Tremix concrete Tentative Design and Estimate
Sample calculations for the design of a Tremix concrete road as per Indian standards for Estimate Purpose:
1. Subgrade Preparation:
Assuming the subgrade is compacted to a density of 95%, the sub-base layer thickness of 100 mm, and a granular material with a bulk density of 1,600 kg/m³, the weight of the sub-base material required per unit area (1 m²) can be calculated as follows:
Weight of sub-base material = Thickness x Bulk density x Density of subgrade
= 0.1 m x 1,600 kg/m³ x 0.95 = 152 kg/m²
2. Concrete Mix Design: Assuming a target compressive strength of 30 MPa and a maximum aggregate size of 20 mm, the mix design for 1 m³ of concrete can be calculated as follows:
Water-cement ratio = 0.45
Cement content = 350 kg/m³
Water content = Water-cement ratio x Cement content
= 0.45 x 350 = 157.5 kg/m³
Fine aggregate content = 0.5 x (1 - Water-cement ratio) x Cement content / Bulk density of fine aggregate
= 0.5 x (1 - 0.45) x 350 / 1,600
= 73.4375 kg/m³
Coarse aggregate content = Cement content + Fine aggregate content + Water content - Air content - Admixture content
= 350 + 73.4375 + 157.5 - 2.0 - 0.0
= 579.9375 kg/m³
3. Here are the sampledesign calculations for constructing a Tremix concrete road of M30 grade using 100 mm WMM and 150 mm M10 grade concrete for a traffic of 450 PCU (Passenger Car Units) for Estimate Preparation purpose:
Design parameters:
Design life: 15 years
Traffic: 450 PCU
Subgrade CBR value: 5%
California Bearing Ratio (CBR) of WMM base: 60%
Thickness of WMM base: 100 mm
Thickness of M10 grade concrete base: 150 mm
Thickness of Tremix concrete layer: 200 mm
Grade of concrete for Tremix layer: M30
Calculation of total traffic load:
Total traffic load = Design life x Traffic = 15 x 450 = 6,750 MSA (Million Standard Axles)
Calculation of axle load:
Assuming an average axle load of 10 tons, the number of axles per day can be calculated as:
Number of axles = (Traffic in PCU) / (Number of PCU per day)
= (450 x 1000) / 3000
= 150 axles per day
Calculation of design traffic:
Design traffic = Total traffic load / (Number of days in a year x Number of hours in a day)
= 6,750 x 10^6 / (365 x 24)
= 768 MSA
Calculation of CBR strength requirement for WMM base:
CBR strength requirement for WMM base = (Design traffic / 10^6) x (WMM thickness / 1000)
= (768 x 10^6 / 10^6) x (100 / 1000)
= 76.8
The CBR strength of the WMM base is 60% and as it is greater than the required strength, it is safe for use.
Calculation of thickness of M10 grade concrete base:
Thickness of M10 grade concrete base = (Design traffic / (CBR of subgrade x 8.2))^(1/3)
= (768 x 10^6 / (5 x 8.2))^(1/3)
= 225 mm
As the provided thickness of M10 grade concrete base is 150 mm, it is safe for use.
Calculation of thickness of Tremix concrete layer:
Thickness of Tremix concrete layer = (Design traffic / (CBR of subgrade x 6))^(1/3)
= (768 x 10^6 / (5 x 6))^(1/3)
= 191 mm
As the provided thickness of Tremix concrete layer is 200 mm, it is safe for use.
Reinforcement Calculation:
Diameter of the reinforcement bar = 12 mm
Spacing of the reinforcement bars = 200 mm
Area of steel per meter width of the road = (Ï€/4) x 0.012 x 0.012
= 0.0001131 sq.m
Area of reinforcement required per meter width of the road = (Asf x σst)/0.9
Asf = (K1 x K2 x K3 x K4 x (fcu x b x D))/(σst x (D-0.4)) where
K1 = 0.87 (for grade M30 concrete and 12 mm diameter bars)
K2 = 1.0 (for spacing of 200 mm)
K3 = 1.0 (for mild exposure condition)
K4 = 1.3 (for fatigue resistance)
fcu = 30 N/mm^2 (compressive strength of M30 grade concrete)
b = 1000 mm (width of the road)
D = 200 mm (thickness of the concrete pavement)
σst = 140 N/mm^2 (allowable stress for HYSD bars)
Asf = (K1 x K2 x K3 x K4 x (fcu x b x D))/(σst x (D-0.4))
Asf = (0.87 x 1.0 x 1.0 x 1.3 x (30 x 1000 x 200))/(140 x (200-0.4))
Asf = 425.14 mm^2
Area of steel per meter width of the road = (Ï€/4) x 12 x 12
Area of steel per meter width of the road =113.0973 sq.mM
Number of bars required per meter width of the road = (Asf/Area of steel per meter width of the road)
Number of bars required per meter width of the road = (425.14/113.0973)
Number of bars required per meter width of the road = 3.76098
Therefore, 3.761 say, 4 numbers of 12mm diameter bars are required per meter width of the road for the reinforcement of Tremix concrete pavement.
