Research On Lime-fly Ash Stabilized Weathered Sand As A Base

The two ash gravel semi-rigid base is widely used in all kinds of highways in China because of its high carrying capacity,convenient material and simple construction.But in the process of mining and processing,gravel is prone to damage and harm natural environment and human production and living environment.Sustainable development is the basic national policy of our country.In highway engineering construction,we should take full account of local materials and select materials and programs that are conducive to environmental protection.Yichang is a hilly area,widely distributed with a large number of weathered sand,at the same time,the weathered sand has the advantages of low price and low transportation cost.In Yichang highway construction,scientific and rational use of weathered sand can reduce the cost of the project and bring great social and economic benefits to the local area.In the past,weathered sand is usually used in the subgrade material.In this paper,the weathered sand is used as the research object.In the light of the full use of local resources,the purpose of alleviating the relative lack of stone material and the higher transportation distance and higher cost is to be used to replace the gravel as the base material for the road.The effects of lime content,two ash ratio,different curing ages and dry wet cycles on the mechanical properties of two ash stabilized weathered sand base materials were studied.The main mechanical indexes of the two ash stabilized weathered sand are unconfined compressive strength,splitting strength and resilient modulus.According to the test regulations for the stable material of inorganic binder,according to the maximum dry density and the best water content,4%,5%,6%,7%,8% lime and two ash ratio of 1:2,1:3 and 1:4 are made to make two ash stabilized weathered sand without side limit compression test pieces,splitting strength test pieces and modulus of modulus of resilience under standard conditions.For 7 days,14 days,21 days and 28 days,the corresponding tests were carried out to study the influence rules of two ash content and proportion and curing age on the mechanical indexes of two stabilized weathered sand.In addition,the change law of mechanical indexes of two grey stabilized weathered sand after the 1～7 dry and wet cycle for 28 days of curing age was studied for the future road basis.It provides a reference for the design and construction of the layer.The main conclusions of this paper are as follows:1)the unconfined compressive strength of lime and two ash stabilized weathered sand formed by the lime and two ash ratio of 4%,5%,6%,7% and 8% with 1:2,1:3 and 1:4 fly ash are all satisfied as the strength index of heavy traffic at the primary level of the first grade highway.2)the strength of two gray stabilized weathered sand with each two ash content and three kinds of proportions increased with the increase of curing age,and the growth rate of early strength was faster and the growth rate of later strength slowed down.When the lime content is 8%,the strength of the two ash ratio is 1:3,and the strength is two,and the ash ratio is 1:4.3)when the curing age is 7d,with the increase of lime content,the strength of two ash stabilized weathered sand with two ash ratio is 1:2 and 1:3,but the strength of two ash ratio for 1:4 increases first and then decreases.After the curing age is increased from 7d to 28 d,the strength of two ash stabilized weathered sand with three two ash ratio increases with the increase of lime content.4)In this paper,the best mixture ratio of two ash stabilized weathered sand is 8:24,which can be used as a reference value in the construction of basic units in highway engineering.