. It is also conducted on the 14 — 10mm fraction as for the ACV test, however, the TFV is preferred for weak aggregates in order to overcome the cushioning effect of excessive fines that might be produced by the ACV test.

The test is carried out on a dry or soaked aggregate sample. Test procedure: 1 Sieve the aggregate on 14mm and 10mm sieves as for the ACV.

Compression Machine 2 Plot the results on a chart with forces on x-axis and the percentage passing 2. It is commonly carried out on the 14 — 10mm fraction; however, 20 — 14mm or 10 — 6. The chosen fraction can be tested in a dry condition or soaked condition. Test procedure: 1 Obtain the required fraction by sieving aggregate on the specified sieves e.

Retained on the sieve m2 Passing separation sieve p The applicable aggregate fractions are: Group A: Mix Group B: Mix 19 — Group C: Mix 9. Group D: Take 4. LAA Machine 2 Obtain about g from each group i. Calculations: Material passing 1.

Sulphate Soundness SS Sulphate soundness test measures the effect of salts on aggregate particles. The effect is measured as the loss in aggregate weight after repetitive drying and soaking the aggregate in Sodium or Magnesium sulphate solution. The applicable sulphate solution is prepared as follows; Sodium sulphate solution: is made up of g of Sodium sulphate and 1 litre of water is supposed to have a specific gravity of 1. Magnesium sulphate solution: is made up of g of Magnesium sulphate and 1 litre of water is supposed to have a specific Sound aggregate gravity of 1.

Test procedure: 1 Obtain the sample by quartering or riffling a large quantity of aggregate. Repeat soaking and drying five times cycles. Unsound aggregate 11 After the 5th cycle of soaking and drying , allow the samples to cool and wash them thoroughly with warm water at 45 0 C. Organic Impurities Presence of organic impurities in aggregates especially natural sand affects the setting time and hardening of concrete and may also cause deterioration of concrete or pop-outs.

To test the organic impurities in fine aggregate, the following stuff is used: Test reagent: a solution made up of 3-parts Sodium hydroxide NaOH and parts water. Standard solution: a solution made up of 0. It is used as a reference colour for classifying the sample solution after adding the reagent.

Colour plate: a small plastic plate with different colour slots, used to Sodium hydroxide classify the colour of sample solution as a substitute for the standard solution. Test procedure: 1 Obtain a test sample of about g by quartering or riffling a large quantity of fine aggregate sand. Lime 6 Allow the sample to stand undisturbed for 24 hours and compare the colour of the sample solution with the colours on the colour plate or with the standard solution.

Clay lumps and friable particles Clay lumps are small soil balls, which visually look-like gravel or aggregate particles, but soften and dissolve in water or liquids. Friable particles are granular particles which lose bond and break up crumble in water or liquids.

Presence of the dissolving or crumbling particles in an aggregate group affects density, strength and durability of a mix made with the aggregate.

As such weak particles crumble during rolling or disintegrate due to moisture; they leave pockets and form weak planes in a concrete structure or pavement layer. To test such defective particles, the aggregate fractions are soaked in water and squeezed by fingers to dissolve or break up the lumps Typical friable particles and friable particles.

Test procedure: 1 Divide aggregate by quartering or riffling to obtain test sample. Material finer than 0. On the other hand, such finer materials increase water demand for a concrete mix, resulting into a low strength concrete. To test presence of such deleterious materials, aggregate fraction is immersed in water to disperse the finer materials and decanted on the 0. Then, the loss in weight obtained after decantation is counted as the amount of materials finer than 0.

The applicable terms in the test include the following; Decantation: removal of suspended materials by tilting a container Variety of aggregate particles gently without disturbing the settled particles.

Suspensoid: a solution of very fine particles dispersed throughout a liquid. Test procedure: 1 Divide aggregate by riffling or quartering to obtain the sample. Repeat this step until water is free of suspensoid. Calculations: Material finer than 0. Lightweight pieces Presence of porous and light pieces e. To measure the presence of suchlike pieces, aggregate particles are immersed in a heavy liquid with higher specific gravity than water and floating materials decanted and weighed as the lightweight pieces.

Heavy liquid may be made by dissolving the following compounds in water: o Zinc Chloride for SG less than 2. Recommended weight of sample Test procedure: for Coal and lignite test: 1 Divide the aggregate to obtain the representative test sample. Acid-soluble materials Presence of acid-soluble materials in the aggregate mass may affect durability of the aggregates and structures exposed to a chemical environment.

In testing the acid-soluble materials, aggregate particles are soaked in diluted hydrochloric acid solution and percentage loss in aggregate weight is calculated and reported as the quantity of acid-soluble materials. Test procedure: 1 Dilute ml of concentrated hydrochloric acid with relative density of 1. Specific gravity SG Specific gravity is the ratio of density of a solid particle to the density of distilled water.