Abstract
| Sr No. | Quantity | Unit | Description of Item | Rate | Amount in Rupees |
|---|---|---|---|---|---|
| 1.1 | 761.25 | Cubic Metre | Excavation for roadway in earth, soil of all sorts, sand, gravel or soft murum including dressing section to the required grade, camber and side slopes and conveying the excavated materials with all lifts upto a lead of 50m. and spreading for embankment or stacking as directed. (Item No. 2.11) | 130.9 | 99647.63 |
| 1.2 | 187.5 | Cubic Metre | Wet Mix Macadam -- Providing, laying, spreading and compacting graded stone aggregate to wet mix macadam specification including premixing the Material with water at OMC in mechanical mix plant carriage of mixed Material by tipper to site, laying in uniform layers with paver in sub-base/base course on well prepared surface and compacting with vibratory roller to achieve the desired density. Laying By Grader/Paver. (Item No. 3.23) | 2824.1 | 529518.75 |
| 1.3 | 281.25 | Cubic Metre | Providing and laying Cast in situ/Ready Mix cement concrete in M-10 of trap/granite/quartzite/gneiss metal for foundation and bedding including bailing out water, Steel centering, formwork, laying/pumping, compacting, roughening them if special finish is to be provided, finishing if required and curing complete, with fully automatic micro processor based PLC with SCADA enabled reversible Drum Type mixer/concrete Batch mix plant(Pan mixer) etc. complete. With fine aggregate(Crushed sand VSI Grade) (Item No. 24.01) | 7042.15 | 1980604.69 |
| 1.4 | 1875 | Square Metre | Providing and laying 125 micron Low Density Polyethylene(LDPE) sheet confirming to IS 3395 : 1997 below concrete pavement including all materials and labour complete. (Item No. 5.19) | 33 | 61875 |
| 1.5 | 375 | Cubic Metre | Providing and laying in situ cement concrete M-30 with tremix treatment for 200mm thickness for Concrete Road is including laying plastic sheet for 125 micron thickness with groove cutting of 4mm wide and 20mm deep with necessary refilling with polysuphide sealent(Pouring grade) confirming to BS : 5212-1989 into sawed groove widened at top for sealent reservoir of specified size and shape as per detailed drawing including fixing Polyethylene foam backer rod of required diameter(excluding reinforcement) with coarsen and fine aggregate Using V.S.I.Quality Artifitial Sand etc. complete with fully automatic micro processor based PLC with SCADA enabled reversible Drum Type mixer/concrete Batch mix plant(Pan mixer) etc. complete. (Item No. 5.22b) | 10136.2 | 3801075 |
| 1.6 | 52.988 | Metric Tonne | Providing, cutting, bending, hooking, tying and laying in position TMT FE 500 steel bars for reinforcement for all RCC works as per detailed drawings etc. complete. (Item No. 14.01) | 97458 | 5164104.5 |
| Total Amount | 11636825.57 |
Measurements
| Sr No. | Item No. | Category | Description of Item | Unit | ||||
|---|---|---|---|---|---|---|---|---|
| 1.1 | 2.11 | Road Sub grade | Excavation for roadway in earth, soil of all sorts, sand, gravel or soft murum including dressing section to the required grade, camber and side slopes and conveying the excavated materials with all lifts upto a lead of 50m. and spreading for embankment or stacking as directed. | Cubic Metre | ||||
| Description of Measurement | No. | Length | Width | Height | Quantity | Unit | ||
| To avoid Excavation and to Improve Subgrade strength | 1 | 500 | 3.75+0.6 | 0.35 | 761.25 | Cu.M. | ||
| Net Quantity | 761.25 | Cu.M. | ||||||
| 1.2 | 3.23 | Road Sub Base and Base Course | Wet Mix Macadam -- Providing, laying, spreading and compacting graded stone aggregate to wet mix macadam specification including premixing the Material with water at OMC in mechanical mix plant carriage of mixed Material by tipper to site, laying in uniform layers with paver in sub-base/base course on well prepared surface and compacting with vibratory roller to achieve the desired density. Laying By Grader/Paver. | Cubic Metre | ||||
| 1 | 500 | 3.75 | 0.1 | 187.5 | Cu.M. | |||
| Net Quantity | 187.5 | Cu.M. | ||||||
