Cement Energy and Environment

• ' • Fibers Locally available steel fibers are used with aspect ratio of 50. Diameter of fibers used is 1mm. Superplasticizer The super plasticizer used in this experimental work is SP430 (Conplast). It is manufactured by FOSROC. Water Potable water is used in the mix of concrete and also for the curing of samples. Mix Design For M25 Basic Concrete Final mix proportions are C:FA:CA 1:1 .67:2.85 Water cement ratio=0.45 (45%), Steel fibres with an aspect ratio 50. Quantities required for one cubic meter of concrete are: Cement=413 Kgs ., Pumice stone=115 kgs., Fine aggregates=690 kgs. , Coarse aggregates=11 78 kgs., Water cement ratio=0.45. Mix Combinations From the basic M25 concrete mix, OPC was replaced by fly ash at 0 and 20 percent (optimum) and by CSF at 0 and 10 percentages. Conventional crushed granite stone aggregate was replaced by, pumice aggregate by 0, 25, 50, 75 and 100 percentages. Steel fibres were employed at volume percentages of 0, 0.5 and 1.0. In all, 30 combinations of concrete mixes including the base mix were prepared and tested . The details of the mixes are given in table 1. Mixing, Casting, Curing and Testing All the ingredients of all the combinations were mixed in a pan mixer. Required number of standard cube, cylinder and beam specimens were cast and cured for 28 days. Tests for workability on fresh concrete, compressive, split tensile and flexure tests on hardened samples were conducted. Flexural deflections were measured during flexural strength tests. Standard procedures for various operations were followed. Test Results Test results of weights of various specimens taken before testing are given in table. 2 for various combinations. The 28 day compressive and tensile strength results are presented in table.3. The variation of unit weight of various light weight concrete combination is plotted and shown in fig.1 , fig.2 and fig.3 give the variation of flexural strength for various percentages of light weight aggregates for 0.0 and 1.0 fiber per percentages. Typical load (vs) deflection characteristics are plotted for 50 percent pumice for 0.5 and 1.0 percentages of steel fibers in fig.4. Discussion of the Results The results are discussed as follows Workability of Fibrous Triple Blended Light Weight Concrete Mixes While using the porous light weight aggregate like pumice, due to absorption of water by the aggregate, some correction is required in w/c ratio to maintain the workability level. When steel fibres are also added, workability is further affected. Hence use of super plasticizer is necessary for fibrous light weight aggregate (pumice) concrete. 3 ~---------------------------- §! 2-:r:=~=~~;;::~~= ! 1.5 1---------------- --o,o.o tl -4-0,20,10 0.5 1---------------------------- 0 ~-------------------------- 0 20 40 60 so 100 120 % of light weight aggregate F1g.l . variation of concrete we1ght With percentage of light weight aggre– gatel1% fibrel 4.5 4 --- ~ 3.5 ........ --.... -...._ .t: 3 "--.. ""' _. ~ 2.5 ~- -+- 0,0,0 2 ii) ---0.20,10 1 1.5 1 0.5 0 0 20 40 eo ao 100 120 % of light weight aggregate F1g 2 Vanation of flf!)llUral strength With percentage of light weight aggre– gate!O% librel 49