Fractal Experimental Study On Concrete Aaggregate Gradation And Surface Cracks Expansion

Concrete is a two-phase composite materials which is composed of hardened cement paste and aggregate.The aggregate volume is about 60% to 70% of the concrete volume, so the mechanical properties of aggregate, shape and appearance and so on influence concrete strength and the expansion of the concrete surface crack. Aggregate grading play a significant role in the mechanical properties of concrete.This article devotes in using the fractal dimension ofbiaozheng the fractal theory to describe the aggregate grading and the surface cracking of the concrete. Using a new method to study the concrete compressive strength, anti-booklet intensity and the expansion of the surface cracks. The main research work and conclusions of the paper are as follows:(1)Under the condition of the same water-cement ratio, mixing, curing conditions and the onlydiffierence of the the aggregate gradation fractal dimension, compounding crushed stone and pumice two kinds of concretes, testing the concretes compressive strength and anti-booklet intensity.(2)Contrasting and analyzing the changes of the compressive strength and anti-booklet intensity of the same aggregate concretes briquette with the changes of the aggregate gradation fractal dimension. The conclusions are as follows:The concretes intensity increase with the fractal dimension reduces gradually, the intensity is the biggest when the fractal dimension reach the most superior aggregate gradation fractal dimension, thereafter the intensity drops with the reduction of the fractal dimension.(3)Comparing the crushed stone thick aggregate concretes intensity with the pumice thick aggregate concretes intensity under the same fractal dimension condition ,obtaining the crushed stone concrete intensity is bigger than the pumice stone concrete intensity when the aggregate gradation fractal dimension is the same.(4)Photographying the briquette surface cracks of increasing the same length load with the digital camera when testing compressive strength.Compiling the matlab procedure to obtaining the box-counting dimension of the concretes briquette surface cracks and the changes of the fractal dimension of the concretes surface cracks expansion.(5)Qualitative analyzing the relations of the aggregate gradation fractal dimension and the changs of the concrete surface cracks fractal dimension.