PERFORMANCE EVALUATION OF PCC PAVEMENTS USING CALCIUM CHLORIDE AS ADMIXTURE

Abstract

Cement concrete roads are known for their long life, lesser maintenance and smooth riding. Almost all the developed countries and many developing countries have been impressed with their superior performance and are continuing with their construction on a large scale. As flexural strength of cement concrete is a major strength parameter responsible for the strength and consequently the performance of concrete pavements, a need was felt that the design of concrete mix be done for roads on the basis of flexural strength and not compressive strength which is the usual judging parameter. Also, in the modern times when the economy of the countries is so much dependent upon transportation facilities including roads which can carry uninterrupted traffic, normal 28 days curing period need to be reduced. This reduction in the curing period is possible by the use of admixtures which can give an early strength. Under the present investigation, an attempt has been made to evolve a tentative procedure for the design of concrete mix on the basis of flexural strength by developing a correlation between compressive strengl.hh and flexural strength at 7 days curing period. Also, the performance evaluation of concrete pavement slab with and without CaCl2 (calcium chloride) as an admixture at 1 clay curing has been done. The material properties evaluated are (Xi) mainly compressive strength and flexural strength. The pavement slabs of size lrnxirnxu.im were cast without CaC12 and with 1%. CaC12. The study reveals that the flexural strength is increased by 2-13% with 1% CaCl2 and 5.4- 17.54% with 1.2% CaC12. The increase in compressive = .eng h -._- respectively 15-28% and 17-•33X. Testing of pavement sahs showed that the load carrying capacity' of the concrete slab is appreci able wi th the dii.ion of CaC12' at early age i . e.. 7 day curing The lah:ors.tory sti:.dy show-=— that the FCC pavement slab with 1% CaC1.2 due to their better ; erformance can be advantageously used. However, the C]e;ura1 strength ever. 'Alth the addition of 1% CaC12 with 7 day cur-in; is less than the minimum specified as !l N/mm2. The properties of concrete oavrment be Improved upon by. the addition of high early strength cement, admixtures or by adopting low workability so that the minimum specified value of flexural strength be achieved in early ages and traffic can be allowed as soon as possible. r