Development Of Castor-straw Concrete Block

At present,our country's soil is heavily polluted by heavy metals.Castor has good ability to absorb heavy metals.It is also an economic crop and is suitable for planting in areas contaminated by heavy metals.However,castor stalks that have absorbed heavy metals cannot be directly returned to the field or burned,otherwise it will cause new pollution.Therefore,the best treatment method is to make these straws into building materials for solidification and reuse.First of all,based on the production technology of ceramsite concrete blocks,the production technology of castor straw concrete blocks is proposed in this paper through research and experiments.Concrete blocks with different castor straw content were trial-produced to prepare for subsequent experiments and research.Secondly,in accordance with the relevant standards,the compressive strength test of the blocks was carried out.The influence of castor straw content on the mechanical properties of the blocks was analyzed.And the mechanical properties of the castor straw block and ceramsite concrete blocks were compared.The maximum content of castor is obtained when the compressive strength index is met under different usage conditions.Third,based on the thermal performance test data,the influence of castor straw content on the heat transfer coefficient of block is analyzed.Finally,the applicable areas of castor straw concrete blocks were analyzed.The research results show that:in the mixing process of the block production process,the castor straw concrete material is more prone to layering and segregation than the ceramsite concrete material.This affects the stability of the mechanical properties of the block,so it is necessary to extend the mixing time of the block and the vibration time.With the increase of castor straw content,the compressive strength of castor straw concrete blocks gradually decreases.So the more castor straw content,the worse the load-bearing performance of the block.When the castor straw contents of experimental samples are7%,10%,13%,16%,and 19%,respectively,the densities correspond to1276kg/m~3,1196kg/m~3,and 1119kg/m~3,1037kg/m~3,960kg/m~3,the compressive strength is 6.9MP,5.3MP,4.2MP,3.3MP,2.4MP respectively.When the castor straw content is 10%,the average compressive strength of the block is greater than 5.0 MP,the minimum compressive strength of a single block is greater than 4.0 MP,and their average density is less than 1200kg/m~3,which meets the requirements of"Lightweight Aggregate Concrete Small Hollow Blocks"(GB/T15229-2011)strength grade MU5.0.With the increase of its castor straw content,the heat transfer coefficient of the concrete block gradually decreases.The heat transfer coefficients of the same five experimental samples are 1.033W/(m~2·K),0.923 W/(m~2·K),0.801 W/(m~2·K),0.724 W/(m~2·K),0.689W/(m~2·K)respectively.When the percentage of castor straw is not less than 13%,and other materials are the same,the castor straw concrete block is better than the ceramsite concrete block(the ceramsite content is5%,and the heat transfer coefficient is 0.89 W/(m~2·K))in terms of thermal insulation effect.It is mainly because as the content of castor straw increases,the straw is more densely distributed in the concrete block,which increases the block's effect on heat transfer,and the thermal insulation effect is increased.Therefore,considering the compressive strength and heat transfer coefficient comprehensively,it is recommended that the castor straw content of the concrete block is 10%.The castor straw concrete block meeting the strength grade MU5.0 is suitable for popularization in the partition wall of urban buildings in severe cold and cold areas,and also suitable for popularization and use in the outer walls of rural residential buildings in hot summer and cold winter areas and hot summer and warm winter areas.