Cement, Energy and Environment

higher when compared to the results using river sand as fine aggregate. Flexure strength of concrete was determined using prisms (size: 100 x 100 x 500 mm) as per IS 516 code guidelines. Three specimens were tested in each category and the mean values are reported in Table 2. The results show that use of Manufactured Sand as fine aggregate exhibits 12 – 15% higher flexure strength in comparison to the results of concrete with river sand. 4 Concrete Grade Water- Cement ra o River Sand Manufactured Sand Slump (mm) Compressive Strength (MPa) Flexural Strength (MPa) Slump (mm) Compressive Strength (MPa) Flexural Strength (MPa) M30 0.50 80 42.20 3.90 55 44.78 4.54 M20 0.50 110 37.68 3.29 76 41.03 3.86 Table 2: Characteris cs of concrete using Manufactured Sand and River sand Bond strength The bond between rebar and the concrete was examined by conduc ng pull out test. The pull out test was performed using 12 mm HYSD bar for M20 concrete as per IS 2770 code guidelines. The bond strength at failure (mean of 3 specimens) with river sand and Manufactured Sand as fine aggregates is 13.9MPa and 14.1MPa respec vely. The bond strength is found to be marginally higher in case of concrete with Manufactured Sand. The stress-strain behaviour of M- sand and river sand concretes were found to be similar. Cement Mortar The details of the tests on Mortar, comparison of results tabulated in Table 3 and inferences drawn are given below. Flow/workability Workability of the mortar should be such that it allows the mason to spread the mortar easily and mortar adheres well to the masonry units. It is affected by mortar composi on as well as water-cement ra o. Workability of the fresh mortar can be measured by conduc ng a flow table test as per code guidelines (BS – 4551). Workability of fresh mortar is expressed as flow value. Flow tests were performed on the two types of mortars in order to establish rela onships between flow and water-cement ra o. The graphs given below show the flow versus water-cement ra o rela onships for the 1:6 and 1:4 cement mortars respec vely. Mortars with Manufactured Sand exhibited be er flow characteris cs. The ideal flow values as collected from different construc on sites by IISc are in the range of 85 to 100%. To achieve a given flow value, mortar with Manufactured Sand characteris cs for the mortars in hardened state 1:6 Mfd. Sand mortar at 85%flow