| 1.3 | 24.01 | Plain Cement Concrete | Providing and laying Cast in situ/Ready Mix cement concrete in M-10 of trap/granite/quartzite/gneiss metal for foundation and bedding including bailing out water, Steel centering, formwork, laying/pumping, compacting, roughening them if special finish is to be provided, finishing if required and curing complete, with fully automatic micro processor based PLC with SCADA enabled reversible Drum Type mixer/concrete Batch mix plant(Pan mixer) etc. complete. With fine aggregate(Crushed sand VSI Grade) | Cubic Metre | ||||
| 500 | 3.75 | 0.15 | 281.25 | Cu.M. | ||||
| Net Quantity | 281.25 | Cu.M. | ||||||
| 1.4 | 5.19 | Rigid Pavement | Providing and laying 125 micron Low Density Polyethylene(LDPE) sheet confirming to IS 3395 : 1997 below concrete pavement including all materials and labour complete. | Square Metre | ||||
| 500 | 3.75 | 1875 | Sq.M. | |||||
| Net Quantity | 1875 | Sq.M. | ||||||
| 1.5 | 5.22b | Rigid Pavement | Providing and laying in situ cement concrete M-30 with tremix treatment for 200mm thickness for Concrete Road is including laying plastic sheet for 125 micron thickness with groove cutting of 4mm wide and 20mm deep with necessary refilling with polysuphide sealent(Pouring grade) confirming to BS : 5212-1989 into sawed groove widened at top for sealent reservoir of specified size and shape as per detailed drawing including fixing Polyethylene foam backer rod of required diameter(excluding reinforcement) with coarsen and fine aggregate Using V.S.I.Quality Artifitial Sand etc. complete with fully automatic micro processor based PLC with SCADA enabled reversible Drum Type mixer/concrete Batch mix plant(Pan mixer) etc. complete. | Cubic Metre | ||||
| 1 | 500 | 3.75 | 0.2 | 375 | Cu.M. | |||
| Net Quantity | 375 | Cu.M. | ||||||
| 1.6 | 14.01 | Bridge Super Structure | Providing, cutting, bending, hooking, tying and laying in position TMT FE 500 steel bars for reinforcement for all RCC works as per detailed drawings etc. complete. | Metric Tonne | ||||
| (500.00/4)/1000 | 3.75 | 0.785 | 12x12 | 52.988 | MT | |||
| Net Quantity | 52.988 | MT |
Here's a comparative chart for the design of Tremix concrete roads versus pavement quality concrete roads:
| Parameter | Tremix Concrete Road Design | Pavement Quality Concrete Road Design |
|---|---|---|
| Subgrade preparation | The subgrade should be compacted to the desired density and a layer of granular material (sub-base) should be placed on top. The sub-base layer should be at least 100 mm thick. | The subgrade should be compacted to the desired density and a layer of granular material (sub-base) should be placed on top. The sub-base layer should be at least 150 mm thick. |
| Concrete mix design | The concrete mix should have a compressive strength of at least 30 MPa and a maximum aggregate size of 20 mm. | The concrete mix should have a compressive strength of at least 35 MPa and a maximum aggregate size of 20 mm. |
| Reinforcement | As per design requirement | As per Indian standards, In CRPC minimum 0.15% steel reinforcement is required. The reinforcement should be placed in the bottom third of the slab. |
| Thickness | 150-200 mm. | 200-250 mm. |
| Joint spacing | Generally 4-6 m. As per Indian standards, maximum joint spacing should be 5 m. | Joint spacing can be wider or narrower depending on traffic and climate conditions. As per Indian standards, maximum joint spacing should be 5 m. |
| Joint type | Dowel bars are typically used. | Tie bars or dowel bars can be used. |
| Curing | Wet curing is required for at least 7 days. As per Indian standards, curing should be done for a minimum of 14 days. | Curing can be done with wet burlap or curing compound. As per Indian standards, curing should be done for a minimum of 7 days. |
| Surface finish | Smooth and uniform. | Texture can be varied for skid resistance and aesthetics. |
| Construction method | Tremix machine is used for laying and leveling the concrete. | Pavers or slipform machines are used for laying and finishing the concrete. |
| Cost | Generally lower than pavement quality concrete roads. | Generally higher than Tremix concrete roads. |
It's important to note that the selection of the road design depends on various factors such as traffic volume, climate conditions, soil conditions, and budget. Both Tremix concrete roads and pavement quality concrete roads have their own advantages and disadvantages, and the choice should be made based on a thorough analysis of the project requirements.
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