Delayed Analysis of Superplasticized Fresh Concrete

W Perera, K Kathriarachchi, E Peiris
International Research Journal of Engineering and Technology   unpublished
Fresh analysis techniques for concrete mix can be used to check the compliance of mix proportions with specified requirements. Due to the practical difficulties related with conventional analysis techniques, the cement contents are rarely checked. Thus Rapid Analysis Machine can be used to analyze the cement content of fresh concrete. Rapid Analysis Machine is quick and considered reliable if concrete is tested within an hour of being mixed. Fresh concrete can be kept without setting for at
more » ... setting for at least 7 days by using sugar for the determination of cement content using Rapid Analysis Machine. This technique is useful in finding the cement content of concrete mixes supplied to construction sites, which do not have ready access to a suitable fresh concrete analysis facility. The concrete containing superplasticizers can be tested using this method. Testing was done for three superplasticizer dosages which were 0ml, 800ml and 1000ml per 100kg of cement content, respectively. The sugar percentage added to a single sample was 2% by the mass of cement content of the sample. The test were conducted for the samples with given sugar and superplasticizer dosages after three delay times, 1 hour, 24 hour and 7 days. Five samples of each sugar and superplasticizer combination were checked using Rapid Analysis Machine. The average cement content of the five samples was taken as the cement content given by Rapid Analysis Machine for a particular test. The test results reveal that the cement content can be determined to a variation of 3.5% from actual cement content, within 7 days of initial adding of mixing, even if the fresh concrete contains superplasticizers.