Quality control in road and highway construction is used for obtaining an improved and uniform standard of road construction. Quality control of construction materials and the product is an essential requirement.
Quality control is an essential part of any production process and Quality control in road and highway construction is no exception. Due to significant increases in traffic intensities in recent times, the need for quality control on these specifications has increased considerably. Improving the level of service of roads and highways results in considerable savings in operating costs of vehicles and in favorable road user reactions and opinions of the public.
The extra cost of exercising quality control is only a minute cost i.e 1-2 percent of the total construction cost and hence result in more benefits. And direct and indirect economic returns from quality control could be 5 to 10 of the total construction cost.
Table of Contents
Requirement of Road Construction Quality Control
Mainly road construction estimates and specifications provide the basis for effective quality control. Plus organizations set up quality management systems, adequately trained staff, and proper monitoring agencies for exercising quality control.
For effecting possible improvements and implementation in quality control and the construction techniques the periodic appraisal of quality control data is necessary.
Quality Control Types in Road Construction
1. Process Quality control
The designer makes decisions regarding the type of procedure of construction, equipment, and the amount of work required to obtain the desired result.
2. End Quality Control
In the end result of Quality control in Road and Highway Construction, the construction agency maybe a contractor, have a free hand in the selection of road construction methods and equipment to achieve the desired end product. In End result type specification, the quality engineer carries out tests on finished work at regular intervals to evaluate whether it meets the required specifications or not.
3. Frequency & Extent of Site Testing
The frequency and extent of testing for normal conditions are the minimum necessary consideration. And for abnormal conditions where excessive variations are found to carry out additional testing.
4. Criteria for Site Acceptance
For different items of work, acceptance criteria may be based on minimum values or the statistical analysis as it is considered wise. For effective road construction quality control of material and work, it will usually be necessary to lay down the acceptance criteria in contract documents.
| Test | Test Method | Minimum Frequency |
| Los-Angeles Abrasion value/Aggregate impact value | IS:2368 (Part 4-1963) | One test per 50-100 m3 Of aggregate |
| Quality of binder | IS:73-1961 | As required |
| Stripping value of Aggregate | IS:6241-1971 | Do |
| Water Absorption of Aggregate | IS:2386 (Part3-1963) | Do` |
| Flakiness index of Aggregate | IS:2386 (Part 1 – 1963) | Do |
| Sieve Analysis of Filler | Do | One Test per 5m3 of filler |
| Mix Grading | IS:2386 | For Every 100 tonnes of mix |
Training on Quality Control:
To bring awareness to the officers of the department and to update their knowledge of methods of testing, a regular workshop on quality control should be held.
In order to make awareness in participants of basic necessities like required test acceptance criteria, specifications, frequency of testing, and methodology of tests for understanding the quality control system and operation of regional and field laboratories.
Project Site training Facilities:
There are central, regional, and field-level testing facilities normally. The Regional labs are at circle level and headed by Quality Engineer
In addition, they shall provide all facilities for training of all Quality Control Staff in the region.
Critical Parameters in Quality Control for Road Construction:
The following points for construction in-process quality control shall be attended to
- The mix design proportions arrived in the lab shall be based on representative samples of material actually available at the site.
- Combined aggregate gradation and binder content shall satisfy the design criteria of the relevant IRC specifications.
- At necessary places apply a prime coat over the prepared base at the specified rate before laying the bitumen surface
- The adequate capacity of mixing plant to field a mixture of proper and uniform quality.
- Quantities of various sizes of aggregate shall be fed in such proportions that the resulting combination follows the job-mix formula.
- To obtain a uniform distribution of the binder and the homogenous mix mixing time is should be the shortest possible.
- A variation of +0.3 % in binder content by weight of the total mix shall be permissible.
- The tipper truck carried the mix to the site and spread and compacted to obtain a carpet of the required thickness. Self-propelled mechanical pavers do spreading provided with screeds for spreading tamping and finishing the mix True to grade, cross-section, and line.
- Quickly after laying the mix, rolling shall be started with 8-10 tonnes vibratory rollers at the speed, not more than 5 km/hr. the final rolling shall continue till the mix is fully compacted and on the surface, there are no roller marks are left. The density of the mix is not less than 90 percent of the laboratory density. During rolling the roller wheel should be kept moist to prevent the mix from adhering to the roller wheels and being picked up.
- Traffic is allowed only when the carpet after final rolling has cool down to ambient temperature.
- The finished surface shall be checked in-process quality control for line, regularity, and grade.
Concrete Pavement Quality Control:
- As per guidelines given in IRC: 15-2002 the construction of pavement shall follow this.
- Standard specifications and code of practice for construction of concrete roads
- For tools, equipment, and appliances contractor should follow IRC:43-1972.
Mix proportions for concrete shall be pre-determined on basis of strength as per guidelines given in IRC:59-1976 and IRC:44-1972.
Quality control test on the material
| Cement | Physical and chemical tests | IS:269-1967 |
| Coarse and Fine Aggregates | Gradation Moisture content Fine Aggregate | IS:2386( IS:2386 Part 3 1963 IS:2386 part 2 1963 |
| Coarse Aggregate | Soundness Los Angeles, Abrasion value/ Aggregate impact value test, Alkali Aggregate reactivity | IS:2386 part 4, 1963 IS:2386Part 4,1963 IS:2386Part 5 1963 |
| Water | Chemical Activity | IS:425-1964 |