Flexural and Split Tensile Strength Properties of Lime Cement Concrete

This paper investigated the flexural strength and split tensile strength properties of hydrated lime cement concrete. Ordinary portland cement was partially replaced by hydrated lime at varying percentages ranging from 5% to 30%. Concrete under study was made of ordinary portland cement (OPC), hydrated lime, river sand, granite chippings and water. The test specimen were prototype concrete beams of sizes 150x150x600mm and concrete cylinders of dimensions 150x300mm. Three concrete specimens were cast for each mix ratio considered, and cured in open water tanks for 7, 14, 21, and 28 days for the beams, and cylinders respectively. Since there were 30 different mix proportions considered, a total of 360 concrete prototype beams, and 360 concrete cylinders were produced and cured before testing in tension. Maximum design strength recorded in flexure at 7, 14, 21 and 28 days were 3.08N/mm2, 3.580N/mm2, 4.910N/mm2 and 5.03N/mm2 respectively, while those recorded in splitting were 1.565N/mm2, 2.350N/mm2, 3.605N/mm2, and 3.725N/mm2respectively. It was observed that tensile strength values from the flexural test gave higher values than those of the split tensile test. Strength properties increased with curing age. Optimum replacement of OPC with hydrated at 28 days curing age was observed at 13.83% for both properties. Optimum mix ratio for the two properties studied was 0.863:0.138:2.625:5.250 at a water cement ratio of 0.58. Hydrated lime cement concrete can be used effectively for structural works at curing age of 28 days and beyond

Anticipating the Compressive Strength of Hydrated Lime Cement Concrete Using Artificial Neural Network Model

In this research work, the levernberg Marquardt back propagation neural network was adequately trained to understand the relationship between the 28th day compressive strength values of hydrated lime cement concrete and their corresponding mix ratios with respect to curing age. Data used for the study were generated experimentally. A total of a hundred and fourteen (114) training data set were presented to the network. Eighty (80) of these were used for training the network, seventeen (17) were used for validation, and another seventeen (17) were used for testing the network's performance. Six (6) data set were left out and later used to test the adequacy of the network predictions. The outcome of results of the created network was close to that of the experimental efforts. The lowest and highest correlation coefficient recorded for all data samples used for developing the network were 0.901 and 0.984 for the test and training samples respectively. These values were close to 1. T-value obtained from the adequacy test carried out between experimental and model generated data was 1.437. This is less than 2.064, which is the T values from statistical table at 95% confidence limit. These results proved that the network made reliable predictions. Maximum compressive strength achieved from experimental works was 30.83N/mm2 at a water-cement ratio of 0.562 and a percentage replacement of ordinary portland cement with hydrated lime of 18.75%. Generally, for hydrated lime to be used in making structural concrete, ordinary portland cement percentage replacement with hydrated lime must not be up to 30%. With the use of the developed artificial neural network model, mix design procedure for hydrated lime cement concrete can be carried out with lesser time and energy requirements, when compared to the traditional method. This is because, the need to prepare trial mixes that will be cured, and tested in the laboratory, will no longer be required