In addition, the test measures impermeability of aggregate particles water absorption. It is a useful data for computing the volume of aggregate and voids in different mixes especially concrete and asphalt. Generally, the three parameters given by the test are: Bulk specific gravity:- the density of permeable particle including permeable and impermeable voids normal to the particle.

Apparent specific gravity:- the density of impermeable portion of particle excluding permeable and impermeable voids normal to the particle. Water absorption:- the amount of water absorbed by solid particle expressed as percentage of dry mass of the particle. Glass Pycnometer Test procedure: a Fine aggregate passing 4. Cone and Tamping rod 9 Add more water and shake pycnometer to remove air bubbles.

Sand equivalent SE Sand equivalent test determines the proportion of plastic clays, silts or amount of dust in fine aggregates for concrete. To conduct the test, a working solution of Calcium chloride is used to disperse clay and dust into suspension; and the height of sand column sand reading is measured and compared to the height of suspension clay reading.

The test includes the following terms; Working solution:- is made up of 22ml of stock Calcium chloride solution to 1 litre of water. Sand reading:- top level of sand column. Sand Equivalent test set Clay reading:- top level of clay suspension. Test procedure: 1 Fill a graduated cylinder with ml of working solution. Sand Reading h2 7 Then, twist the irrigator in the material to flash the fine materials into suspension until the cylinder is filled to the calibration mark.

Cement According to BS 12, cement is hydraulic binder finely ground inorganic material , which when mixed with water forms a paste that sets and hardens by means of hydration reactions and processes; and which after hardening retains its strength and stability even under water.

Clinker is again ground down into a finer powder smaller than 0. When mixed with water, cement forms a paste that sets and hardens by means of hydration process chemical reaction between cement compounds and water molecules, which generate heat known as heat of hydration.

Evaluations of cement properties require sophisticated laboratory equipment and skills. However, since cement is manufactured under controlled process, most of the tests are conducted at the factory laboratory and supplied with cement batches as quality V1 document certificate of quality. Therefore, very few tests are normally conducted at the site laboratory. Test Procedure: 1 Fill a small-calibrated measuring cylinder with reasonable volume of kerosene V1.

Test Procedure: 1 Mix g of cement with a measured quantity of water to produce a plastic mouldable paste. Record that percentage as the moisture content for normal consistency.

Aggregate Aggregate is used in concrete to expand the mix volume, to control shrinkage properties and to contribute strength. As a result, quality of aggregate has great influence on the strength, workability, permeability and durability of concrete mixes.

Concrete aggregate should be clean and strong enough to resist forces and exposure conditions. The particles should be hard, dense and free from excess dust. Soft aggregates e. Therefore, careful selection of rock source is very Crushed Aggregate important, as quality of aggregates depends on the geological composition of the rock. However some researchers recommend the use of marine aggregates for concrete after washing with clean water due to concentration of salts sulphate and chloride , the suitability of such material should be carefully investigated and proved by laboratory testing if washing has significantly reduced the injurious substances to an acceptable amount.

Table 4. Smooth and rounded particles produce better workability but develop weak internal friction and poor bond with cement paste. Flaky and elongated particles produce poor workability and particle interlock.

Therefore, aggregate particles should be cubic, rough and well graded from fine to coarse to enable workability, proper bond Coral Aggregate soft and adequate density. Water Water to be used for concrete should be clean and free from aggressive compounds such as; oil, acid, alkali, salt, sugar, organic matter and other compounds that may attack concrete components.

Such injurious substances may affect the setting time, strength, bond and shrinkage of concrete; or may cause corrosion of reinforcements. Generally, drinking water is the mostly recommended water for concrete production and curing. It looks like your browser does not have JavaScript enabled. Please turn on JavaScript and try again. Construction Manual. NC Department of Transportation. Click Here. This manual was developed to provide a more user-friendly, interactive and searchable format for our users.

If a conflict arises between the Standard Specifications for Roads and Structures or contract documents and this manual, the specifications and contract documents will have precedence. As specifications, practices, procedures, and policies change, the Division of Construction will issue updated Construction Manual sections.

The dates in the right-hand column of the list of sections reflect the publication date of the most recent revision. MCTs provide a summary of manual changes followed by the updated section with lines in the margin to indicate changes. When MCTs are issued, the updated sections will be added to the Construction Manual full download as soon as possible. Section footer dates are also changed to match the month the MCT was issued.

Construction Procedure Directive CPD memorandums also are issued to clarify information already contained in the manual, introduce a process change, remind readers of existing policy, announce a new form, or inform the reader of a change in address or contact.