TRF - 2010
http://dl.lib.uom.lk/handle/123/17947
2024-03-29T05:10:30ZTransport Research Forum 2010 (Pre Text)
http://dl.lib.uom.lk/handle/123/20318
Transport Research Forum 2010 (Pre Text)
Pasindu, HR
2010-01-01T00:00:00ZDetermination of an effective laying pattern and best block shape for concrete block pavement based on field performance
http://dl.lib.uom.lk/handle/123/18282
Determination of an effective laying pattern and best block shape for concrete block pavement based on field performance
Senadeera, AA; Mampearachchi, WK
Pasindu, HR
There has been an intensive process of urbanization which has brought about need for rapid construction of roads and related infrastructure during the end of the last century. Therefore development of economical road construction methods is a high priority for a developing country like Sri Lanka. Concrete block paving is one of the predominant road construction method used in most of the developing counties due to economic adaptability and this has emerged as a cost effective road construction method suitable for certain local conditions. But in Sri Lanka this technique is yet to be developed to a fully fledge road construction method. This can be attributed to a dearth of the technical expertise and knowledge. As a result, there is a great need to develop knowledge and establish proper methods of block paving.
The performance of concrete block pavements vary with block shape, thickness, size of the block, compressive strength ,laying pattern, bedding sand and sub grade conditions. Therefore, considerable amount of research has been done recently with Concrete Block Pavement models in order to analysis their performance with respect to various factors. But most of the researches on CBP have been done in laboratory models and very low traffic roads and these tests may not simulate real situation. This research will cover the real ground situation and the behavior and the effects of blocks due to traffic weights.
Objective
1 determine most suitable individual block shape for CBP roads
2 determine effective laying pattern for CBP roads
Method/design
This research was covered the real ground situation and the behavior and the effects of blocks due to traffic weights with high percentage of heavy truck and buses.. Under this study, concrete blocks were cast according to the specifications in predetermined shapes and paving was done with different block shapes and patterns in a road which contains vehicular traffic.
Selected 100m road length was divided to 10 equal parts and blocks were paved according to selected pattern and block shapes in each different section.
Deflection was measured by using Benkelman instrument and block displacement were measured by using venire caliper. The most effective block shape and pattern were selected comparing deflection and block displacement in each combination of block shape and patterns.
Findings
The analysis of results show that the following results
Most effective block shape is Uni style
Most effective block paving patterns are Stretcher and Herring. Both show similarly good results.
The effective laying angles are 0 and 90 degrees. Here again both angles show good results.
Conclusions
Under this study, concrete block paving road was constructed. Concrete blocks were cast according to the specifications in predetermined shapes and paving was done with different block shapes and patterns. Then the performances of the block paving were observed after allowing traffic. The data were collected to determine the most effective block shape and pattern.
The most effective combination of variables for cement concrete block laying are Uni style block shape, Stretcher and Herring block pattern and zero or 90 degree block angle can be recommended for new CBP roads.
2010-01-01T00:00:00ZEconomical mix design for interlocking block paving for Sri Lanka
http://dl.lib.uom.lk/handle/123/18281
Economical mix design for interlocking block paving for Sri Lanka
Pilanavithana, US; Perera, PS; Appuhami, RSBR; Mampearachchi, WK
Pasindu, HR
Rocketed trend of world wide Concrete Block Paving (CBP) adherence to the road network has already influenced the Sri Lanka as a well performing alternative for the rigid concrete pavements which caused many issues over past decades. Even though CBP in larger Production level, significant Standards and Guidelines for basic properties and manufacturing in the Sri Lankan conditions have not been introduced yet. Especially in application of CBP in trafficked road ways seems to be declined as it is not deeply concerned by the authorities due to lack of guidance. In that case the requirement of study in concrete mix design of CBP for roads phenomena was come across.
In an attempt to find the a economical mix design for concrete block paving optimized combination of cementitious and aggregate materials has been developed, which contains cement, sand, quarry dust and chips in intended for the production of interlocked concrete blocks for paving in road pavement. The main purpose was to achieve optimized Concrete Blocks with fulfilling the requirements in road by using alternative aggregates, admixtures and the production cost via materials.
The initial mix design was developed with the use of literature review and besides that other mix proportions were introduced by altering the initial design. First series of blocks were produced by using above mix designs by varying the aggregate-cement ratio (A/C) and water-cement ratio (W/C) between 0.25 – 0.40. Optimized value was selected considering the Compressive strength, Surface texture and Shape (edges). Next series was casted from the selected mix design and sand was replaced by quarry dust in proportion to the total fine aggregate weight. Final mix design was developed with those results and it showed significant high energy requirement compared to the first series.
Seven days Compressive strength of CBP with out quarry dust was varied between 52 N/mm2 – 34 N/mm2 with in the W/C of 0.25-0.40. It was given 41 N/mm2 – 46 N/mm2 variations for the W/C of 0.30 after replacing the quarry dust with sand. This has satisfied the required strength of 35 N/mm2 for the commercial vehicles. All mix designs produced zero slumps. Compressive Strength has correlations with the A/C, W/C, Density and Sand Percentage. W/C inversely affects the shape and texture.
In conclusion, Sand can be replaced by quarry dust as a successful alternative aggregate with a unique proportion. W/C ratio plays major role while restricting to upper limit to fulfill surface texture and shape. Quarry dust improves strength with a unique proportion of sand while acquiring more energy in production.
2010-01-01T00:00:00ZFinite element model analysis to determine improved support condition for concrete block paved low volume roads
http://dl.lib.uom.lk/handle/123/18280
Finite element model analysis to determine improved support condition for concrete block paved low volume roads
Gunarathna, WPH; Mampearachchi, WK
Pasindu, HR
The intensive process of urbanization in the last century has caused a need for rapid construction of roads and related infrastructure in Sri Lanka. The rapid demand for better roads and services required the designers and the builders to introduce suitable construction methods in order to economize the construction as well as increase the durability. In Sri Lanka, large percentage of low volume roads has been constructed using gravel, concrete or bitumen as the primary material. Due to lack of maintenance of the roads in rural sector, Engineers are trying to find alternative cost effective pavement construction techniques.
Concrete block paving (CBP) is one of the predominant road construction methods used in most of the developing counties due to economic adaptability. This method can be emerged as a cost effective road construction method suitable for different ground conditions with low life cycle cost. However, this technique yet to be developed to a fully fledge road construction method in Sri Lanka. Therefore, standard set of guide lines are needed to maintain consistency and construction quality of block paving technology.
The aim of this research is to evaluate the state of support conditions for low volume roads and effective block laying patterns which can be used to obtained best performance from concrete block paving. Therefore verified three-dimensional (3-D) finite element model (using SAP2000 structural analysis software) was used to measure elastic deflection behavior of concrete block pavement for low volume roads. Developed design chart can be used for subgrade improvements for low volume roads condition and find best laying arrangement in the concrete block paving to obtain most excellent interlocking action.
2010-01-01T00:00:00Z